# Sticky  Tire pressure for all around XC riding?



## Lugi (Jul 10, 2009)

I was curious to know what tire pressure is the best for all around xc use?
I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
Any suggestions would be great. Thanks


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## Spawne32 (May 22, 2009)

i run 40psi on 2.00 tires on my rigid


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## Surly29 (Jun 8, 2009)

As low as possible. I'd start at the lowest recommended pressure (as printed on the tire) and see if you get a pinch flat (small holes on both sides of tube where it contacts the rim). If so, put in a few more psi and run that. If you don't get a pinch flat, run a few psi lower until you do pinch flat.

Tire pressure is an individual thing. You may also play with the pressure to see how it effects handling, traction, and rolling-resistence.


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## AZ (Apr 14, 2009)

How much do you weigh? A 140 lb. rider can get away with much lower psi than a 210 lb. rider .


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## shiggy (Dec 19, 1998)

Lugi said:


> I was curious to know what tire pressure is the best for all around xc use?
> I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
> I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
> Any suggestions would be great. Thanks


You have to experiment. Keep dropping the pressure until you start getting pinch flats or the tires feel squirmy in the corners, then add 2-3 psi. This will be where most tires will preform the best, though a few models may have a sweet spot that is a little higher depending on riding style and terrain.


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## trailville (Jul 24, 2006)

I'm a big fan of lower pressures. I generally run about 22-23 on my 2.3-2.4 tires, 24-25 on 2.1's. I weigh 160 and ride rocky and rooty trails, but the rocks around here tend to not have sharp edges. I will add a couple psi if I expect to be riding somewhere with sharper rocks. My trails also tend to be a lot of slow technical riding, so the low pressure really pays off. If I expect to ride somewhere with higher speed turns, I will up the pressure a little to avoid that squirmy feeling Shiggy mentioned (it can be real unnerving). I am running tubes (not tubeless). 

Also be aware that I have yet to find 2 tire pressure gauges that give the same reading, so my psi listings are relative to my main tire gauge.


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## Spawne32 (May 22, 2009)

trailville said:


> I'm a big fan of lower pressures. I generally run about 22-23 on my 2.3-2.4 tires, 24-25 on 2.1's. I weigh 160 and ride rocky and rooty trails, but the rocks around here tend to not have sharp edges. I will add a couple psi if I expect to be riding somewhere with sharper rocks. My trails also tend to be a lot of slow technical riding, so the low pressure really pays off. If I expect to ride somewhere with higher speed turns, I will up the pressure a little to avoid that squirmy feeling Shiggy mentioned (it can be real unnerving). I am running tubes (not tubeless).
> 
> Also be aware that I have yet to find 2 tire pressure gauges that give the same reading, so my psi listings are relative to my main tire gauge.


22psi? isnt that kinda low? whats your tire look like while riding.


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## shiggy (Dec 19, 1998)

Spawne32 said:


> 22psi? isnt that kinda low? whats your tire look like while riding.


Evidently, not for him. I rarely have more than 30psi (usually less) in any of my tires and I outweigh trailville by at least 20 pounds.

I do not look at my tires while riding.


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## Spawne32 (May 22, 2009)

shiggy said:


> Evidently, not for him. I rarely have more than 30psi (usually less) in any of my tires and I outweigh trailville by at least 20 pounds.
> 
> I do not look at my tires while riding.


i mean like when weight is on it, i would figure 20psi on that size tire would be almost flat


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## Fiendbear (May 8, 2009)

Drop psi until you get pinch flats. Every one and every ride is different. If you ride slow and/or easy, you can get away with very low pressures. However, I'm only 140lbs, but can't drop the rear below 35 psi or I will pinch flat when pounding over rough trails.


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## mr.niles (Feb 5, 2007)

i am always somewhat confused about what pressures to run for trail riding, but what seems to "feel" best to me (i weight about 170lbs with gear) is 28 psi front, and 36 psi rear on maxxis high roller 2.35 single ply's, give or take a very few psi. any more on the front and it feels sketchy, less and i feel the rim getting tagged on bigger rocks. on the rear, less than 36 and it feels like the bike won't roll fast enough (and rim gets tagged), more and i can feel the back skipping over too much stuff, braking is bad, and too much boot-boot. i tend to try to run as much pressure as i can get away with though, because i have more fun riding when the bike rolls faster - this is for general trail riding. but for bike parks i run 2.5 maxxis 2-ply dh tires with 27 psi front, and 35 rear, exactly. for dirt jumps i run 40 psi front, and 50 psi rear for railing berms at high g's - although this can vary more since you don't have to deal with terrain on flow trails.

why more in back than front? because i DO look at my tires while i ride! one of the things i do when testing a different tire pressure is do a "tire sag" check - i sit on the bike and look at the tire to see how much it bulges at a certain psi. i can't explain here how to judge this, but keep in mind that a tire works best on a certain size of contact patch that will vary with psi, tread design, rider weight, casing design, tire size, rider weight distribution, riding style, dynamic forces while riding, and other factors. as part of my riding style, i try to keep the front end light as often as i can by keeping my weight on the pedals (not on my hands), and when riding faster and more aggressive (which i do as often as possible) the weight distribution shifts more rearward. add to this that the weight distribution on my bike is already 40/60 front-to-rear. so, the weight distribution calls for more pressure in the rear and less in the front to keep things balanced-out.


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## Le Duke (Mar 23, 2009)

I'm 143lbs, riding 24f/28r on 26x2.0" at the moment.

The rear is a bit skinny for a 2.0; when I get a true 2.0, I'll drop the pressure to 26ish.


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## shiggy (Dec 19, 1998)

mr.niles said:


> i am always somewhat confused about what pressures to run for trail riding, but what seems to "feel" best to me (i weight about 170lbs with gear) is 28 psi front, and 36 psi rear on maxxis high roller 2.35 single ply's, give or take a very few psi. any more on the front and it feels sketchy, less and i feel the rim getting tagged on bigger rocks. on the rear, less than 36 and it feels like the bike won't roll fast enough (and rim gets tagged), more and i can feel the back skipping over too much stuff, braking is bad, and too much boot-boot. i tend to try to run as much pressure as i can get away with though, because i have more fun riding when the bike rolls faster - this is for general trail riding. but for bike parks i run 2.5 maxxis 2-ply dh tires with 27 psi front, and 35 rear, exactly. for dirt jumps i run 40 psi front, and 50 psi rear for railing berms at high g's.


Some time you should actually put a clock (or GPS) on your runs and see how different pressures affect your speeds.

I have done this with a Garmin Edge GPS when testing tires. The runs that felt the fastest were many times the slowest. They where exciting and it seemed I was going into the corners at a higher speed but in reality the tires where just bouncing and sliding more and harder to control. Slower into the turn and slower yet coming out of them. Heck, the higher pressure runs where even slower on the climbs.

That is not to say the faster, low pressure runs were more fun. There was a lot less drama in covering the lap. Definitely not as thrilling a ride.


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## shiggy (Dec 19, 1998)

Spawne32 said:


> i mean like when weight is on it, i would figure 20psi on that size tire would be almost flat


The point is if you are not bottoming out the tire, it does not matter. 22psi in 2.3-2.4" tires is not unusual or "look" low (if you could see it).


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## Spawne32 (May 22, 2009)

well im about 165 pounds and 40 psi in the rear is usually where i feel comfortable, adding a bit more flex to the front tire might make it a little easier on my arms but i dont know how much more difficult it would be to accel the bike forward with lower tire pressure. I might play around with it a little more now that i got my CST copperheads mounted today.


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## mr.niles (Feb 5, 2007)

shiggy said:


> Some time you should actually put a clock (or GPS) on your runs and see how different pressures affect your speeds.
> 
> I have done this with a Garmin Edge GPS when testing tires. The runs that felt the fastest were many times the slowest. They where exciting and it seemed I was going into the corners at a higher speed but in reality the tires where just bouncing and sliding more and harder to control. Slower into the turn and slower yet coming out of them. Heck, the higher pressure runs where even slower on the climbs.
> 
> That is not to say the faster, low pressure runs were more fun. There was a lot less drama in covering the lap. Definitely not as thrilling a ride.


in fact i do have timing device coming in the mail! yeah, it's hard to tell! that's why it's confusing to me. i'm always changing my presuures around to try and figure out what is best. i will try lower pressures, but i'm just not sure where to start. any ideas?


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## HSMITH (Aug 11, 2009)

Over 190 with water and gear, 30 in the front and 32 in the rear with small 2.4's. These tires are definitively faster at 30-32 than they are at 40 or more whether I am on the road or the trail. I wouldn't have believed it if I had been told beforehand. I tried 28 in the front and 30 in the rear but felt the rim hit on both ends during that ride.


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## trailville (Jul 24, 2006)

Spawne32 said:


> 22psi? isnt that kinda low? whats your tire look like while riding.


It's fine. Remember, that pressure is in a wider 2.3-2.4 tire. Once you feel how your tires can conform to rocks and roots rather than bouncing off of them, you will appreciate lower pressures. To be honest, I've never had issues with pinch flatting. I think part of it is due to the the mainly rounded rocks we have around here (thanks glaciers), and part is due to the fact that I started mtn biking on rigid bikes and even though I run suspension now (front and full), I still unweight the bike as I go over and through stuff.

I've played with all kinds of pressures over the years. In the early 90s I started running between 30 and 35 psi because I was new to MTB and the people that knew what they were talking about recommended lower pressures (that seemed low to me at the time). Later on I got sucked into the "higher pressure is faster" thinking and started running 40 - 45. I also remember that some tires during the mid 90s started coming with separate pressure recommendations if you were riding suspension versus rigid (min pressure on suspension was like 5 or 10 psi higher), so since I was running front suspension then (if you can call a 63mm Judy suspension), I went with the recommendations.

Eventually (years later) I got sick of bouncing and glancing sideways off of every rock and root on the trail and started lowering my pressures again. Then in more recent years I discovered wider 2.3 - 2.4 XC tires (I had been running 1.95s to 2.1s up to that point) and even lower pressures, and a whole new world opened up to me. I was more than happy to trade some speed for better traction and control, but then I started reading in these forums that I probably wasn't sacrificing speed by running lower pressures anyway. So all is good:thumbsup: . Now I just feel like an idiot for running 40-45psi for all those years.


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## Squash (Jul 20, 2003)

mr.niles said:


> in fact i do have timing device coming in the mail! yeah, it's hard to tell! that's why it's confusing to me. i'm always changing my presuures around to try and figure out what is best. i will try lower pressures, but i'm just not sure where to start. any ideas?


The reason that most mtb tires are faster on dirt at lower pressures is really rather simple. A tire at lower pressure will flow or comform to bumps, smaller rocks, or square edged obsticals. A tire at higher psi doesn't do this, rather it has to make contact with the obstical and climb over it. This creates a bump that you can feel and in many cases the tire looses contact with the trail surface. It takes more time for the tire to bump over the obstical than it does to have it flow over it. The effects of higher pressure are, slower speed, less traction, less control. The lower pressure tire will have the opposite effect. But as the others have noted there is a limit to how low you can go. Rider weight, riding style, tire volume, tire construction, terrain, etc. all work to determine the "sweet spot" for a given tire. The sweet spot is that golden compormise pressure where the tire provides the best traction and performance without feeling squirmy or being so soft that you ding rims, etc. And I've never had two different tires that had the same sweet spot, and it takes a bit of work to find it. But if you go at it right it can be allot of fun.

As for where to start, Surly29 had it right. Start with the lowest recommended pressure for the tire and ride it. If you don't get a pinch and the tire doesn't feel squirmy on the first run, drop pressure on the next run by 2 or 3 psi. If you do get a pinch or tire squirm up it by 2 or 3. So drag your pump and your bike to the trail and have fun. :thumbsup: Oh and just as a side note, make sure you take a couple of spare tubes and have an inflation device along on the bike. Cause you will most likely pinch flat at least once. 

Good Dirt


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## LyNx (Oct 26, 2004)

Spanw, believe Shiggy and all the others, they know what they're talking about with lower pressures. At your weight you should easily be able to ride anywhere from about 24PSI up to prob 35PSI for trails. It may not seem right, right now, but trust me  When I first started I kept about 40 PSI in my tyres because it prevented pinch flats and helped them roll easier on the road. I've since come to realise that I needed the higher pressures with the tyre/rim combo I was using and my regular trail pressures now are between 24-30 PSI and I weigh 170lbs not geared up.



Spawne32 said:


> well im about 165 pounds and 40 psi in the rear is usually where i feel comfortable, adding a bit more flex to the front tire might make it a little easier on my arms but i dont know how much more difficult it would be to accel the bike forward with lower tire pressure. I might play around with it a little more now that i got my CST copperheads mounted today.


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## shiggy (Dec 19, 1998)

trailville said:


> It's fine. Remember, that pressure is in a wider 2.3-2.4 tire. Once you feel how your tires can conform to rocks and roots rather than bouncing off of them, you will appreciate lower pressures. To be honest, I've never had issues with pinch flatting. I think part of it is due to the the mainly rounded rocks we have around here (thanks glaciers), and part is due to the fact that I started mtn biking on rigid bikes and even though I run suspension now (front and full), I still unweight the bike as I go over and through stuff.
> 
> I've played with all kinds of pressures over the years. In the early 90s I started running between 30 and 35 psi because I was new to MTB and the people that knew what they were talking about recommended lower pressures (that seemed low to me at the time). Later on I got sucked into the "higher pressure is faster" thinking and started running 40 - 45. I also remember that some tires during the mid 90s started coming with separate pressure recommendations if you were riding suspension versus rigid (min pressure on suspension was like 5 or 10 psi higher), so since I was running front suspension then (if you can call a 63mm Judy suspension), I went with the recommendations.
> 
> Eventually (years later) I got sick of bouncing and glancing sideways off of every rock and root on the trail and started lowering my pressures again. Then in more recent years I discovered wider 2.3 - 2.4 XC tires (I had been running 1.95s to 2.1s up to that point) and even lower pressures, and a whole new world opened up to me. I was more than happy to trade some speed for better traction and control, but then I started reading in these forums that I probably wasn't sacrificing speed by running lower pressures anyway. So all is good:thumbsup: . Now I just feel like an idiot for running 40-45psi for all those years.


Well said!


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## kmacon (Nov 15, 2006)

Very well said trailville, Shiggy, Squash and others! :thumbsup: How long will it take to beat it into people that lower PSI is better. I ride with guys that insist on running upwards of 45 PSI and if you are behind them you can see their tires bouncing all over the trail. When I mention lowering pressure mostly I get the response that they don't want to pinch flat and they brush me off . Oh well, their lose.

BTW I'm 175 and on my Trek TF69er I run 22 PSI in the front Rampage 2.35 and 24 PSI in the rear Fat Albert 2.4, all tubeless with homebrew sealant (you should see my boogers!). And yes you can't just plow through rocks, roots and into logs. MTB riding should also incorporate at least a little finesse where you learn how to weight and un-weight the bike at the appropriate times.


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## kapusta (Jan 17, 2004)

Lugi said:


> I was curious to know what tire pressure is the best for all around xc use?
> I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
> I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
> Any suggestions would be great. Thanks


This is like asking what shoe size to wear. It is _greatly _effected by tire size, the tire sidewall, your weight, and where you ride.

I would start by lowering your pressure by a few pounds each ride until you either run into pinch flats or it just feels too soft.

FWIW, I am ~185 with gear, and run ~23 psi front (2.4 Big Betty) ~30 rear (2.25 Ardent). East coast rocks and roots, but not much in the way of sharp edges.


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## mr.niles (Feb 5, 2007)

*i am curious about....*

what terrain and how you guys are riding it? shiggy, squash, trailville, lynx, kmacon, kapusta, le duke - how would you describe your riding style?

i would have to say i ride like a gravity racer whenever the chance presents itself. when i brake, i cram the bike into the ground, when i corner i cram the tires onto their edge. i weight and unweight as quickly as i can, everywhere i can. i try to hit the best lines i can, but anytime the trail points downhill i am usually pinning it, so sometimes the best line is over the obstacles. of course this is not an absolute - there are pedestrians, horses, blind corners, etc that i always yeild to. but if i have a clear view, i push my limits.

a little more remembering made me realized why i am running 36 psi in the rear tire: rim damage. long story shortened: several months ago i went out riding at one of my favorite places, riding it the way i like to ride it, and i had about 33-34 psi in my rear tire which seemed fine for the climbing and slower stuff. then i got to the fun part, and while bombing down the hill and really railing the corners something hit my rear tire so hard it bent the rim with a big "smack." i was very bummed because the rims are sun equalizer 29's and they weren't cheap. plus i had to do the whole junk task of changing a tube, not being able to pump it up enough etc, etc, not to mention losing out on finishing the bomb downhill because i had way too low pressure from not being able to pump it up enough. basically ruined the rest of my ride.

on the other hand, 28 or even a little lower seems just fine in the front.

another story: 2 weeks ago at northstar, i was having a great time riding all day with 36 psi in the rear tire (2 ply tire). then on my last run i decided to really pinnit down a somewhat rocky trail. i had a great run down, went to my car, loaded-up and went home. next morning had a flat on the rear - yep, big pinch slice. luckily i have big dh rims on that bike, so no rim dings.

there have been other such incedences, but i will not include them here. overall, i have had the best "general" luck with 36 psi rear on a 2.1-2.35 tire with a single ply casing. maybe i am missing out on the benefits of lower pressure, but maybe i need the higher pressure to keep things together?

so, does anyone think that i should still try lower pressures, or have i hit my "pinch limit" already? i will say that i HATE GETTING FLATS out on the trail, and i WILL NOT GO TUBELESS.

i REALLY want to be able to go with lower pressures, because i DO know all about the tire conforming to the irregulaties using less energy to continue forward vs non-conforming, and i have ridden with lower pressures and experienced the way the tires "float" over the ground. but.....i have experienced problems going lower than 35 psi with the tires i like to use, so............

?????????????? what next????


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## LyNx (Oct 26, 2004)

Well Mr.Niles, first up I'll say this .......... Look into buying a GOOD frame [ump so if you get a flat you can inflate your tyre(s) back to whatever PSI you so desire :skep: Seriously if the POS you currently have can't even get you tyres back to 36 PSI, just toss it in the garbage, don't even think about it :madman: The pump I carry is a Topeak Mountain Morph and can inflate ROAD tyres back to 100 PSI when the need arises.

Not sure how much skill I have or how hard I hit stuff, but so far I haven't managed to pinch flat a 29er :skep: My terrain down here in general is pretty slowish tech, with 1 or 2 DH's that have some rocks in them. I have one "nice" DH that I haven't ridden in over a year that's just a continous rock garden and last time I rode it was on my brand new Nano's, on my brand new RIP9, got way off line into the really rough stuff, faster than I normally ride the good line and didn't have a problem. However I will state that if I know I'm heading for that trail I prob run close to 30-32 PSI rear.


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## kboykin (Sep 28, 2009)

Wow thanks for the thread. I think I am convinced to drop my ridiculous pressures 

So the lowest recommended pressure on my Maxxis Crossmark tires is 35.

I ride a heavy 32lb fs bike, weigh 200+ with gear and considering that I just got back into mtb after 10+ years of sitting on my arse, I ride like like a loose sack of bricks.

So I'll try 35 on my 26er.


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## Squash (Jul 20, 2003)

*MN, Sounds like you...*

need to keep it just where you are. Everything is a compromise when it comes to tire pressure and what works for you. From the description of your riding style I wouldn't recommend tubeless unless you went full UST tires and wheels, and went with bigger tire, a true 2.35 or 2.4 and possibly DH casings. Tubeless isn't for everyone, there are allot of DH racers out there that won't run tubeless for some very valid reasons. Sounds like with the tires you're using, the terrain you ride on, and the way you ride, you've already found what works best for you. The only way you're likely to be able to go lower is changing equipment a bit. A larger volume heavier duty (read heavier as well) tire would likely let you run a bit lower and avoid rim damage and pinch flats. But if that isn't an option then your stuck. It sounds to me like your in that gray area where going with heavier duty equipment would hinder the rest of the ride, but would be appropriate when the trail points down. You're not flatting every ride, just occasionally. There are some options, but it doesn't sound like you really need or want them. It's one of those things, when your peggin' the fun meter there are times when you are going to exceed the capabilities of the equipment, in this case the tires. So your choices are, change the equipment, or try and keep the meter just off the peg.

Good Dirt


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## kapusta (Jan 17, 2004)

mr.niles said:


> what terrain and how you guys are riding it? shiggy, squash, trailville, lynx, kmacon, kapusta, le duke - how would you describe your riding style?


I would agree with Squash: You've probably found what works best for you.

As I said above, I'm on the east coast, so most riding is pretty rocky and rooty. However, not a lot of sharp racks. Also, compared to a lot of riding in NoCal (I lived in Tahoe for two years and rode a LOT) it is not as fast (lots of tight and technical, instead), and I think speed is a BIG factor. Things in general seemed more wide open out there (as with most places I've ridden out west), with more sharp rocks, and I was not able to run the kind of low pressures I do here. For riding around Tahoe I could get away with around ~27-28 front. I was not running the Big Betty up front when I lived there, so that may have let me go lower, but even with tires with less thick sidewalls (like what I ran out there) I can go down to 25 here in the front no problem.

My riding style varies a lot, but if it is pointed downhill I try to hit it hard. That said, I think I must be a little smooth and/or slow because I seem to get less flats with lower pressure and thinner tubes than most people I know.


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## trailville (Jul 24, 2006)

kboykin said:


> Wow thanks for the thread. I think I am convinced to drop my ridiculous pressures
> 
> So the lowest recommended pressure on my Maxxis Crossmark tires is 35.
> 
> ...


And maybe think about trying some burlier tires. Your description of yourself, bike, and riding style doesn't say lightweight racing tire to me. Get something fatter with a little more meat to it and have lots more fun.


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## kboykin (Sep 28, 2009)

trailville said:


> And maybe think about trying some burlier tires. Your description of yourself, bike, and riding style doesn't say lightweight racing tire to me. Get something fatter with a little more meat to it and have lots more fun.




Didn't realize the crossmark was a lightweight racing tire, yikes! My LBS rides 'em on the same trails and recommended them to me so I got them.

Haven't ridden them much yet, first ride out on them this week I had a small log jump up and lodge into my back wheel bending my der. hanger and the back wheel out of true. Had the pressure at 40+ just because I don't know any better  But they are a LOT better than the ancient crappy tires I was riding on.


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## shiggy (Dec 19, 1998)

mr.niles said:


> what terrain and how you guys are riding it? shiggy, squash, trailville, lynx, kmacon, kapusta, le duke - how would you describe your riding style?
> ...
> 
> ?????????????? what next????


I ride smooth and "light". Started 26 years ago and never owned suspension until 1987. Riding rigid teaches you to pick good lines, be smooth and easy on equipment. Transfer that to suspension and you are even faster. I ride over or around things rather than through them. Trail rider rather than hucker: I jump over things rather than jump off them. I work the bike to keep the terrain from working me.

My local trails are fairly smooth with some rocks, lots of roots, but I do not really change my tire pressures when I go elsewhere, like Downieville or Gooseberry Mesa. I was running 28/30 psi in 2.2" tires on a hardtail with a 80mm fork at Downieville. Was at the front of the group on the lesser-known trails and slipped to the middle when we reached the main routes (I have little local knowledge of them). No flats, no cuts, no dinged rims.

In Utah I ride rigid, 2.2-2.5" tires, 18-26psi. In ~4 weeks (20+ rides) of riding there I had 2 pinch flats: both from slamming rock ledges while not paying attention.

In the early '90s I was at an XC race that used fast, rocky moto trails. I passed many riders on the descents and finished in the top 10% of the field. Afterward the guys parked next to me complained "I was using 50psi and I still flatted!" (and with suspension forks). I was rigid, 2.2', 32psi front; 1.8", 36psi rear (when tires were "smaller"). No flats. Passed people because I could steer around the big rocks rather than bouncing off of/into them.

Even on my Coiler "big hit" bike (6" travel, Marz 66 fork) the pressures are low (and the tires big) and the riding style does not really change. I may take rougher lines and ride off bigger lips but I still do not just plow in and expect the bike to suck it up. Last year I rode one of my favorite sections of trail several times, a 5 mile remote singletrack downhill filled with embedded rocks, big roots and tight lines. First on the Coiler w/2.4" tires, later on my hardtail w/100mm fork, 2.3" tires. Each time I took basically the same lines, took the same time to complete the section and had a blast. I did work harder on the HT, but I did not feel I could have safely gone any faster on either bike. A buddy (riding a fully) following me, commented that I looked like I was on a 5" fully while riding my HT. Smooth and fast.

What next for you? Bigger tires (volume) if you want to try lower pressures. Higher volume generally means you can use lower pressures as long as the tire is still well supported. Every rider is different in what works for them. You either adapt your equipment, or adapt your riding style. If you can do both, so much the better. And remember that with suspension, the tire pressure is as important as the shock settings. Change one and you may need to change the other for best results.

And the real bottom line: If you are fixing a flat, or crashed along the trail, you are not going very fast.


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## LyNx (Oct 26, 2004)

Ah, yeah  That's what they are all right. Definitely a good tyre, but even I know that they're not a tyre suited to the riding style you describe. Try something more beefy like some Schwalbe Big Betty's, WTB MutanoRaptors, Maxiss Ardents, Panaracer Rampages, Kenda Nevegals all in the 2.3-2.4" range.


kboykin said:


> _*Didn't realize the crossmark was a lightweight racing tire,*_ yikes! My LBS rides 'em on the same trails and recommended them to me so I got them.
> 
> Haven't ridden them much yet, first ride out on them this week I had a small log jump up and lodge into my back wheel bending my der. hanger and the back wheel out of true. Had the pressure at 40+ just because I don't know any better  But they are a LOT better than the ancient crappy tires I was riding on.


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## shiggy (Dec 19, 1998)

LyNx said:


> Ah, yeah  That's what they are all right. Definitely a good tyre, but even I know that they're not a tyre suited to the riding style you describe. Try something more beefy like some Schwalbe Big Betty's, WTB MutanoRaptors, Maxiss Ardents, Panaracer Rampages, Kenda Nevegals all in the 2.3-2.4" range.


Depends on which Crossmark. I have a set of 2.25 UST that are pretty beefy and are good trail tires. The standard 2.25 is not bad either.


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## catnash (Jan 14, 2004)

I'm thinking that this thread should become a sticky, as always Shiggy knows what he's talking about...Even now I'm experimenting with pressures and this thread has me reaching for the lower pressures.
What I started with recently was "Eskars performing best at 28-30 PSI whether tubbeless or tubed" MBAction...


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## mr.niles (Feb 5, 2007)

sqaush and shiggy and kapusta, thanks a bunch for the advice and good stories! lynx, i'm going to get one of those pumps to put in my pack when i go into the wilderness areas.

i will most likely stay with my existing setup unless i can find a larger volume tire that has comparable weight, tread pattern, compound to the maxxis high rollers (which i'm having good experiences with right now).

shiggy......."Every rider is different in what works for them. *You either adapt your equipment, or adapt your riding style.* If you can do both, so much the better.'.......i am always attempting to do both, with the emphasis on the later. really this all about having fun, but fun to me is riding the best i can. so i am constantly working on my technique(s). shiggy you have your riding dialed. i agree that a hardtail is a terrific platform to train on in rough terrain. today i did 3 hours of cornering and slalom drills with cones. i have fun doing that sort of thing. it's most important to me to be a good rider. because if i'm a good rider, less than perfect equipment won't matter much, and i'll still have a blast!

once again, thank you all for the help.


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## mr.niles (Feb 5, 2007)

kapusta, thanks for your insite about tahoe. it turns out that tahoe, and especially northstar bike park, are my yardsticks for bike setup and durability. if it can survive a weekend at the star, then it will live thru anything else i am likely to put it thru. also, because i have so much fun riding there, i tend to go looking for places with similar qualities for my rides. so, maybe that is the common denominator for my bike setup. i do make some equipment changes for regular trail riding, but my durability testing takes place in tahoe.

hmmmm.....ok, now that we are talking about northstar, i forgot to mention that i do jumps and hucks on all my bikes, so everything on them has to survive that, too.


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## mr.niles (Feb 5, 2007)

*add wtb prowler xt's*



LyNx said:


> Ah, yeah  That's what they are all right. Definitely a good tyre, but even I know that they're not a tyre suited to the riding style you describe. Try something more beefy like some Schwalbe Big Betty's, WTB MutanoRaptors, Maxiss Ardents, Panaracer Rampages, Kenda Nevegals all in the 2.3-2.4" range.


i have done some serious torture testing of these and they came thru with shining colors - and excellent traction.


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## LyNx (Oct 26, 2004)

Ah yes, my bad, have to try and remember that not everyone is riding a 29er - yet  A guy I sometimes ride with has some 26" x 2.1" LUST Crossmarks and they're definitely a beefier sidewall than the standard version, but I wouldn't put them up for the same duty/terrain I'd trow on a Rampage or Nevegal - for down ehre the Xmark tread is plenty.



shiggy said:


> Depends on which Crossmark. I have a set of 2.25 UST that are pretty beefy and are good trail tires. The standard 2.25 is not bad either.


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## wmalan (Dec 8, 2005)

*Great thread! I had no idea.*

After going through everyone's views, it tells me to move to the "dark side" (lower air)! I was running 35psi front and rear on my Schwalbe Albert 2.25's. I think many of us old school riders do the same mistake. I ride cross country.

I run a 100mm FS bike. I weigh in at 195 without gear. Now I have a Highroller 2.35 rear and Nevagal 2.5 on the front. Both are folding and tubed. Brand new tires.The experimenting should get interesting. 

--
Bill


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## Prophet Julio (May 8, 2008)

*Cool Thread*

There was a thread in here a year or two ago which detailed a study of rolling resistance for mountain bike tires. The basic conclusion was that high pressure worked well on pavement ONLY. Lower pressure created less rolling resistance on rugged terrain. They even had resistance measures for long grass. It was a very scientific undertaking, and got me to run as low as possible.

28 front and back, 175 lbs. Prophet with 150 in the rear shock. Learned on a hardtail, still use that stuff.


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## hikerdave (Mar 8, 2006)

Lugi said:


> I was curious to know what tire pressure is the best for all around xc use?
> I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
> I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
> Any suggestions would be great. Thanks


A lot depends on the shape of the rocks.

In Idaho I pinch-flatted once or twice in about 20 years of riding with 25 psi front and 30 in the back.

Here in Arizona I've pinch-flatted as high as 38 PSI on a true 2.25 tire when I didn't notice a small square-edged rock in time and slammed into it. 36 PSI in the rear is pretty much a guaranteed pinch flat for me unless running ghetto tubeless or true tubeless.

I've even pinch-flatted my front road bike tire at 100 PSI on a small rock, because that rock was crushed gravel and had a sharp edge. (That's what we use instead of grass around here -- we save our water for the golfers  ).


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## shiggy (Dec 19, 1998)

hikerdave said:


> ...I've even pinch-flatted my front road bike tire at 100 PSI on a small rock, because that rock was crushed gravel and had a sharp edge. (That's what we use instead of grass around here -- we save our water for the golfers  ).


And the volume of the tire. The piece of gravel on pavement is also much more likely to cause damage than if it is on hardpan dirt.


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## nbayu (Jan 9, 2008)

a rookie's q:
what is pinch flat? how to determine it? i just heard about the jargon..
TIA


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## shiggy (Dec 19, 1998)

nbayu said:


> a rookie's q:
> what is pinch flat? how to determine it? i just heard about the jargon..
> TIA


Pinch flat


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## clark (Mar 26, 2006)

*As high as possible, without losing traction in the corners..*



Lugi said:


> I was curious to know what tire pressure is the best for all around xc use?


As high as possible, without losing traction in the corners..

that would be 28 to 31 psi.


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## kboykin (Sep 28, 2009)

shiggy said:


> Depends on which Crossmark. I have a set of 2.25 UST that are pretty beefy and are good trail tires. The standard 2.25 is not bad either.


Hmm thanks for the input. Not sure which one I have. They are 2.25, the lesser TPI (60?) and the harder compound.

They seem flimsy to me by touch, but I'm used to cheap old tires so I figured it was not something to judge them by.

I'll just ride them until they destruct. Trails I ride are rocky and rooty single track. Frequently ding my rim and scrape the side of my tires on large rocks and small stumps.


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## LyNx (Oct 26, 2004)

If you had the LUST version, trust me you'd know it  They have a huge a$$ LUST logo on the side in yellow if I remember right, so no mistaking them with the normal ones - _you have the normal casing version.
_


kboykin said:


> Hmm thanks for the input. Not sure which one I have. They are 2.25, the lesser TPI (60?) and the harder compound.
> 
> They seem flimsy to me by touch, but I'm used to cheap old tires so I figured it was not something to judge them by.
> 
> I'll just ride them until they destruct. Trails I ride are rocky and rooty single track. Frequently ding my rim and scrape the side of my tires on large rocks and small stumps.


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## herbn (Sep 17, 2005)

I had forgotten how cool low tire pressure works ,but on a solo wet ride rescently, i let some air out of my tires (not very scientificly)but they worked awesome for a couple of hours , then i got a little carried away on a downhill section and pinch flatted. A pinch flat is a puncture that is on the inside area of the tube, it is not caused by something piercing through the tire ,it's the tube being smashed between your rim and a rock,a snake bite(common expression)is a type of pinch flat that happens with both sides of the rim,you'll have two punctures that always seperated by the width of the rim,the holes tend to look like little slits too not a round shaped pucture that a thorn or nail would make. If you run tubeless at good pressures for wet slimmy conditions you may get burping,when the tires flex to their limit and release a bit of air for a second,you should stop and refill the air as soon as you can , a couple of burps and your tire bead could come totally loose.


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## PainCake (Sep 20, 2009)

Awesome! Just the thread I was looking for. On Friday I ran 40/40 on my first ride on my new rig, (see below). The climbing was great but the downhill....there was this moment. While coming around a left turn at around 25 mph I hit a rock. The front end was propelled about a foot to the right. The bike hooked up immediately but it was still a "moment" and most likely increased my average hr. Sooo, lower presure for the front it is! I'm gping to lower both tires now thanks to this thread.


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## kapusta (Jan 17, 2004)

herbn said:


> I had forgotten how cool low tire pressure works ,but on a solo wet ride rescently, i let some air out of my tires (not very scientificly)but they worked awesome for a couple of hours , then i got a little carried away on a downhill section and pinch flatted. A pinch flat is a puncture that is on the inside area of the tube, it is not caused by something piercing through the tire ,it's the tube being smashed between your rim and a rock,a snake bite(common expression)is a type of pinch flat that happens with both sides of the rim,you'll have two punctures that always seperated by the width of the rim,the holes tend to look like little slits too not a round shaped pucture that a thorn or nail would make. If you run tubeless at good pressures for wet slimmy conditions you may get burping,when the tires flex to their limit and release a bit of air for a second,you should stop and refill the air as soon as you can , a couple of burps and your tire bead could come totally loose.


Snake bite and pinch flat are basically the same thing. A pinch flat is as you describe, but the tube is folded when it gets pinched, so often (but not always) this results in two holes on the same side, of the tube, thus the "snake bite". When it happens on both sides of the rim, that is just two pinch flats (and possibly two snake bites).


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## shiggy (Dec 19, 1998)

kapusta said:


> Snake bite and pinch flat are basically the same thing. A pinch flat is as you describe, but the tube is folded when it gets pinched, so often (but not always) this results in two holes on the same side, of the tube, thus the "snake bite". When it happens on both sides of the rim, that is just two pinch flats (and possibly two snake bites).


And I have never seen the latter in 25+ years of mtbing. It may appear that the snake bite holes are at rim width but they do not line up properly for that to be how it happened if you look at their position on the tube.


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## kapusta (Jan 17, 2004)

shiggy said:


> And I have never seen the latter in 25+ years of mtbing. It may appear that the snake bite holes are at rim width but they do not line up properly for that to be how it happened if you look at their position on the tube.


That's because you ride with people who, unlike me, are smart enough not to try to ride up a concrete staircase with under inflated tires, no finesse, and a really good running start. The double snake bites were the least of my problems.


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## Ruger (Jan 22, 2009)

Read you tires. Most XC tires run optimally at 2 Bar. 29lbs.


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## kapusta (Jan 17, 2004)

Ruger said:


> Read you tires. Most XC tires run optimally at 2 Bar. 29lbs.


You ARE joking, right?


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## shiggy (Dec 19, 1998)

Ruger said:


> Read you tires. Most XC tires run optimally at 2 Bar. 29lbs.


Ummm...I refer you to your own signature.


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## Bullit_cn (Feb 24, 2004)

I run 32 and 35lbs on a Highroller 2.35UST mounted on an XM819 rims on my 2004 5-spot...

my problem is not the traction or pinch flats but rim dents that eventually cannot be re-trued again... :madman: 

I ttry to ride smooth and choose the best line as much as I can but the are time that rocks on the trails cannot be avoided 

What shall I do then???


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## mr.niles (Feb 5, 2007)

*food for thought....*

i recently had a chance to ride some very fun trails somewhere near santa cruz - you know the ones......with perfect soil after a bit of rain, and almost no rocks, i tried lowering my pressures to about 24-25 psi front and about 32-33 psi rear. in that perfect soil, and on those particular trail-side attractions in that place some of you may know about, i got unreal traction with a smooth buttery ride quality.

so, soil conditions will tell you what you can get away with on your pressures. i was able to lower my pressures in sc, but at northstar in tahoe, at 24/32 i'd be pushing my bike down the hill to go buy a new tube.

very cool that this thread is a sticky. it has become very informative.


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## mr.niles (Feb 5, 2007)

kapusta said:


> Snake bite and pinch flat are basically the same thing. A pinch flat is as you describe, but the tube is folded when it gets pinched, so often (but not always) this results in two holes on the same side, of the tube, thus the "snake bite". When it happens on both sides of the rim, that is just two pinch flats (and possibly two snake bites).


either way, your tube is toast, you are pushing your bike, and you are bummed.....


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## scoutcat (Mar 30, 2008)

28psi with conti mountain king 2.4s


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## Dirge02 (Jun 30, 2009)

Wow after reading this thread this may sound crazy, I weigh 150 pounds and I ride my hardtail at 60 psi. I never thought of lowering them, but now I'll give it a try.


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## Rum Runner (Feb 13, 2008)

Here is a quote of mine from another thread (561602)

*I just finished my local series here in the Ottawa area at Camp Fortune and its rough and rocky. Always several guys flatting each race. I switched half way through the season from the Karma to the Nevegals and have since had my best times.

I'm starting to worry less about tire weights and more about traction and running correct pressure. Running tubed 25F/23R on Nevegals 2.1 and 30F/28R on Karmas(2.0) (5'4" 145lbs) with only one pinch flat all summer on a high speed decent having to take a poor line do to some hikers *

Take a few extra tubes when you want to experiment wih tire pressure. Try running lower and lower pressure till you pinch flat and then run 2-4 psi higher after that. Works great for me.
I found there can be a HUGE difference in traction, or rather lack of it, when running your tires at too high a pressure. Of course your riding trails and style could effect optimum tire pressure. Aside from fixing the odd flat it can be fun to mess around with pressure and traction etc as long as you are prepaired for it and it ain't a race haha

Cheers,
Paul


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## FASTK (Oct 26, 2005)

160lbs rider, Niner Rip (29er for those not familiar)

Continental Mountain King 2.4 front 19psi 
Stans Raven 2.2 rear 23 psi
:thumbsup:


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## 411898 (Nov 5, 2008)

I run 35-40 psi in my Nevegals on a full suspension bike.


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## Nikhil42 (Dec 1, 2009)

What would you all recommend for someone 113 lbs?


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## FASTK (Oct 26, 2005)

A good meal! :ihih:


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## shiggy (Dec 19, 1998)

Nikhil42 said:


> What would you all recommend for someone 113 lbs?


Reading the whole thread so you learn how to find your own best pressure.


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## half_man_half_scab (Mar 7, 2006)

I weigh 185 with gear and was getting rim damage on my mavic 819's with tires lower than 45psi in the Sierra Foothills (some of the higher g creek crossings were the offenders). I feel like an idiot for buying UST as the whole point was to run them at low PSI, but that only destroys the wheels. I've been riding this pressure for some time and feel comfortable on it. My next wheels will be tubed for sure.


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## Glide the Clyde (Nov 12, 2009)

Dirge02 said:


> Wow after reading this thread this may sound crazy, I weigh 150 pounds and I ride my hardtail at 60 psi. I never thought of lowering them, but now I'll give it a try.


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## bluebear (Feb 26, 2009)

running at 50 in both tyres  think it's time to drop them to 40 
i'm approx 220lbs so a bit on the heavy side


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## nitropowered (Aug 30, 2007)

As low as you can go fellas. That low pressure squirm can be unnerving at first, but you will get a handle on it and you will be railing corners faster than ever.

I love seeing newbs (and even better, vets) running their tires rock hard and they wonder why they don't get traction, while on the other hand they point out my tires are nearly flat


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## Rum Runner (Feb 13, 2008)

I run Kenda Karmas(2.0) and Nevegals(2.1) and even tho the Nev is about 200g a tire heavier my times are about the same on both tires. I run 28 ish on the Karmas and 23 ish on Nevegals. I get WAY more traction on the Nevs.
I think my best time ever (on local track) was on the Nevs, but was later inthe season and was probably fitter 

Anyone else find they like racing on a larger volume tire with lower pressure even with the weight penalty???

Cheers,
Paul Bell


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## h82crash (Dec 24, 2009)

This all makes sense but for clydes like me @ 245 it seems like a trade off. There was mention of speed but not much about rolling resistance. When I ran 28/38 which seemed to give me plenty of support, the confidence and traction on the trail was huge. The trade off is it felt like I was riding through a foot of molasses on a relentless uphill with a headwind. If this were my first day out, I probably wouldn't think MTBing was very fun. I'll admit the RR was not as bad in the dirt as it was on pavement. For me, it seems the low pressure is more approriate for downhill. I'm riding with more pressure and slowing for the technical stuff.

Edit: Ok, went for another ride and realized I _was_ riding uphill with a headwind. Santa Ana's for the last few days. Yes there was noticeable rolling resistance but not too bad. This time pressure @ 20/30. Front is fine but I think the rear needs some more air and the tires stick like velcro. In fact, the tires grip so well the there IS more resistance on pavement.


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## catnash (Jan 14, 2004)

Old habits die hard, it's a great thread to convince you to try lower. 

Recent rides on my own no problems in the dry, with a group on a littered trail of shale, wet and muddy and underlying smooth and square fist sized rocks. The bike felt quite harsh. It makes you realise even 3-4 Psi too much can affect handling. this from a rider 155lbs on Maxxis minion 2.35 so looks like 22 Psi give or take seems ideal as 25Psi on that track felt very scary.
One of the biggest mistakes i have done over the years is not spent the time out in the field shock pump tyre gauge and a series of loops.


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## want to ride (Mar 2, 2008)

*Same thing here..*

I went tubeless on my new bike two weeks ago.
I set the tire pressure 25-28 front and rear then went for a ride....
I just kept reducing the pressure until the handling felt perfect to me.
When I got back to the car I checked the pressures and I couldn't believe it.
20 psi in the front and 23 psi in the rear. I'm running Specialized Fast Traks 2.0 front and rear.
I'll do the same thing tomorrow just to make sure! :thumbsup: 
Climbing cornering even flat out hammering just felt effortless.
Low pressure really makes a difference!
Oh I'm 155 pounds with gear.
Spend time to play with the pressure and go with the feel.


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## Combatcm (Nov 15, 2005)

I run 40/40, im also 210..I always worry about pinch flats riding hard. I pump them to 40 then stop worrying about messing with pressure.

I have used the mythos tires before and i got a lot of pinch flats with them..they also wore really fast. They are very good tires with lots of grip and they are very light.


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## twenty6black (Jan 12, 2009)

recently ran 17psi in 2.1 Renegade's on a wider rim (Easton Haven)...it was a wierd ride - if i was super smooth everything was good. But, if I gave some serious input then the tire squished too much and I could feel some roots hit.

So the deal is, with UST run low psi until the above starts happening. 1.5bar, and 21psi are magic numbers for bigger tires.

I am 180lbs, so I am heading 24psi in the front, 25-26psi rear. These lower PSI's give more traction and thus you can run a lower hieght knob, and a faster wider tire.

To the people that WONT GO TUBELESS, then they are at a dead end, I would say they can only go down to 30psi with a bigger casing and 35psi with a 2.0 sized tire...and thats only at my 180lbs wieght....any heavier then up the PSI.

later...LC

PS: UST rims, and any tire with sealent works - Guetto tubeless add 5-10psi just for reliablity!


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## shiggy (Dec 19, 1998)

twenty6black said:


> recently ran 17psi in 2.1 Renegade's on a wider rim (Easton Haven)...it was a wierd ride - if i was super smooth everything was good. But, if I gave some serious input then the tire squished too much and I could feel some roots hit.
> 
> So the deal is, with UST run low psi until the above starts happening. 1.5bar, and 21psi are magic numbers for bigger tires.
> 
> ...


No, it depends on the rider, tire, rim and terrain. I am currently running Panaracer GC CX 2.1s with tubes on 24mm rims under 25psi on hardpack to rocky terrain.180 pounds, hardtail bike. I can go lower with wider rims.

I do/can not go lower with similar volume tubeless tires.

p.s. Not all DIY conversions work. Standard tires without tubes require more pressure to prevent squirm. Use at your own risk.


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## Rum Runner (Feb 13, 2008)

twenty6black said:


> To the people that WONT GO TUBELESS, then they are at a dead end, I would say they can only go down to 30psi with a bigger casing and 35psi with a 2.0 sized tire...and thats only at my 180lbs wieght....any heavier then up the PSI.
> 
> later...LC


Hey LC, I have to disagree with going tubeless is the only way to go. rft:

I run tubes and I don't have a problem running low pressure. As I stated earlier in the post I am 140ish with a 30ish lb XC bike. I have been running 2.1 Nevs @ 23 ish pounds the end of last racing season and now this season. I am not getting any more flats(very rare) compared to the tubless guys (flatting or burping) in my group. I can see that I am not spinning any more than the tubleless guys. I clear tough sections (without flatting) and I am one of the newest guys in the group.

IMHO key things are TERRAIN---RIDER WEIGHT---RIDING STYLE combined .
If you are not willing to experiment with pressure and changing the occational flat then pump em up to the sidwall specs and go, with a trade off on traction, comfort, and possibly speed.
Maybe this is a good argument to go tubeless(if you just want to pump em up and go)( I believe sidewall pressure specs are lower for tubeless tires ???YES/NO???)

Cheers,
Paul


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## gvs_nz (Dec 13, 2009)

twenty6black said:


> recently ran 17psi in 2.1 Renegade's on a wider rim (Easton Haven)...it was a wierd ride - if i was super smooth everything was good. But, if I gave some serious input then the tire squished too much and I could feel some roots hit.
> 
> So the deal is, with UST run low psi until the above starts happening. 1.5bar, and 21psi are magic numbers for bigger tires.
> 
> ...


Depends on your terrain and style of riding.I'm 170 lbs, I ride forest trails[ no rocks or thorns] and have been riding tubes at 25 psi for 15+ years. One of my current fav tires for some conditions is a Nobby Nic 2.4 snakeskin. It gives best traction when run on the front 28mm rim with a tube at 20 psi.Ghetto tubeless I would probably run it 23 to 25 PSI[ no support from a tube].


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## gvs_nz (Dec 13, 2009)

Some useful info on tire pressures and rolling resistance here

http://www.schwalbe.co.uk/shopdata/files/TechInfo2-GB.pdf


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## selin (Nov 20, 2009)

*Is my pump gauge ok?*

I didn't bother about tyre pressure until I read some threads and bought a full rigid 29. The absence of suspension fork drove me to low pressures. 
I don't have a gauge to measure the pressure at trails. At my first ride I reduced the pressure to the point I felt the bike rolling smooth; I was sure I could go lower without worrying about pinch-flats or damage the rims. When I returned home I checked the pressure at Nevegals 2.2 and my floor-pump gauge show 15psi front and 18psi rear  (I know pump gauges are not so accurate). My weight is 158lbs (72kg). 
With my old 26 ht I was running my tyres at hight pressures and its ride was so harsh! Now I know how important is the "right" pressure in tyres. Maybe the right pressure is different for everyone but don't be afraid to try lower pressures, you will be surprised  .


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## twenty6black (Jan 12, 2009)

*tubeless stuff*



gvs_nz said:


> Depends on your terrain and style of riding.I'm 170 lbs, I ride forest trails[ no rocks or thorns] and have been riding tubes at 25 psi for 15+ years. One of my current fav tires for some conditions is a Nobby Nic 2.4 snakeskin. It gives best traction when run on the front 28mm rim with a tube at 20 psi.Ghetto tubeless I would probably run it 23 to 25 PSI[ no support from a tube].


yep...the above are good guidelines....everyone jumps into (onto) the tubeless topic - love it!

Here is something that just happened to me....mud race had the Easton Haven's 21mm rim width, with 2.2 MK SS run them tubeless, so I can go low on the pressures - ANYWAY....didnt lower the pressure for the race - ended up runing 30+psi in the front and 35+psi in the rear !!! I kenw there was a problem right at the start - i could feel every rock and root.

sooooo...I took it easy on the rock and roots - thing is, the mud sections I was getting good grip - knobs digging through to hard soil - and the double track BAAM - major speed!

So the MK 2.2 clears the mud and digs for traction, and when run at higher pressures (higher for me) they roll amazingly fast.

I have also run them at lower pressures and the traction goes UP - speed on hard pack goes down a wee bit.

This race turned out good - more from good luck than good management.

...LC(cheers)

PS: lesson is, higher pressure on a kobby tire are cool for mud events!


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## Tillers_Rule (Sep 11, 2004)

I run 50 psi front and rear on a Stumpjumper. I'm 215 with gear.


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## Dazed (Feb 7, 2004)

I'd like to chime in. Everyone who hasn't gotten that high volume tires and low pressure is the way to go by now, really should wake up and leave 1994. 

I weigh 215# without gear on, and I run 22psi in the rear and 18 in the front on trails with my FS with Big Betty 2.4's, and 25/23 psi on fire roads/pavement with my hardtail and Rocket Ron 2.4's. I roll faster than the 2,0" 
semi slick guys with their 50 psi pressures (off the tarmac at least), and have way more comfort.


With tubes, but on XTR Flow and Crest rims. I can't remember my last pinch flat. Must be years ago.


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## Turveyd (Sep 30, 2007)

I find your weight is generally proportionate to your hand strength and therefore I use the it's soft enough to get a good squeeze on the front and only a moderate squeeze on the front 

This the lower the better mentality started from the Stan's users is well ridiculous, yes you can run it that low cause of no pinches but you've got to run it harder than with tubes cause 1 less layer of rubber, and ran really low, tires squirm, side walls give out randomly causing a sharp fall over sensation or even a fall over.

That and modern tyres the casing is so soft, if you run them flat the knobs fold in on contact with the ground and you might aswell be running slicks, and slicks ran low on rocks / road would still out grip mtb tires, until you hit mud.


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## Turveyd (Sep 30, 2007)

Dazed I'm your weight and with a tougher higher volume tire ( RQ 2.4 ) with a fat rim ( EX729 ) I get 24psi, 22psi I can feel the roots hitting the rim, 26 and it feels rigid ( the effect of HUGE tires ) no way can I get near 18 on the front without it feeling like it's flat.

Obvously you have to allow hugely for guages being really in accurate at these kinds of pressure.


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## Dazed (Feb 7, 2004)

Turveyd said:


> Dazed I'm your weight and with a tougher higher volume tire ( RQ 2.4 ) with a fat rim ( EX729 ) I get 24psi, 22psi I can feel the roots hitting the rim, 26 and it feels rigid ( the effect of HUGE tires ) no way can I get near 18 on the front without it feeling like it's flat.
> 
> Obvously you have to allow hugely for guages being really in accurate at these kinds of pressure.


I have two standalone gauges (Schwalbe Airmax Pro and Topeak Shuttle Gauge), and I know what I feel. I may not ride very rough, but I don't flatten the tires.

I doubt the RQ is any bigger or sturdyer than a BB. My tires aren't squirmy at all. The RoRo's would be at that pressure, but not the BB's.

It's a very individual thing, of course.


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## Turveyd (Sep 30, 2007)

The RQ2.4 is the biggest volume tyre I've seen and with 180tpi in the side walls ( Apex casing ) it's pretty solid aswell, the 29mm internal DH rim helps aswell.

Shame there so expensive, but no visible wear on mine on the front so not really a worry if I can get a year out of it.


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## Dazed (Feb 7, 2004)

Those wide rims make a difference of course, even though the flows have Stan's "BST" bead hooks ( https://www.notubes.com/images/height-compare.gif )adding to the width and volume, 29mm is WIDE.

Shiggy / mtbtires.com backs you up on the RQ being bigger, btw. Too bad, 'cause i don't think my Ventana frame can deal with ANYTHING bigger than the BB.  ...And now I know something bigger exists!


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## h82crash (Dec 24, 2009)

I don't have issues with pinch flats and I have dropped my pressure based on this thread. Can't honestly say the RR is less with lower pressure. I recently showed up to a group ride (a really fast XC group) with my all mountain/rocky trail pressure and I very soon got a "you better put some air in your tires." from folks that just looked at my tires. Took like 50 psi rear to get them as firm as the rest of the group. Kept front to about 30. Wow, what a difference! I still couldn't keep up with them but it didn't feel like riding velcro tires on carpet anymore. I'll drop back down for my regular rocky bombing but for the XC stuff, I'm checking to see if some road wheels will fit. 

Most of the group were running 1.95s and few were larger than 2.1. Maybe "all around xc" is different from serious xc race?


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## Turveyd (Sep 30, 2007)

Dazed, I run the RQ 2.4 in a 29er fork so loads of room  Not many regular forks they'd work in, front only aswell I'd say, to draggy on the rear for me.

I actually bought it to run with my Rigid bike, which uses the 29" wheel and a Ardent 2.4 ran soft ish, although not as big it still handles roots and rocks rigid better than the RQ2.4, but the RQ2.4 out grips it.


Seriously pressure sensitive from roots hurt to you can't feel the roots with just the smallest amount of air let out, then to the jarring rim contacting sound no pinches yet though. and I bust my right thumb 2 weeks back so my own gauge is off


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## Dazed (Feb 7, 2004)

No gauge, huh... Well, I was surprised how "hard" 20 psi feels in a whooping big 2.4" tire. maybe you'll find that you're actually running lower pressures than you think if you check with a good gauge?


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## Turveyd (Sep 30, 2007)

Mates got a gauge though, as I state your gauge very likely isn't accurate, it's obviously means the same for my mates.


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## Dazed (Feb 7, 2004)

And as _I_ stated, I've got several gauges showing the same pressure.


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## skiwi (Mar 8, 2010)

Just discovered this thread. It is interesting that no-one has actually stated the physics first.

1. For a given tyre pressure your contact patch size will stay the *same* regardless of the tyre size. Read that again. So a 2.5" tyre will have the same contact patch area as a 1.9" tyre @30psi, or @25psi or whatever.
2. What will change with changing tyre size is the *shape* of the contact patch. The wider the tyre, the shorter and fatter the contact patch. But the size will stay the same.
3. With the changing *shape* of the contact patch, the dynamics of the tyre will change in the 4 axis that a tyre works on (the "friction circle") - front and rear for traction/braking, and side-to-side for cornering.
4. Generally speaking chose a narrow long contact patch for better traction & braking, and a wide short patch for cornering.

That is the physics.

What is also true, as someone has stated is that at lower pressures a tyre will deform to absorb a small obstacle where a tyre at higher pressure will resist deformation and ride up over the obstacle. Whether this is a "good thing" depends on the terrain, the speed and your objective.

At one extreme, hard-packed surfaces, you work to present the smallest contact patch that you can. Using smaller tyres and higher pressures. There will be nothing faster. That is why roadies run 19c tyres @130psi for races.

For other terrain, you need to balance speed, traction, cornering and braking to find the right combination to go fastest. This will be a combination of tyre size, pressure and tread pattern. There is no hard-and-fast rule here. You will find some tyres will be faster at higher pressure than other tyres run at lower pressure when sense says they shouldn't be. Why? Because the tyre manufacturer has developed a casing optimised for the conditions you are riding, and the tyres are fast.

For this reason, I work on tread/compound first, size second, then pressures third.

However, I have about 20 tyres in the garage and 3 sets of wheels setup. One with a general XC tyre-set, another with a more radical XC race set, and one with a wide software "traction" set for wet weather.


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## Rum Runner (Feb 13, 2008)

> What is also true, as someone has stated is that at lower pressures a tyre will deform to absorb a small obstacle where a tyre at higher pressure will resist deformation and ride up over the obstacle. Whether this is a "good thing" depends on the terrain, the speed and your objective.
> 
> At one extreme, hard-packed surfaces, you work to present the smallest contact patch that you can. Using smaller tyres and higher pressures. There will be nothing faster. That is why roadies run 19c tyres @130psi for races..


I think it is said that you loose more energy in the vibration and bouncing of the bike from a *harder* tire (from pressure) than you do from the energy lost deforming a *softer* tire over a bump. 
It must also be noted that there is optimum tire pressures for road tires. Its not pump them up to next to the blowing point. For example at my weight my tire pressure for my Michilen Race is around 90 psi, while a heavier rider needs more.

It's also funny how all your theories get thrown out the window buy smoking your best time running the bigger heavier tire with lower pressure(Nevegal 650g) on a day when its dry and fast and you figured being to lazy to switch to the lighter higher pressure tire (Karma 400g) was gong to hurt you :madman: :madman: :madman:


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## trailville (Jul 24, 2006)

Actually, based on my analysis of the physics involved, I found that I had a larger contact patch when running skinnier tires at high pressure. This was due to the fact that my feet were touching the ground far more often.


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## skiwi (Mar 8, 2010)

Rum Runner said:


> It's also funny how all your theories get thrown out the window buy smoking your best time running the bigger heavier tire with lower pressure(Nevegal 650g) on a day when its dry and fast and you figured being to lazy to switch to the lighter higher pressure tire (Karma 400g) was gong to hurt you :madman: :madman: :madman:


That is also a point that is worth re-affirming. It is very very hard to have a consistent measure to evaluate tyre/wheel performance against. A long time ago I setup a trial of aero rims as a few of my mates and I were deeply into triathlons. We have a evaluation circuit of about 5 klicks taking in a variety of types of surface, hill, flat and downhill (obviously). We were all very fit and strong, and yet there was about 5% variability in our circuit times on the same day, on the same equipment. It makes it very hard to scientifically measure with the "control" being so variable..

I would also state the obvious. Feeling fast and being fast against the clock are different things...


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## skiwi (Mar 8, 2010)

trailville said:


> Actually, based on my analysis of the physics involved, I found that I had a larger contact patch when running skinnier tires at high pressure. This was due to the fact that my feet were touching the ground far more often.


I think the key point for the physics is whether your training wheels are on or not???


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## gvs_nz (Dec 13, 2009)

skiwi said:


> Just discovered this thread. It is interesting that no-one has actually stated the physics first.
> 
> 1. For a given tyre pressure your contact patch size will stay the *same* regardless of the tyre size. Read that again. So a 2.5" tyre will have the same contact patch area as a 1.9" tyre @30psi, or @25psi or whatever.
> 2. What will change with changing tyre size is the *shape* of the contact patch. The wider the tyre, the shorter and fatter the contact patch. But the size will stay the same.
> ...


Mfg have released snippets of their research over the years which are counter intuitive to the "Physics" as we thought we understood it. XC World Cup podium finishers using 2.4 tires have a little more info at their fingertips than we do.

When comparing different width tires it's not the size of the contact patch which governs rolling resistance but the shape. It's related to hysterisis not friction.

When considering construction of tires and their rolling resistance the physical tread blocks have an affect but are secondary to the underlying tread region of the casing.

Whether on or off road, there is trend towards wider tires having less rolling resistance. Aerodynamics aside, a 25mm road tire, even at 120 psi, has been shown to have 40% less rolling resistance than 19 mm road tire at the same pressure. A 1.7" tire at 60 psi has the same rolling resistance as a 2.4" tire at 30 psi. The rougher the ground the greater the effect. As much as 50 watts can be gained on rough terrain using the 2.4" tire at 23 psi over the the 1.7" tire at 60 psi.


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## mr.niles (Feb 5, 2007)

just fyi....i was involved in this thread a while ago. after plenty of riding various tire pressures on maxxis high roller 2.5 dh casing tires, i'm at 27 front and 35 rear on my dh bike. any lower and i flat. of course this is one rocky terrain which is at my local bike park. traction and rolling resistance don't mean anything if your ride gets delayed because of flats. a recent trip to downieville showed me i'm right on with my pressures because i didn't have to stop and fix flats like other guys in our group (i ran 28/36 just in case) - it makes a run much more fun when you don't have to fix your bike half way thru it! just sayin'....


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## trailville (Jul 24, 2006)

mr.niles said:


> just fyi....i was involved in this thread a while ago. after plenty of riding various tire pressures on maxxis high roller 2.5 dh casing tires, i'm at 27 front and 35 rear on my dh bike. any lower and i flat. of course this is one rocky terrain which is at my local bike park. traction and rolling resistance don't mean anything if your ride gets delayed because of flats. a recent trip to downieville showed me i'm right on with my pressures because i didn't have to stop and fix flats like other guys in our group (i ran 28/36 just in case) - it makes a run much more fun when you don't have to fix your bike half way thru it! just sayin'....


And if the title of this thread wasn't "Tire pressure for all around *XC riding*", that would be a good point


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## skiwi (Mar 8, 2010)

gvs_nz said:


> Mfg have released snippets of their research over the years which are counter intuitive to the "Physics" as we thought we understood it. XC World Cup podium finishers using 2.4 tires have a little more info at their fingertips than we do.
> 
> When comparing different width tires it's not the size of the contact patch which governs rolling resistance but the shape. It's related to hysterisis not friction.
> 
> ...


I'd be interested in having a look at this research. Do you have any of it?

Also, for your example of a road tyre, there are no tread blocks to complicate factors. There is certainly compound and construction - which are significant variables - witness pro motorsport. But you can't beat the physics.


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## mtb63 (Apr 14, 2008)

I'm 230 lbs and run 45 psi rigid or suspension and I never get flats. You should not get flats when you ride. I see so many posts about running 20ish psi and you they always get flats - like it's accepted or something. Yeah, it's a little rougher - my god you're on a MOUNTAIN BIKE. I tried 40 psi the other day and that was ok but I really like to the tight feel of a properly enflated tire.


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## Rum Runner (Feb 13, 2008)

I vary my pressure with the trail and the gang I am with. When I go on trails with very technical climbs and a bunch of good riders I tend to go as low as I think is safe and go 2 psi lower 

I usually do well clearing technical stuff while other sometimes get stumped on a slippery steep uphill section. I'd rather have to fix a flat sometime during the ride but be the only one to clear a tough section cause I was the only one with traction 

I do this cause they usually smoke me when its fast (doh)

I'm around 140lbs, on FS 30lb GT, Running Nevs 2.1 @ 22-25psi with tubes for fun technical group rides. 

Cheers,
Paul


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## Tillers_Rule (Sep 11, 2004)

I was running 50/50 for years on 2.1 tires front and rear. I swapped over to a 2.35 front and dropped psi to 35 front and 45 rear. There's a bit more rolling resistance, really feel it on the ascents but there's also much more bite on the descents and overall I'm pretty happy with the lower psi.


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## trailville (Jul 24, 2006)

Rum Runner said:


> I vary my pressure with the trail and the gang I am with. When I go on trails with very technical climbs and a bunch of good riders I tend to go as low as I think is safe and go 2 psi lower
> 
> I usually do well clearing technical stuff while other sometimes get stumped on a slippery steep uphill section. I'd rather have to fix a flat sometime during the ride but be the only one to clear a tough section cause I was the only one with traction


:thumbsup: 
Cleaning steep techy climbs is under-appreciated by too many riders. I mean, anybody can ride downhill (though some may need to go slower than others). But you make a tough climb, and you know you accomplished something.


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## Turveyd (Sep 30, 2007)

trailville said:


> :thumbsup:
> Cleaning steep techy climbs is under-appreciated by too many riders. I mean, anybody can ride downhill (though some may need to go slower than others). But you make a tough climb, and you know you accomplished something.


I agree, going fast down is simply a matter of having a less risk perception to what your doing where as climbing is a partial skill.


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## Noclutch (Jun 20, 2010)

OK- dumb pressure question, tire selection aside and assuming same tires, same trails, same bike-
As things get drier and looser on the surface on your usual trails, especially sandy soil riders, do most increase or decrease pressure to gain more traction? What about increased foliage, esp pine needles(aka slippery bastards)?

I can make a theoretical argument both ways in my head, but it's quite empty in there


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## skiwi (Mar 8, 2010)

*repeat post*

wouldn't is be nice to be able to delete a post that isn't in the right place in a thread?


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## skiwi (Mar 8, 2010)

Noclutch said:


> OK- dumb pressure question, tire selection aside and assuming same tires, same trails, same bike-
> As things get drier and looser on the surface on your usual trails, especially sandy soil riders, do most increase or decrease pressure to gain more traction? What about increased foliage, esp pine needles(aka slippery bastards)?
> 
> I can make a theoretical argument both ways in my head, but it's quite empty in there


General rule is to lose pressure. As you release air, the tyre footprint increases and the bigger contact patch will float more over the loose stuff. Only exception to this rule is for deep mud when the ability to cut through the mud helps traction (hence narrow tyres with sharp knobs).


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## skiwi (Mar 8, 2010)

mtb63 said:


> I'm 230 lbs and run 45 psi rigid or suspension and I never get flats. You should not get flats when you ride. I see so many posts about running 20ish psi and you they always get flats - like it's accepted or something. Yeah, it's a little rougher - my god you're on a MOUNTAIN BIKE. I tried 40 psi the other day and that was ok but I really like to the tight feel of a properly enflated tire.


With your weight, you must use higher pressures. However, you lose traction with the higher pressures as your contact patch is smaller. Not a big issue downhill (might even help), but uphill, it's not good. In XC also generally slower. However there is a point when you need to add air to go faster....


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## mattotoole (Jan 26, 2009)

About the "time to leave 1994" comment, many of us are still riding that way -- on a 26" hardtail. 

Currently I'm running 35f 40r on 2.1/1.9" tires. This feels pretty good all around, including the 8-12 road miles each way to/from the trails. If I go lower, I get pinch flats in the rear and the front slips around the rim under braking, threatening to shear off the valve stem. 

Next tires will be 2.2 or 2.4 for sure, now that we can get fast tires in that size (Ralphs, Saguaros, etc.) If they slip I'll glue 'em on, but probably not go tubeless as that's still too fussy for me.

In the early 90s, Specialized made a 2.5" Ground Control, which we all thought were the cat's pajamas and surely the Next Big Thing. But most riders believed that skinny/light = fast, and few frames could accommodate these tires so they were a non-starter in the marketplace. Same with Ritchey's 2.3" Zmax, and I think Fisher made a 2.5" tire too. The cool kids at the time wouldn't be caught dead on them.


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## bquinn (Mar 12, 2007)

Since this thread is about XC pressure and not rocks/technical stuff, I have a ? for you FAST XC guys out there.

My friends and I that are pretty quick on the trails can NOT run lower pressure than about 30psi in the front without rolling the front tire. The rear does the same at close to the same pressure. Now when I go on a road trip out west in the rock then I run ~24psi no problem. But I'm talking about fast single track that is pretty hard packed and cornering FAST. 

Now I know that there are lots of variables to consider like rim width, tire casing stiffness, size of tire (especially compared to rim width)....etc. I am currently running 819's with a WTB Weirwolf 2.3 UST on the front, Maxxis Advantage LUST 2.1 in the rear. Same results with a few other tires as well. Results are the same with either tubes or UST.

So I would like to hear input on guys who can truly corner fast on more hard packed trails. What tire sizes, rim width, and finally what pressure. I you don't know exactly what I mean about the tire rolling then you aren't cornering fast enough to understand.

thx


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## trailville (Jul 24, 2006)

bquinn said:


> Since this thread is about XC pressure and not rocks/technical stuff, I have a ? for you FAST XC guys out there.


Since when is rocks/techy stuff not XC?



bquinn said:


> I you don't know exactly what I mean about the tire rolling then you aren't cornering fast enough to understand.


Good one. Most of my riding is on slower techy singletrack, but if I'm riding somewhere that I know has faster track with turns I'll up the pressure just for that reason (the squirrely feeling you get when your front tire rolls sideways). Every bike setup decision you make is some type of compromise. But it is different for different tires.


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## Dion (Oct 22, 2009)

Holy God, you guys run some high pressures...

I went on a quest to find the fastest rolling tires possible, and first went with Small Block 8's, then tried Gaex Sagauros - which I have both on my 26" and 29'er rigids. Both fanatastic tires and mounted up tubeless with ZERO problems - no burping, even on incredibly rocky terrain - I believe I have 2.35's on both bikes. I ride the trails 5-7 days a week, and I ride to the trails (none of that driving garbage). Sometimes I'll cover 20 miles+ of asphalt on my mountain bike if I want to go explore more. 

I am 210-215lbs and I run 22-26 psi most of the time, usually higher in the rear tire. Before I leave the house, I start at 30psi, and adjust at when I get to the trail. If it's hardpacked and smooth - there's no need for adjustment. When I check it after the ride, I will find I am down to the 22-26 range in most cases.

On my tubeless 'cross bike, I change the tire pressure depending on the course, but I start at 40psi and go down from there. 'Cross racing is a whole different beast.

I pretty much ride XC most of the time, but I do throw in the technical stuff almost every ride. Climbing rocks I can definetely feel the difference when I have too high of pressure. Doesn't affect my XC riding, either: whatever that means, but it looks like my rock climbing doesn't including fast XC. Again, I think I found the fastest rolling tires for my trails.

IMO, it's hard to get a true answer for your situation. I think talking to the local racers in your neck of the woods and asking them their set-up would be the best direction to go, or ask your LBS what the sweet set-up is. IMO, it's very regional specific. I bet my set-up would suck for more humid areas like Florida and in the South. For Nor-Cal, my set-up works like a charm.


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## bquinn (Mar 12, 2007)

Dion said:


> IMO, it's hard to get a true answer for your situation. I think talking to the local racers in your neck of the woods and asking them their set-up would be the best direction to go, or ask your LBS what the sweet set-up is. IMO, it's very regional specific. I bet my set-up would suck for more humid areas like Florida and in the South. For Nor-Cal, my set-up works like a charm.


This is a great point Dion. XC means so many different types of terrain depending on the area of the country you live in. I for one have no rocks, no steep technical climbs, just fast single track in the woods that can be very hard packed (sometimes completely solid if it's been dry like all fall here). For that circumstance I can't imagine running mid to low 20's while cornering fast if my tires start rolling at ~29-30lbs.

My LBS which has some well qualified riders, including the owner which has mounds of race trophies on his walls can't run less than 32lbs or he runs into the rolling issue. Another rider is at 45lbs F/R and neither understand how it would be possible to run the low #'s. I'm sure there are other riders on this board that have hard packed single track and run into this issue and was hoping with some time I would hear from them.

I didn't mean to be snotty about the 'actually fast' comments, but I've learned over time that many riders that claim to be fast are far from it when cornering, and I need experience/comments from those that truly are.

thx


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## skiwi (Mar 8, 2010)

Dion said:


> Holy God, you guys run some high pressures...
> 
> I went on a quest to find the fastest rolling tires possible, and first went with Small Block 8's, then tried Gaex Sagauros - which I have both on my 26" and 29'er rigids. Both fanatastic tires and mounted up tubeless with ZERO problems - no burping, even on incredibly rocky terrain - I believe I have 2.35's on both bikes. I ride the trails 5-7 days a week, and I ride to the trails (none of that driving garbage). Sometimes I'll cover 20 miles+ of asphalt on my mountain bike if I want to go explore more.
> 
> ...


Certainly for your type of riding, in fast hard-pack conditions hich pressure is the way to go. Just like road riding, small contact patches are fast when traction is not an issue. I assume that you use low-knob tyres as well? Furious Fred or Small Block8?


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## gvs_nz (Dec 13, 2009)

You must be really fast to roll your tire off your rim on single track with 30 psi. Check the downhill threads and guys are generally running same or lower pressure than you. Or is it just you do night like the feel of the tire squirming?


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## Dion (Oct 22, 2009)

skiwi said:


> Certainly for your type of riding, in fast hard-pack conditions hich pressure is the way to go. Just like road riding, small contact patches are fast when traction is not an issue. I assume that you use low-knob tyres as well? Furious Fred or Small Block8?


I ride Gaex Sagauros on both my 26" and 29er. I ride both bikes rigid and it is very, VERY bumpy and rocky on the trails I ride daily. Baseball sized rocks that will shake a dental filling loose. If it was smoother, I probably would run a bit of a higher pressure - like today I'm riding in Santa Cruz and will inflate my tires a bit.

Believe-you-me, I've spent a lot of money and fiddling around with tire pressures with lots of different tires and lower pressure/fast rolling small knobs works great for me.

I doubt it would work as well in other parts of the country, though.

I run higher pressures on my 'cross bike when I train for racing, understanding I'm not going to be riding on MTB trails and I need a little more speed.


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## happydog500 (Sep 29, 2006)

I agree it's a personal thing. I use 60psi and roll a lot faster then my friends. In fact, I cost past them while there pedaling.

Chris.


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## shiggy (Dec 19, 1998)

happydog500 said:


> I agree it's a personal thing. I use 60psi and roll a lot faster then my friends. In fact, I cost past them while there pedaling.
> 
> Chris.


And how does 60psi work on Devils Gulch? Still faster than your buddies? Able to stay on the trail?


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## happydog500 (Sep 29, 2006)

Works supper good!! Twice I hit hard but its fast coming down!! If you go up the gulch (actual trail, not mission creak) you'll spin in a couple areas, but other then that its fast.

Chris.


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## gvs_nz (Dec 13, 2009)

happydog500 said:


> I agree it's a personal thing. I use 60psi and roll a lot faster then my friends. In fact, I cost past them while there pedaling.
> 
> Chris.


 You gotta be trolling for a bite. You got one.

Is this based on experience through using large volume tires at lower pressure and then reverting back to skinny tires at roadie pressures? Coasting at high speed on smooth surfaces has a lot, if more, to do with aerodynamics.

I can say the same thing about about coasting down trails while on race kings behind guys on skinny tires at ridiculous pressures bouncing all over the place.
Take a look at some of the current[ not 1990]world cup vids and see if you can see anybody on skinny tires at high pressure. Some are running 2.4's and they are big 2.4's.

Xmas is coming, do your joints and back a favour by buying a Race king 2.2 and set it just above squirm pressure and feel what smooth speed is, not perceived speed. Do back to back timed tests with your current set up then post back to us. I'd be very surprised if you still stuck to your current set up.


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## trailville (Jul 24, 2006)

60psi, Wow. 
I don't even run 60psi in my 700x35 cross tires on my touring bike.


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## happydog500 (Sep 29, 2006)

I am not trolling for anything. I speak from the hart, with genuine questions. If I ride from Arlberg Sports parking lot, up twin peaks, down stairway back, I guarantee most of the ride, the rolling resistance is not "perceived" but an absolute fact that can easily, or very easily be felt (_Typical for me; Mountain Bike ride, but is mostly pavement_).

Not last year, but the year before, all summer I trained on my Mountain Bike, from downtown Wenatchee, to Mission Ridge. I'd go off and do a trail ride, then back to pavement, without stopping to take air out, then to put air back in.

I do a lot of rides where most people drive to the trail. I RIDE TO the trail, then on the trail, then back to the road. I ride a mountain bike, on the dirt, but am actually on pavement most of the time (instead of driving to trail, I ride bike).

If I go down Devils Gulch, I ride back to Wenatchee, not drive back. Some ride up, stop, change the seat height, change air pressure, waist a bunch of time fooling around with there GPS's. Get to the rode, change air pressure, and seat height.

My preference is to set the bike up. Ride to the trail, ride the trial, ride back without having to make a bunch of adjustments.

I did change pressure down Freund Canyon last year. With the heat from braking the pressure was a little high for the jumps on the downside.

I think the difference is that most who ride the dirt, that day just ride dirt. My dirt rides are mostly pavement. So where not really compairing the same thing when I say I ride with 60psi 'on the dirt.'

Chris.


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## happydog500 (Sep 29, 2006)

trailville said:


> 60psi, Wow.
> I don't even run 60psi in my 700x35 cross tires on my touring bike.


Why not? You'll roll a lot faster. 
Dad worked in the tire business for 50 years. I've gone out on a ride and wondered what was going on, since it is such a drag. Are my breaks rubbing? Check and see that tires had leaked to 40psi. Not sure why some would think a tire with more pressure doesn't roll faster, with less resistance. I can very easily feel (not perceived) a huge difference in rolling resistance, with high pressure.

Chris.


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## trailville (Jul 24, 2006)

happydog500 said:


> Why not? You'll roll a lot faster.
> Dad worked in the tire business for 50 years. I've gone out on a ride and wondered what was going on, since it is such a drag. Are my breaks rubbing? Check and see that tires had leaked to 40psi. Not sure why some would think a tire with more pressure doesn't roll faster, with less resistance. I can very easily feel (not perceived) a huge difference in rolling resistance, with high pressure.


I believe there was some kind of a study recently that showed that rolling resistance relative to tire pressure changed once you left the flat smooth surfaces behind. But even without that, I simply prefer traction, control, and comfort over rolling resistance. I'd rather clear a technical section or make a really tough techy climb than roll fast on the easy sections. Everyone has their own preferences.


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## happydog500 (Sep 29, 2006)

I like to clear a technical section, and really though techy climbs with higher pressure. I'll mix it up and try a little lower pressure on one of the next trail rides. I gotta hurry because it's getting pretty cold around here now. 

Chris.


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## gvs_nz (Dec 13, 2009)

happydog500 said:


> Why not? You'll roll a lot faster.
> Dad worked in the tire business for 50 years. I've gone out on a ride and wondered what was going on, since it is such a drag. Are my breaks rubbing? Check and see that tires had leaked to 40psi. Not sure why some would think a tire with more pressure doesn't roll faster, with less resistance. I can very easily feel (not perceived) a huge difference in rolling resistance, with high pressure.
> 
> Chris.


 Here's some info for you to give you confidence to try a larger volume fast rolling tire at low pressure. Many have switched over and like it. Like plenty before you,it pays to read all of a thread not just the last posts.

http://www.schwalbe.co.uk/pdf/techinfo.pdf pages 14 to 16


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## happydog500 (Sep 29, 2006)

Thank you for the link. I love to read stuff like this. 

Chris.


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## bigbeck (Feb 15, 2004)

Don't know your weight but 60PSI may be right for a skinny 2.1 tire under a 300 pound rider.

You'll be amazed at what you can clean on a slow technical climb by using a fat (2.5) front tire at low pressure. It works even better on technical descents. A real confidence builder. Most people are amazed at the difference a fat low pressure front tire makes.

However, if most of your riding is smooth hardpack, then all that big tires do is slow you down.


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## Turveyd (Sep 30, 2007)

Love my HUGE Volume RQ2.4 so much, I've got a 3" Arrow Savage coming heavy but should gobble rock gardens which I need help with, like there not there on the rigid to


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## 918biker (Jan 23, 2011)

I run 35 psi front and rear for everything, and i have a 2.4 front and a 2.25 rear its good on the trail or street and i run with tubes


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## rmasse10 (Aug 21, 2010)

This is something that came up the other day when my buddy just bought his first Full Suspension bike (Trek Fuel EX5). We are here in the Tampa Area and I asked the Trek Rep to check the tire pressure out the door and adjust it for one of the locations we hit (Alafia State Park). He said he runs them at 40psi. I thought that was awfully high since I run my Stumpy FSR 29 at about 28 front and back, he thought that was awfully low. I weigh in about 240lbs and I feel pretty fast on the trail at that pressure although I may try a higher pressure just for the comparison. I havent gotten a flat since I moved the pressure above 25.


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## mr.niles (Feb 5, 2007)

*60 front/ 70 rear....*



trailville said:


> 60psi, Wow.
> I don't even run 60psi in my 700x35 cross tires on my touring bike.


on the pump track, 2.1 small block 8's, 165lb rider, hardtail.

trailville: saw your comment about this being a xc thread - when did this become strictly a xc thread?? xc can cover a broad range of riding on a broad range of terrain. that's what's been good about this thread, there's a lot of specific info here that may be helpful for what certain riders are looking for.

sometimes higher pressure works very, very well.


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## Turveyd (Sep 30, 2007)

1 rather major thing to remember here people :-


PRESSURE GUAGES DON'T WORK!!!

The 60 is likely really 40's area, and the 22's are likely 30's area.


Try a few marvel at how your mates give a totally different reading to your own.


Some tires, you need higher pressure to keep the knobs out to get traction, RK2.2's are like this, run them to soft and they become full on slicks and yes they'll role faster but there slicks nothing more.


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## trailville (Jul 24, 2006)

mr.niles said:


> trailville: saw your comment about this being a xc thread - when did this become strictly a xc thread??


When the OP posted it as "Tire pressure for all around XC riding" . But it's not like this would be the first thread to run a little off the initial topic.


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## mr.niles (Feb 5, 2007)

*yes, a good gage is necessary....*



Turveyd said:


> 1 rather major thing to remember here people :-
> 
> PRESSURE GUAGES DON'T WORK!!!
> 
> ...


never trust the gage on your pump - it is almost surely wrong. use it as a guideline to overinflate your tires before using a proper gage to bleed down to your target pressures. get an accurate gage from mcmaster-carr or a motorcycle shop, etc. the only problem with these gages is no chuck for presta valves. to get accurate pressures while using a good gage, i've had to convert all my tires to shrader. i don't recommend using those little brass presta-to-shrader converters.

my buddies like to use my gage when we ride together, because we all trust it.


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## ancient rascal (Mar 2, 2010)

How much sag should your high volume tire show under rider weight when using lower tire pressure? This seems pretty soft what I have here in these tires and shows some tire sag with my 155 lbs. When squeezing the tire is feels pretty soft. Running Forte Lunar light tubes. I don't have a decent tire guage.


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## PVR (Oct 29, 2006)

As others have said, get a tire gauge. Visual "sag" of the tires doesn't give you very much information IMHO as there is so much variability in sidewall stiffness amongst different tires. You need to experiment with tire pressures in different conditions to find out what works best for you.


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## xc-biker (Feb 3, 2011)

ancient rascal said:


> View attachment 615687
> How much sag should your high volume tire show under rider weight when using lower tire pressure? This seems pretty soft what I have here in these tires and shows some tire sag with my 155 lbs. When squeezing the tire is feels pretty soft. Running Forte Lunar light tubes. I don't have a decent tire guage.


Good question. From your picture, one cannot definitely identify substantial sag. You tire really feels pretty soft?
I tried the same with my bikes. The first has Mythos XC II and the second Fat Albert tires. To investigate the sag, I took pictures when sitting on my bike (i.e. sag) and when the bike unloaded (i.e. no sag). You can clearly see that there is sag under rider weight (165 lbs).
Note that the tire pressures were carefully adjusted by a mountainbike tire pressure specialist. He knows how to account for the individual aspects of the tires, the bike and its rider.


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## ancient rascal (Mar 2, 2010)

xc-biker said:


> Good question. From your picture, one cannot definitely identify substantial sag. You tire really feels pretty soft?
> I tried the same with my bikes. The first has Mythos XC II and the second Fat Albert tires. To investigate the sag, I took pictures when sitting on my bike (i.e. sag) and when the bike unloaded (i.e. no sag). You can clearly see that there is sag under rider weight (165 lbs).
> Note that the tire pressures were carefully adjusted by a mountainbike tire pressure specialist. He knows how to account for the individual aspects of the tires, the bike and its rider.


Prolly need to use a few methods to get it close. Hand squeeze. tire gauge. And just a thought. A sag gauge. Have a weight set up to enforce a sag on said wheel on a rigid floor. Have a means to measure the inside part of the rim to the floor measuring sag. Once you find your ideal tire pressure you can get back to it with the sag factor. Example floor to inside top of rim aprox 3 inches or whatever it is. Horseshoe type gauge over bottom of rim. Bet it gets it pretty close. :skep: It's OK to let me have it on this.....I can take it !


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## jonshonda (Apr 21, 2011)

While I am no racer, I do ride single track and am close to 300#. I prefer 30 psi in my Sepcialized Fastrack tires front and rear. Anything more and I can't find traction when I need it on climbs and roots.


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## TORQ (Apr 10, 2011)

I'm 190 pounds plus gear and I'm riding conti Xking 2.2 FR/RR on flow rims. Running 18psi (according to my pump) front and 23psi rear lately and am very happy. Not many large sharp edges to worry about in my local trails. I'd up the pressure a bit if riding rougher trails at speed but only as much as is necessary. The traction and control of "softer" tires is awsome! Really helps keep the bike planted.


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## ovlaicu (Apr 6, 2011)

I am runing Botrager XDX, tubeless. Run 18 front 20 rear, and it's ok for grip and bump absorbtion, no rim contact, but if you end up jack knifing the front you will pop the tire of the rim, or loose air presure.
25 front and 30 rear doesn't soak up the bumps as good (you feel more of the terrain) but the tire stays put


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## Rum Runner (Feb 13, 2008)

I've posted last year in this thread and was running 2.1 Nevs. Had a ton of flats last year. Running tubes.

This year I switched tires and am running a 1.95 Nev (150g lighter than 2.1) front and my Karma rear (under 400g which is around 280g lighter than the rear Nev 2.1 it replaced).
Pressure for several XC races has been 27 psi front and 29 psi rear with no flats(tubed) (knock on wood!!!)
Traction has been better than I anticipated with a couple of wet races and our local race at Camp Fortune is extremely gnarly, rocky and rough  
Doing an Ultimate XC race on 19th of June, 100 kms of crazy single track and 10,000 - 12,000 feet of climbing from what I read on this tire combo so will be a good test 

Cheers,
Paul


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## SGP495 (Jun 21, 2011)

::eekster::eekster::eekster:


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## Rum Runner (Feb 13, 2008)

So a quick report on the UltimateXC 100km race.
Managed to finish in 10 hr and 40 mins with one flat and one slight mechanical.
I was running the 1.95 Nev F @ 27 psi and 2.0 Karma R @ 29 psi.
Where I flatted several other riders flatted. It was a rough fast downhill section. 
99 % f the trails were dry or mildly moist. It consisted of soft loamy forest floor to rooty to gravel to Canadian shield solid rock. Were a couple short sections of maybe 50 feet of swamp black mud, bit clayish. 
I had super traction except the clay part and a few fast downhills with smallish type gravel.
There were a lot of STEEP sections and the tires had more traction than I had power left haha.
Two gravel climbs of 1 hr each of relentless no stop UP, no plateaus, of 8-25% section of 1600 ft and 1900 ft with 1-2 inch gravel. Was pretty loose stuff but still was gripping well with minimal slippage. Some of the downhill sections after those climbs were insane! ! ! Switchback after switchback hard on the both brakes feathering front brake to not go over bars ! ! 
In retrospect I am super happy with these tires in any type of dry conditions and non clay type mud. OK on wet roots from other rides.
So for me on my 4" FS GT @ 28ish lbs and me around 135 lbs the 27-29 psi worked really well. I rode just about every type of dry conditions... Sand, tall grass, Loamy forest, rooty forest, big/small gravel, rock, dirt .....
Was a section at finish as we zig zagged downhill through the village on pavement and cobblestones that I was just ripping through and the tires felt super solid with no feeling of the tire wanting to roll on the rim. I felt like I was rolling on the road bike !
Cheers,
Paul


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## kalpana1788 (Jul 9, 2011)

We try and take the hassle out of y


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## rmasse10 (Aug 21, 2010)

Ive kept mine at about 28 front and about 26 back....that seems to work fairly well for me right now. I run tubes and still no issues...but I have tried a gamut of pressures and noticed the higher pressures (at least for me and my trails) tended to slow me down...alot, and backing them off gave me more speed and maneuverability....so my recommendation is to try some variations out for yourself and see what you like


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## graciebarrabjj (May 1, 2011)

*Psi*

I just got back from a 3 hour ride. Conditions were stilla bit muddy with tons of damp rocks a wet roots....i run 35 psi in front on geax Saguaro 2.0 and 35 rear michelin gravel country 1.95....the runs were a bit slippery but still ok


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## ianz2 (Feb 16, 2009)

i run 52psi on 2.2's and i am 175 on short travel fully


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## Wanny (Jul 30, 2011)

45 psi... or I will start to flat too much. 210 lbs


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## Ofroad'bent (Jul 10, 2010)

*Schwalbe RR+ Stan's- Pressure Q for mixed riding*

After reading this thread, I switched out my tires for Schwalbe Racing Ralph 2.25 SS rear and 2.1 front, with Stan's on the rims. First time going tubeless.

I'm looking for tire pressure suggestions for overnight adventure racing with these.
We'll hit dirt roads, ATV trails with deep muck-holes, rocky Canadian Shield, unrideable swamps and decent doubletrack. Probably no twisty purpose-built singletrack.

I'm a light guy at 150lbs but my bike's got a lot of rear weight bias, and I'm carrying a lot of gear, much on a rear rack (Long story). I've raced this way for years, with 40PSI in a Hutch Python 2.25 on the rear and a Bonty Revolt-X 2.0 on the front with 30PS!.

I'd appreciate pressure suggestions for the new tubeless setup. I know harder tires would be better for the dirt roads, but I'd lose more time if I can't make it over the nasty bits or if I get flats.

Thanks in advance.


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## ricky916 (Jun 7, 2011)

Wanny said:


> 45 psi... or I will start to flat too much. 210 lbs


weird, im 220~ geared up and I run 33-35 front and rear and haven't pinched flatted yet, when I was at 29 and 30 I did all the time.


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## Abagaba (May 30, 2011)

I need two more posts so I can start a new thread in "Wheels and Tires", thats where this belongs.

Ever mount your tubeless tires and get a bit of a wobble because the tire is not perfectly aligned on the rim? 

How important is it for the tire to roll true?

I had a small wobble once on the rear tire but not bad and it held air just fine. I had a bike shop mount my last pair of tires when I purchsed new tires. One tire wobbled noticeably and hasn't held air very well. I will remount it but I was wondering if there are some tips for getting the tires true to the rims when mounting tubeless tires. BTW- Using Stans sealant, works great otherwise. ALSO, IT'S A SIDE TO SIDE WOBBLE.
The bike is a 2008 stumpy w/ Specialized Captain tires. Rims are Specialized brand and are true.


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## Abagaba (May 30, 2011)

Second post. Yea!


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## CrozCountry (Mar 18, 2011)

gvs_nz said:


> Here's some info for you to give you confidence to try a larger volume fast rolling tire at low pressure. Many have switched over and like it. Like plenty before you,it pays to read all of a thread not just the last posts.
> 
> http://www.schwalbe.co.uk/pdf/techinfo.pdf pages 14 to 16


Outstanding paper. For the lazy, here is a quick summary:


Schwalbe said:


> Off-road rolling resistance decreases significantly with increased tyre width. For instance on grass the wide mountain bike tyres required 15.41 W less rolling resistance power than their narrower equivalents.





Schwalbe said:


> Off-road a reduction of tyre pressure reduces rolling resistance. In a meadow for instance going back from 4.0 to 1.5 bar (57 to 21 psi) can save remarkable 18 Watts of power.





Schwalbe said:


> *FIRMLY inflated narrow tyres are history. 'Fat' and less air speed things up!*


On the road it's the opposite.

As for me, as low as the tire does not squirm. I can't get myself to slam the wheels into rocks to see how low you can go without a flat.


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## trailville (Jul 24, 2006)

*My pinch-flat-free streak is over.*



trailville said:


> To be honest, I've never had issues with pinch flatting. I think part of it is due to the the mainly rounded rocks we have around here (thanks glaciers), and part is due to the fact that I started mtn biking on rigid bikes and even though I run suspension now (front and full), I still unweight the bike as I go over and through stuff.


Well, I can't say this anymore. After 2 decades of riding without ever getting a pinch flat and having run pretty low psi for at least the last 5 or so years, it finally happened. I was heading out for a quick trail ride on my rigid SS this afternoon, and though I normally put 24-25 in a rear 2.1 tire, my gauge read 23.5 and I thought "that's fine". Well, immediately after hitting a crude rock bridge (basically a line of larger rocks across a shallow creak), I heard the air whoosh out and knew my luck had finally run out. To make things worse, since this was just intended to be a quick ride, I didn't bring a spare inner tube as I normally do, and, of course, my unopened tube of rubber cement in my patch kit was empty when I perfed the top (I've had that happen before with old patch kits). So I got to walk.


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## 1362 (Sep 12, 2010)

I have 2.2 mountain kings and when running28-30psi pinch flat almost every trail ride. my weight is 180. I started running 35psi and no pinch flats. So tailer the psi to trail and you.


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## Veda (Dec 17, 2009)

If there is such a thing as an exact science to tire pressure for offroad bike riding then we wouldn't be having these threads all over the net. I read somewhere that the proper pressure should be when the sag is 15%, then what about those tires that use softer compounds? Would the 40% front 60% rear times your body weight formula work in all applications? Is it faster to have a wide tire with low knobs ran at low press rather than the usual narrow high press? Are you really faster overall by having a tire that's fast and slippery rather than a heavier one that grips?

There's no right and wrong. It all depends on the particular trail you're riding, your riding style, and your body weight. I too had spent too much on tires experimenting different types. Sometimes sold them after 1 ride. Unlike in US, all of my tracks involve all kinds of conditions including mud. Now I just ran Nobby Nic Pace Stars 2.1 which has the awesome grip due to soft knobs yet lighter than anything else in the market. I just play with the PSI for the different conditions. Sure soft compounds wouldn't last that long and will cost more $ in the long run but I get both safety, comfort and speed in all conditions.


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## Veda (Dec 17, 2009)

mr.niles said:


> just fyi....i was involved in this thread a while ago. after plenty of riding various tire pressures on maxxis high roller 2.5 dh casing tires, i'm at 27 front and 35 rear on my dh bike. any lower and i flat.


Your point being that because of lower pressure you're slower not due to higher rolling resistance or difficulty pedaling but because of flats. But that should be out of the question if you're running tubeless which also means you can run even lower pressure. Go tubeless bro!


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## the old fool (Jan 27, 2008)

Interesting thread guys ... I have always run high pressures in my tire 'cause I'm a big guy who doesn't like to repair flats. I'm 105kg (231 lbs) and running a 2.5 Weirwolf up front and a 2.4 Motoraptor on the real of my old '95 Avalanche. I had 45 psi in them yesterday and I notice they were a little bouncy so I'll drop 'em to 35 psi and take my friends Mr tire pump and Mr accurate pressure gauge on my next ride.


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## CrozCountry (Mar 18, 2011)

the old fool said:


> Interesting thread guys ... I have always run high pressures in my tire 'cause I'm a big guy who doesn't like to repair flats. I'm 105kg (231 lbs) and running a 2.5 Weirwolf up front and a 2.4 Motoraptor on the real of my old '95 Avalanche. I had 45 psi in them yesterday and I notice they were a little bouncy so I'll drop 'em to 35 psi and take my friends Mr tire pump and Mr accurate pressure gauge on my next ride.


You do get more flats in low pressure, but you don't get flats running tubeless


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## the old fool (Jan 27, 2008)

Well if i have to go tubeless I might just have to get a new bike !


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## trailville (Jul 24, 2006)

the old fool said:


> Interesting thread guys ... I have always run high pressures in my tire 'cause I'm a big guy who doesn't like to repair flats. I'm 105kg (231 lbs) and running a 2.5 Weirwolf up front and a 2.4 Motoraptor on the real of my old '95 Avalanche. I had 45 psi in them yesterday and I notice they were a little bouncy so I'll drop 'em to 35 psi and take my friends Mr tire pump and Mr accurate pressure gauge on my next ride.


Wow, I'm surprised a 2.4 Moto would even fit on the back of a '95 Avalanche.


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## CrozCountry (Mar 18, 2011)

the old fool said:


> Well if i have to go tubeless I might just have to get a new bike !


It's not that bad. Stan's conversion kit works, its much cheaper than a new bike.


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## the old fool (Jan 27, 2008)

*low pressure is better*

I will have a look at Stan's thanks

I found 35 psi had an amazing effect on my ride, the bike rolled well stuck to the ground better and my hands didn't get such a beating

So I dropped the pressure to 30 psi and it's even better ...

Thanks for the advice :thumbsup:


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## mr.niles (Feb 5, 2007)

Veda said:


> Your point being that because of lower pressure you're slower not due to higher rolling resistance or difficulty pedaling but because of flats. But that should be out of the question if you're running tubeless which also means you can run even lower pressure. Go tubeless bro!


yes, doing tubeless this dh season. works very good, but can't lower the pressures much without hitting the rim - there's al;ways that one damn rock that's the perfect shape in the place where you really want to ride to bonk your rim on.


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## MtnMan1 (Aug 25, 2011)

mr.niles said:


> yes, doing tubeless this dh season. works very good, but can't lower the pressures much without hitting the rim - there's al;ways that one damn rock that's the perfect shape in the place where you really want to ride to bonk your rim on.


Yep. I run 32/34 on my 2bliss spec purgatory 2.4/2.2 tires. Always felt great, never had any flats. Until this weekend riding at Snowshoe; miss-timed a rock step-up and BAM had a rather explosive burp of the rear along with a heavy hit to the rim, shredding the rear tire. :madman:

Don't know what I could have done differently...other than having a wider wheelset to run DH tires, or a different bike, or being a better rider and not bashing into stuff. It's not like I was running super low pressure.


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## MtnMan1 (Aug 25, 2011)

mr.niles said:


> yes, doing tubeless this dh season. works very good, but can't lower the pressures much without hitting the rim - there's al;ways that one damn rock that's the perfect shape in the place where you really want to ride to bonk your rim on.


And because I'm thinking about getting a different set of tires for lift riding after this weekend, I'm curious as to what you went with. Rim width? tires? UST rims and tires? or conversion? and what pressure?


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## shiggy (Dec 19, 1998)

CrozCountry said:


> You do get more flats in low pressure, but you don't get flats running tubeless


Sometimes you get fewer flats because you have more control and can avoid the big pointy bits rather than sliding/bouncing into them.

And tubeless does not guaranty you will not flat.


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## gvs_nz (Dec 13, 2009)

CrozCountry said:


> Outstanding paper. For the lazy, here is a quick summary:
> 
> On the road it's the opposite.
> 
> As for me, as low as the tire does not squirm. I can't get myself to slam the wheels into rocks to see how low you can go without a flat.


Just note that they were testing wide tires at low pressure. If you run narrow tires at low pressure you may find they feel slower. Rolling resistance relates to the distortion of the casing. A narrower tire probably distorts excessively at low pressure negating any benefit from running at low pressure.


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## overmodulated (Mar 26, 2010)

40 front + rear on my Rockhopper 29 exp.


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## B1KER (Jul 19, 2006)

ricky916 said:


> weird, im 220~ geared up and I run 33-35 front and rear and haven't pinched flatted yet, when I was at 29 and 30 I did all the time.


I had a talk with a buddy on the trail over the weekend and I told him I always have been at like 45 just out of the fear of pinching and the thought that it would make it roll faster on the climbing. I'm ok with the tire supposedly bouncing off of stuff because at 225 (not counting the gear) My suspension is eating up that bounce. LOL I was curious to see if other riders over 200 do the same. I had another friend on a ride a few weeks ago tell me about that study where the tire rolled better at lower pressures. Now after seeing it again I think I'm going to start lowering my pressure to see what happens. Thanks!


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## frehgv (Dec 1, 2010)

I always thought it was the riders choice only if it's within the tyres guidelines not to low not too high! that's what i did anyway.


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## Delirious (Jun 12, 2011)

I'm using 20-25 psi on my 2.25 Rocket Ron's on a 29er. I probably weigh 140 lbs with my gear.


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## 0010 0110 (Sep 20, 2011)

im 230 lbs i run 36 in the front and 40~42 in the rear


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## Frogfuel7 (Nov 1, 2011)

Just want to know should I run tubeless? What are the pros when riding tubeless?


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## ncmountainbiker (Oct 24, 2011)

I'm glad I decided to check out this topic. I've always ran 32psi just because that was what someone had mentioned to me when I asked. I'm going to start playing around with it more to see how the ride is effected.
Thanks!


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## hazardousmtb (Sep 26, 2011)

i run 30f/35r and i weigh 195lbs 

all terrains in my area


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## fsrxc (Jan 31, 2004)

Frogfuel7 said:


> Just want to know should I run tubeless? What are the pros when riding tubeless?


There are plenty of other threads discussing that, this one is about pressure.


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## CrozCountry (Mar 18, 2011)

I overdid it. I had a front tire roll off the rim this weekend after a landing from a tiny jump with the front not completely straight. Just got a digital pressure gauge, and checked how much pressure I had (eyeball the front with fingers, close enough). 10-11PSI in the front, 15 in the rear. Not kidding. No more 15 PSI for me. I will miss the traction, but not miss the tire rolling off 

The tire pressure gauge is my new riding buddy.


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## Rum Runner (Feb 13, 2008)

Pulled the trigger on some tubeless near the end of the summer. Did a couple training rides and a few laps of a 24 hr solo attempt when rear suspension broke and we didn't have tools to extract a broken part.
I was running around 23 psi front and 25 psi rear on 2.2 Mountain Kings. Tires worked great. Was almost perfect conditions so roots and rocks were pretty dry. Traction was great and tires felt like they rolled really well.
I couldn't seal them up without sealant but I only put 1/3 scoop of Stans and still holding air after 3 months.
I was using similar pressures in my tubed 2,1 Nevs and about 5 psi more in tubed Karmas on my very rough/rocky local course(Camp Fortune QC). Got a lot of flats this year when racing but while out trail riding only one flat as our focus is more on lower speed technical climbs and descents.
Will update in the spring when I get a chance to do more MTB'ing. Currently in Cyclocross race mode and using road bike on the rollers.
For fun I am runnining about 32-34 psi on Scwalbe CX Pro 700x30C with tubes and no flats two seasons 

Cheers,
Paul


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## WMBigs (Jul 11, 2009)

I don't know how much air I let out when I get to the trail head, whatever feels right. I started to check it when I got home. Found out 18-22 front and 24-27 rear was pretty typical. Much less than the old 1.95x26" pressures. 
Fully rigid. 2.35x29 WTB tires with tubes, Velocity Blunts. 175lbs + weight of bike. 
Every once in while I will feel the front tire bottom on the rim. No pinch flats on front yet. Have had a couple on rear long after the ride has ended. 
Trail is hardpack with river rock. Lots of sharp broken shale rock with a few roots.


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## helgiberg (Nov 24, 2008)

Start with something like 37psi front and 40 rear.
If you don´t get a punkture let 2psi out next time, after a fiew rides of litting air out you will fint your soft spot...

My main advice is to ride with 2-4psi less in the front wheel.

Cheers,
Helgi Berg.


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## suprteck (Sep 27, 2009)

Im 130lbs and running Ritchey Z-max Evolutions 1.9 in the rear at 23psi and 2.1 in the front at 20psi. Running tubeless with Stans ZTR olympic rims.


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## Gary H (Dec 16, 2006)

I'm 198 pounds, ride mostly hardpack. Current tires are Karmas and I run 40 up front, and 45 in the rear. I'm a 53 year old trail rider and in no hurry. If your like me, don't worry about getting exactly 16.3 psi or whatever in your tires. Tire pressure is WAY over rated for the casual rider.


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## cormy (Sep 11, 2010)

I run 26 psi with tubeless and I'm 150lbs.


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## the_punk_guarda (Nov 19, 2010)

60psi atras y 55 adelante


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## Guest (Dec 31, 2011)

*Mtb pressure calculator*

It seems to be a nice pressure calculator: mtb.ubiqyou.com


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## trailville (Jul 24, 2006)

Poqitas said:


> It seems to be a nice pressure calculator: mtb.ubiqyou.com


No thanks. Getting riding tips from magazine articles is how I ended up running too much pressure for far too many years. It all sounds good when you're a noob, but once you start to actually know something about mountain biking, you quickly figure out the guys that write for those magazines don't know squat.


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## Joel RW (Nov 26, 2011)

171 pound rider, shimano xt UST rims, maxxis ardent exC/UST/LUST 26x2.25 tires on both ends, 20 psi front 22 psi rear. Any lower for me and I can feel a loss in performance. running tubeless.


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## Guest (Jan 5, 2012)

*...*

...


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## chantheman84 (Sep 20, 2011)

I had mine at 15psi before , me and my bike weighs 175lbs combine , but 25 psi seems to be the winning pressure for me on Geax mezcal 2.1 w/tubes, now i just went tubeless couple days ago w/ the same tires, so I'll probably have to go up on pressure a little.


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## CrozCountry (Mar 18, 2011)

My problem with going around 15PSI was tire rolling off the rim. I am in mid twenties now. The difference for the Nevegal is that I have to lean the bike more into the turn to get the side knobs to bite, not a biggy.


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## merc13000 (Dec 15, 2010)

I'm surprised at some of the high pressures people are running(40+ psi) for trail riding. I'm fairly new to the sport, but usually go about 35psi rear 33psi front on my hardtail and I've never had a pinch flat(knock on wood). I'd go a little lower in pressure but I am nervous of pinch flatting. I'm 205lbs and currently use 2.1" Weirwolf race tires.


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## LONO100 (Jan 10, 2012)

wow, so much discussion on tire pressure. being mostly a BMXER my whole life, ive always prefered to have my tires high pressured. i understand the benefits of aring down, i do a lot of 4-wheeling and airing down is key, but personally i hate any type of rolling resistance when im on my bike and i hate repairing flats. i get the increased traction of aired down tires and its benefits though. i did the shafter grade in bolinas twice this summer, and the second time i aired down the rear tire a bit to keep that back wheel biting up that crazy incline, but generally i like my tires to be right at 45-50 on my hardtail. call me crazy but im handling business out on the trail, so i guess it comes down to each rider experimenting and finding whats feels right for the type of rider they are.


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## PedroC (Aug 14, 2008)

Since buying a AM bike with 160mm suspension I have really been pushing the speed when going downhill to limits never reached before (to my experience at least) and therefore having a good tyre set up has become more important than ever for me as loosing grip at speed has already proven to be very painful. 

Traditionally, when riding my XC racer, I always had my tyres at 42psi because that is what Ned Overend said in his book he used for racing to avoid pinch flats, and as a big fan I followed the advice (yes, I am that old) totally ignoring any variations in between me and him (all geared up I weight 225lbs). Which wasn't a bad thing as 42psi for my weight is far softer than for his.

When I experimented with tubeless a couple of years ago I found out for the first time the benefits of lower pressure. It was great the amount of grip I was getting from 28psi in comparison to 42 without feeling increase on rolling resistance. I felt safer and faster.

At the moment I am using Contis Baron 2.3 with tubes at 30psi front and 35psi rear. I am getting an amazing performance on wet rocky ground and am yet to get a pinch flat.


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## matbar20 (Jan 30, 2012)

I'm 150 pounds, and ride a hardtail. 35-40 psi is perfect, things roll faster, and pinch flats almost never happen. If your skills are up to the decrease in traction, than its wll worth the extra pressure for low rolling resistance, and running less risk of fixing a flat tire (nothing slows you down more) Even with a tubless set up, ride at least 30 or more to avoid the bead rolling and breaking the seal.


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## mobius911 (Oct 25, 2011)

For those running tubeless this is Stan's recommended starting point: divide your weight by 7, then subtract one for front pressure, add 2 for rear. For me at 200 lbs that works out to 28 front and 31 rear. 

Note that this the recommended starting point and not a firm rule. I am running 23 front and 26 rear on Maxxis Ikon 2.2.


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## WMBigs (Jul 11, 2009)

I just checked my pressure. Did a ride today with the dogs so it was pretty slow paced. Pressures are read from Specialized floor pump with gauge. 
16psi front- felt a little low, bottomed the tire once but no flat. 
20 psi rear. 
WTB Exiwolf 2.35 on Velocity Blunts


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## CrozCountry (Mar 18, 2011)

mobius911 said:


> For those running tubeless this is Stan's recommended starting point: divide your weight by 7, then subtract one for front pressure, add 2 for rear. For me at 200 lbs that works out to 28 front and 31 rear.
> 
> Note that this the recommended starting point and not a firm rule. I am running 23 front and 26 rear on Maxxis Ikon 2.2.


That formula does not take into account tire width, which is a big factor. When I run the formula for me, I get very close pressures to what I use on 26"/2.4" tires. But on my XC bike that uses 1.9 tires, I use 10-15 PSI more.


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## opiejab (Mar 15, 2010)

*215 lbs male*

I run 35 in front with 2.3's and 40 in back with 2.1


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## zrodtx (May 9, 2010)

I usually run 20-25 PSI in my rear 2.0 tire. Tubeless 29er. Yesterday I bent the hell out of my Stan's Crest wheel going through an armored creek crossing at average speed. I was pretty shocked. At a 140 lb body weight I rarely have issues with wheels. I guess I'm going to start running 30 psi.


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## sparkyrides (Jan 19, 2012)

190lbs with all my gear. 28 psi in the front, 32 psi in the rear on 2.24's


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## spartacus (Aug 2, 2004)

175lbs and I run (pending trail and conditions) anywhere between 38 to 42. For the most part on faster trails the higher pressure and slower trail the lesser pressure.

Mud I let a little out, sticky trails higher and dry usually I use the feel factor (if the tire is not sticking I let a touch out till it feels good)

Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/


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## shiggy (Dec 19, 1998)

spartacus said:


> 175lbs and I run (pending trail and conditions) anywhere between 38 to 42. For the most part on faster trails the higher pressure and slower trail the lesser pressure.
> 
> Mud I let a little out, sticky trails higher and dry usually I use the feel factor (if the tire is not sticking I let a touch out till it feels good)
> 
> Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/


Basically, on a rough surface higher pressures bounce more. the tire/wheel moves up more than forward.

Lower pressure lets the tire conform to the terrain and maintain forward momentum.

Same reason suspension is faster than rigid on rough terrain.


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## spartacus (Aug 2, 2004)

Thank You. This makes sense
I keep hearing this from some of the people out by me and it perplexed me because there was no explanation. I think they Just conveyed info they herd with out understanding why.


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## skiwi (Mar 8, 2010)

shiggy said:


> Basically, on a rough surface higher pressures bounce more. the tire/wheel moves up more than forward.
> 
> Lower pressure lets the tire conform to the terrain and maintain forward momentum.
> 
> Same reason suspension is faster than rigid on rough terrain.


No, that is not the theory. The theory is that a wider tyre is faster than a narrower tyre for MTB use because the longer, thinner contact patch requires the tyre to "lift" more than a fat narrow one. Schwalbe did a study looking at this and concluded as above. Some of the benefit is small (around 10watts IIRC) but some was surprisingly large. Depending upon the type of terrain. Note that on hard surfaces, (i.e. road bike) the opposite is true.

WRT tyre pressure - as the decrease in pressure allows the above effect to occur, it will be faster, but at some point the extra drag of the bigger contact patch will have the opposite effect.

Remember that simple physics means that the actual size of the tyre has no effect on the contact patch size - it is only the air pressure in the tyre. In other words a 26x1 tyre running 30psi will have the same contact patch size as a 29x2.3 tyre @30psi. The shape will change (long and thin vs short and fat), but the size won't. Generally speaking the long thin contact patch (narrower tyre) will have advantages in traction and braking, whilst the short and fat contact patch (wider tyre) will have advantages in cornering.

This is why decreasing tyre pressure increases contact patch size which will improve traction due to the greater tyre surface area interaction with the terrain.


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## hoolie (Sep 17, 2010)

I am Mr 30 psi on both my Tubeless Ready Tire sets on both UST rimsets. Accidentally rode 25 psi tonight! I am now Mr 25 psi


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## beerrun (Jul 31, 2007)

I would add that pressures required depend on terrain. I did a 11 mile climb the other day on my steel rigid 8 speed, was great uphill with 40 rear 35 front. But then the washboard on the way down was crazy! I prob let out almost 20lbs on both wheels. Only way I could maintain control at speeds of 25-30mph. Had I had suspension with tubeless, I would have maintained the same pressures.


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## ZXFT (Oct 17, 2010)

spartacus said:


> Can someone explain the "lower pressure the tire rolls faster" theory to me.......I dont get it :-/


Studies show you're faster when you can stay connected to the trail. Larger contact patch=more traction=faster


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## Rum Runner (Feb 13, 2008)

ZXFT said:


> Studies show you're faster when you can stay connected to the trail. Larger contact patch=more traction=faster


Also I would imagine some tire deflection over smaller bumps uses less energy than a harder tire transmitting that energy through the frame, suspension and even rider...
just my two cents.....

Plus more traction as stated above...

My two cents .....

Cheers,
Paul


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## CrozCountry (Mar 18, 2011)

Rum Runner said:


> Also I would imagine some tire deflection over smaller bumps uses less energy than a harder tire transmitting that energy through the frame, suspension and even rider...
> just my two cents.....
> 
> Plus more traction as stated above...
> ...


Makes sense. When suspension moves most of the energy is lost in damping.


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## ZXFT (Oct 17, 2010)

Its kinda like the 29er argument: If it rolls smoother, it will be faster.


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## snowgage (Mar 14, 2012)

36 psi.. sounds pretty reasonable to me...


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## CrozCountry (Mar 18, 2011)

snowgage said:


> 36 psi.. sounds pretty reasonable to me...


Reasonable to who? Riding what?
It depends on tire width, terrain, rider weight, rim width, tube/tubeless among other things. Just for myself I run 22-40 PSI in different bikes (used on the same trails).


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## m3bas (Dec 24, 2011)

I weigh about 83kg and have been running 25 front/ 28 rear, Racing Ralph 2.25 tyres on loose/ rocky conditions. Managed to put a dent in my carbon Roval front rim on the weekend from hitting a rock so i'll be adding a few psi of pressure from now on. Bit less grip but better than destroying carbon rims.


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## Benjamin79 (Feb 17, 2012)

Great post with lots of input. I read all the posts and did as some suggested and took my bike and floor pump with gauge down to my little single track loop with one steep and rocky descent with a narrow bridge at the end. I started with pressure in the upper 30psi range in both tires and played around. I ended up with 25 for the front and 28 for the back and the increased handling was great and very noticeable in overall control and less "bouncing" when compared to the higher tire pressures.


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## danielsilva (Aug 13, 2011)

Prefer 25 psi on the front, 30 psi on the back.


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## FLMike (Sep 28, 2008)

im 170 lbs

On a previous bike with 2.4 Maxxis advantages, I preferred 28 psi front, 30 rear

I recently bought a Cannondale RZ 120 and went with 2.1 Kenda Nevegals. I prefer to be at 35 psi otherwise it feels way too squirmy in the corners. Although I find starting at 40 psi its noticeable too hard over roots.

all tubed tires


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## Bech (Mar 11, 2012)

3,5bar in Specialized Storm Control 26x2.0


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## Bech (Mar 11, 2012)

3 bar in racing ralph 26x2,25 

But i might be way off.


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## fsrxc (Jan 31, 2004)

Bech said:


> 3 bar in racing ralph 26x2,25
> 
> But i might be way off.


Does 1 bar = 15psi?


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## FLMike (Sep 28, 2008)

fsrxc said:


> Does 1 bar = 15psi?


1 bar = 14.5037738 pounds per square inch (no, i didnt know that off the top of my head. I used google)


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## Ilikemtb999 (Oct 8, 2010)

14.5psi equals 1 bar


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## Ilikemtb999 (Oct 8, 2010)

Some high pressures being run. I usually shoot for 28psi but I'll run 25psi if that's what it's leaked down too.


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## chantheman84 (Sep 20, 2011)

It really depends on the tires, trail conditions, and riding style, I can run from 18 to 30 front and 20 to 40 rear


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## dutchdoublea (Sep 23, 2009)

run 50 psi


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## MSU Alum (Aug 8, 2009)

I'm 59 yrs old, 165 lbs, medium fast on the descents in Park City Utah. Primarily interested in climbing speed. I had been running 28 PSI in front (on a Yeti 575 with a 150 mm front fork) on a WeirWolf LT 2.55 and 30 PSI on a 2.30 Tioga Psycho Genius on the back (on Stan's Crest rims, tubeless). More than a 2 PSI decrease causes the tires to begin to fold under while cornering. I have now placed Conti X-King, 2.4 RS front and back, tubeless, and find I still need to run 30 rear and 28 front to get the same resistance to the fold under while cornering. I'd run lower pressure were it not for the cornering issue because it makes climbing a dream.


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## vttix (Jan 16, 2012)

155lbs - I am running ADventage tubeless and I ran 40psi back and front this week.
I encountered some front wheel control issues on soft over hard, OK my lack of skills is probably the number one factor but my tire pressure may have been too high. I never had the same feelings when running 20-30 psi.


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## dirtdan (Jun 27, 2011)

I'm not racing (yet), but been riding since the 90's. I started out running tubes and 50 psi back then and now I run tubeless and in the range of 23-26. I'm 160 pounds and have ridden Continentals pretty much all of the time with my preference now with Trail Kings with a 2.2 in the back and a 2.4 in the front. I've been experimenting with the tubeless version vs. the non-tubeless version and it seems even in the rocky and rooty areas that I ride that the lighter, non tubeless versions holds up just fine.

After running tubes and high pressures and then no tubes and low pressure, I confidently feel there is no comparison between the two in terms of speed and confidence. I've also discovered that I can convert just about any rim to run tubeless with just stan's tape and a valve. One rim I had was stubborn and I had to add a layer of gorilla tape over the rim tape to get it to seal, but I think just about any crappy rim can be converted with the help of an air compressor.


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## fsrxc (Jan 31, 2004)

vttix said:


> 155lbs - I am running ADventage tubeless and I ran 40psi back and front this week.
> I encountered some front wheel control issues on soft over hard, OK my lack of skills is probably the number one factor but my tire pressure may have been too high. I never had the same feelings when running 20-30 psi.


Yes, 40psi in the front tire could be reducing traction and control.


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## mtblol (Feb 12, 2012)

25ish. I weigh 140.


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## wschruba (Apr 13, 2012)

Around 35 with 190 pounds on the bike. Much less and the tires squirm and squeal over obstacles.


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## bmwjnky (Mar 5, 2009)

I'm running 20psi front and 24psi rear with Specialized LK Control 2bliss tires in 2.0 width with Stans rim strips and a home brew sealant. I'm 160 pounds with an average riding style, no huge jumps or anything like that. I mainly ride on loose gravel/decomposed granite over concrete like hardpack.


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## MSU Alum (Aug 8, 2009)

Apparently, it also depends greatly on your pressure gauge. I finally got a good quality gauge. It's about 5 PSI lower than my floor pump and 4 PSI...in the other direction...from another tire gauge I have.


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## whooda (Nov 27, 2011)

why are you guys running such high pressures? What kind of terrain are you running?

I run 20ish up front and 25ish in the back. I ride sandy hard pack with roots and lots of pine straw and leaves. If I raise the pressure to 25 in the front it slides all over the place, the front washes out like crazy. If I leave it at 18 to 20 it rides great. I hit roots and large curb sized roots with no problem at all. I could not imagine running 30 or 40. 

I have a 2.2 ikon exo up front (or 2.4 ardent) depending on the weather and a crossmark 2.1 out back.


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## smokehouse4444 (Apr 24, 2011)

The tires that are "high pressure" tires, such as the Maxxis Ikon, what are you guys running in them. I'm about 230# and riding in hardpack/rocky/loose over hp, with 29 x 2.2 Ikons. Should I just run them at the normal (for me) 35ish psi? Or should they be run with higher pressure. What is the advantage of having a high pressure tire?


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## chantheman84 (Sep 20, 2011)

smokehouse4444 said:


> The tires that are "high pressure" tires, such as the Maxxis Ikon, what are you guys running in them. I'm about 230# and riding in hardpack/rocky/loose over hp, with 29 x 2.2 Ikons. Should I just run them at the normal (for me) 35ish psi? Or should they be run with higher pressure. What is the advantage of having a high pressure tire?


I would definitly do some testing, start at 35psi and work your way down to where you'll get the most amount of grip without dinging the rims and or rolling the tires under, during hard cornering. I own Ikons also and weigh 150lbs with a 25lbs bike full riding gear is 175lbs total, I run 25-28 psi in mine front, and alittle more in the rear like 30-35 to help decrease rolling resistance , ran tubeless. On the road rides on my mountain bike I jack em up to 40psi


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## ewejin72 (Sep 2, 2011)

I'm 185lbs, running 35psi F 38psi R on Maxxis crossmark 2.0 with Dt Swiss X1600 rims for a few weeks since converting to tubeless, so far so good......climb better and no more flats........will try to lower a couple psi this weekend....see how it handles.....


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## redd4573 (Apr 15, 2012)

Are you all racing or something. :???: I use too race and neve:crazy paid that close attention to PSI ever. All I have ever done was put in about 40 in remembering how hard or easy it was to sqeeze and go ride. Not that you can't notice a difference in a 3-4 psi change, but you would have to be tuned into your bike pretty well to notice it. Besides that if I were to run anything less than 30 psi I would get snakebit every time out. :crazy:


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## ZXFT (Oct 17, 2010)

redd4573 said:


> Not that you can't notice a difference in a 3-4 psi change, but you would have to be tuned into your bike pretty well to notice it.


IMO +/- 3-4 psi is a huge difference that doesnt require a 6th sense to detect.



redd4573 said:


> Besides that if I were to run anything less than 30 psi I would get snakebit every time out. :crazy:


Tubeless man... Its the way of the future.


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## cspartan (May 14, 2012)

Recommendations on pressure. Just got a '12 Dawes Haymaker 1200 17" with this setup

Rims WTB Speed Disc Double Wall Aluminum
Tires WTB Velociraptor Blackwall 26 x 2.10

Sidewall says 40-60 so I put them at 50. I am 135# and a total noob. I ride mostly well packed gravel trail with a few pretty clear dirt trails with minimal roots and rocks. 50 felt good, but my hands were numb after a 15 minute ride on these dirt trails. I know there could a lot of other factors to that but hoping for a bit more cush if I lower the tire pressure.


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## Ilikemtb999 (Oct 8, 2010)

At 135lbs I'd say you should be in the mid 20's psi wise. 50 is just crazy


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## jacksonj51 (Mar 30, 2012)

180lbs... run 24psi front & 27psi rear in just about all my tubeless set ups no matter the tire (mostly schwalbe's)


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## stumpy2 (May 20, 2012)

Tubeless. 33 psi rear and only 16 psi front in a 2.25" tire - I have a rigid fork so it's my only suspension. Never burped... yet :thumbsup:


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## redd4573 (Apr 15, 2012)

Great at this rate we will be talking nito and beadlocks soon Now lets use our heads a little better than we have been :madman:. Tire makers have invested alot of $$$ in R&D, I personally run Panaracer Dart and Smoke Tube combo :ihih:.I find they work for me. I run roughly 35-40 psi, I say roughly because I really only get as close as I need to be because most tire guages are very inaccurate anyways :shocked: get any three different ones and try it. That being said the side walls on my tires read recomended psi between 30-50 psi. Now I'm not cracking on anyone's veiw on this topic but I believe the tire makers are spot on. I have had little issues with traction outside of poor judgement in placement of said tires. If you look at a correctly inflated tire from the approching angle it revels a crown, if one were to lay the wheel and tire at say 15 - 20 degrees to the left or right the contact area remains the same. And with weight on the bike say all of my 200lbs :blush: I could find the tires rolling a bit and increasing this area.Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison but it's not to far off point. But the most important thing is we all have fun riding even if it seems goofy how others do things:ciappa:


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## BigwheelsRbest (Jun 12, 2007)

ah yes but if you were running tubeless with UST tires the bead sits tighter, then throw in no suspension and a nice fat tire and all you need is low pressure for less stress on the wrists.
OK so I wouldnt do it in my car but then I dont go 100 mph on my bike...


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## Ilikemtb999 (Oct 8, 2010)

redd4573 said:


> Great at this rate we will be talking nito and beadlocks soon Now lets use our heads a little better than we have been :madman:. Tire makers have invested alot of $$$ in R&D, I personally run Panaracer Dart and Smoke Tube combo :ihih:.I find they work for me. I run roughly 35-40 psi, I say roughly because I really only get as close as I need to be because most tire guages are very inaccurate anyways :shocked: get any three different ones and try it. That being said the side walls on my tires read recomended psi between 30-50 psi. Now I'm not cracking on anyone's veiw on this topic but I believe the tire makers are spot on. I have had little issues with traction outside of poor judgement in placement of said tires. If you look at a correctly inflated tire from the approching angle it revels a crown, if one were to lay the wheel and tire at say 15 - 20 degrees to the left or right the contact area remains the same. And with weight on the bike say all of my 200lbs :blush: I could find the tires rolling a bit and increasing this area.Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison but it's not to far off point. But the most important thing is we all have fun riding even if it seems goofy how others do things:ciappa:


You're also running tires developed like 20+ years ago and they're standard clinchers. Try running tubeless and you'll change your views. PS my tires have a MAX of 40 psi


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## Kratos (May 22, 2012)

My front tire is around 2,2bar, rear is 2,5bar. Good traction, I don't like high pressures at all.


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## redd4573 (Apr 15, 2012)

I have no need to ride tubless ut:. Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started:skep:.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up :thumbsup:


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## jacksonj51 (Mar 30, 2012)

No mounting issues, don't carry a spare, low tire pressure, takes 10 min to mount tubeless, no flats in over 2 years since going tubeless, and forgot what a tube even looks like. Loving the tubeless kool-aid.


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## FLMike (Sep 28, 2008)

redd4573 said:


> I have no need to ride tubless ut:. Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started:skep:.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up :thumbsup:


While I dont ride tubeless, im educated enough on the subject to realize youre completely out of touch with reality. Engaging in attempts to correct you, as another has already realized, is fruitless.

With a recent registration date and 13 posts, id suggest lurking and reading more and posting a tad less.


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## jacksonj51 (Mar 30, 2012)

Gonna go lurk and read how to install tubes and up my tire pressure in order to make my riding more enjoyable, thanks for the recommendation!

#FeelingsHurt


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## Ilikemtb999 (Oct 8, 2010)

jacksonj51 said:


> No mounting issues, don't carry a spare, low tire pressure, takes 10 min to mount tubeless, no flats in over 2 years since going tubeless, and forgot what a tube even looks like. Loving the tubeless kool-aid.


LOL this exactly. I run tubeless compatible rims and tires and it's super easy to use and has been dead nuts reliable.


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## trailville (Jul 24, 2006)

redd, 
I fully understand not wanting to get caught up on all the equipment hype, but as someone that spent many years exclusively with the Dart/Smoke combo (I ran them for over a decade) I strongly encourage you to try some new tires. There are much better tires available today.


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## redd4573 (Apr 15, 2012)

Wow you guys are easy. I've been riding for close to 20 yrs I have seen things come and go some great some not so much. I have tried many diferent types of tires and I do run a couple semi slicks later in the summer if trails stay dry more and soft spots firm up. Like I have stated before this is just my opion I supose we are all allowed to have one. For me mtbing is a way to relax and injoy life. See inside these last 20 yrs I've raced and trained my way into as I called it cycling slavery. Not to say that all that doesn't or can't make others happy but it's not for me and after slowing down I saw this sport as I did when I first started riding, SIMPLE. Just passing some zen like info on to others open to those who like a sound debate. If I upset anyone..... well sorry I was to busy riding and not lurking on a forum learning proper etiquette:ciappa: Hope to meet you all on the trail someday. Oh and I will not be hard to find I will be the slow guy you are passing with the retro tires on a hardtail with a smile on his face:thumbsup:.


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## skiwi (Mar 8, 2010)

redd4573 said:


> I have no need to ride tubless ut:. Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started:skep:.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up :thumbsup:


Tubeless is about physics. You run lower pressures. Benefits in traction and braking (=speed). And way less flats. I have had 1 flat in the last 4 years of running tubeless.

And I checked, the earth is not flat.


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## ZXFT (Oct 17, 2010)

redd4573 said:


> Wow you guys are easy. I've been riding for close to 20 yrs I have seen things come and go some great some not so much.


I know, tubeless is a fad, just like disc brakes and suspension forks.


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## stumpy2 (May 20, 2012)

redd4573 said:


> I have no need to ride tubless ut:. Seems to be several mounting issues with some products and others make no sense to me at all. Most people running tubless still carry a spare tube with them? They only developed tubless for the DH racing crowd which is understandable when running fast and balls out over things 90% of riders will never attempt. But the folks in marketing got an idea push it though the media and when the mags get an itch for advertisng $$$'s they say they like the Kool Aid because it reduces wieght on thier 29ers and the mad dash for the NEXT cool thing had started:skep:.Oh well I'll just keep mounting my trusted 20 yr old tires and tubes ( which takes about 10 mins to do) and injoy my way of riding while others are spending their hard earned $$$'s on this unneeded technology that the Kool Aid machine keeps serving up :thumbsup:


If you live where we do you need to run tubeless otherwise you'd go crazy - at least one puncture every ride. It's the hoarthorn and blackthorn and bloody whoknowswhatthorn but they get in your tubes mate...

And in any case ghetto tubeless doesn't generate much profit for anyone, and loses the tube makers some.


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## wahday (Mar 23, 2012)

I don’t have a gauge, so I don’t really know what I run my tires at (and gauges are notoriously inconsistent anyway – well, consistent with themselves but not from one gauge to another). I just do it by feel. Generally I use the squirrely cornering rule. If I am feeling that, I inflate what I guess is probably 2-3 psi and see how it feels. I’m running new tires now (2.4 in front and 2.35 in back, up from 2.1s) so I’m still playing with getting the right feel. But generally, I like it as low as it can go before I start to feel that cornering squiggle. I’m riding all rigid (and loving it!) so I value the extra give. It’s a better feeling, too, to be running lower. Like I am more inside the terrain than just on top.


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## Ilikemtb999 (Oct 8, 2010)

wahday said:


> I don't have a gauge, so I don't really know what I run my tires at (and gauges are notoriously inconsistent anyway - well, consistent with themselves but not from one gauge to another). I just do it by feel. Generally I use the squirrely cornering rule. If I am feeling that, I inflate what I guess is probably 2-3 psi and see how it feels. I'm running new tires now (2.4 in front and 2.35 in back, up from 2.1s) so I'm still playing with getting the right feel. But generally, I like it as low as it can go before I start to feel that cornering squiggle. I'm riding all rigid (and loving it!) so I value the extra give. It's a better feeling, too, to be running lower. Like I am more inside the terrain than just on top.


Because if there's anything more accurate than a numerical gauge it's the human touch.......


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## Lovrix (May 14, 2012)

I run my Nobby Nic's 2.1 on 2.3bar with latex tubes. They are very soft compared to Smart Sam and Albert.


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## wahday (Mar 23, 2012)

Ilikebmx999 said:


> Because if there's anything more accurate than a numerical gauge it's the human touch.......


Touche! :thumbsup:

My point was simply that just because Jimmy's gauge reads 25psi, it won't necessarily be the same as 25psi on your gauge. So don't take other peoples' numbers too seriously - make your own adjustments for what feels best. Use your own gauge if you want (and always use the same one), but as far as seeking a "standard" pressure, that's going to be hard to nail down with so much variability (in gauges, tires, riders, etc.)

The truth is I'm too lazy and cheap to go get a gauge, so I ride and make adjustments for what feels best. And while the ladies say I have a magical touch, you're right, I'm not a human pressure gauge...


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## stumpy2 (May 20, 2012)

Got wrapped up in all the hype and bought a decent (expensive) digital pressure guage. Can't believe what I'm reading on it (and riding on)!

Also riding rigid, so I value a soft fat tire up front, but I measured the pressure last night (after reading these posts) and it was 13 psi :eekster:

Can that be right? It feels soft, but I don't get the squiggly corners yet. It feels just right - a bit of suspension and really good grip. It is a Nobby Nic 2.25" snakeskin running tubeless...

(Rear is different - that's at 33 psi which feels like it's right)


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## Rum Runner (Feb 13, 2008)

I got a new tubeless wheel set in the fall and have now had some rides and a race on them and I can say I am definitely having a positive experience running UST tubeless rims and tires.
Running Mountain King 2.2's and really liking them. 
I had to add just the smallest amount of Stans to seal around the valve stem and totally seal off the bead. Probably 1/2 oz in each tire. They held air all winter hanging in the garage and so far seem to be holding air well. 
I started out around 25 psi and each ride dropped a little and this past weekend and the first race 2 days ago I ran approx 18-19 psi F/R (GT i-drive FS, 145lbs rider)
I have been able to clear tough sections better than most so this means I have pretty good traction due to the variety of tires the other guys are riding on. I won't go lower than this and maybe up a pound or 2 for race days as our course is rough rocky and rooty. 
At the local races last year I only finished 3-7 races due to multiple flats. This first race I didn't hold back, other than building up some confidence, over the 3 laps and no flats ! I did look down a few times though.

Cheers,
Paul


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## bandit1 (Jun 27, 2011)

redd4573 said:


> Me myself and I believe that none of us would go out and deflate our motorcycle or car tires 10 -15 percent to GAIN traction??? I understand that this is not a great comparison


Actually you are not far off, and YES, I WILL GO AND DEFLATE MY VEHICLE TIRES TO GAIN TRACTION!!! Every time I take my Jeep off road or when I need the extra traction here in the great NorthEast in the snowy season, I will deflate my tires just to gain that extra traction.

That said, I fully understand the low psi and the benifits of it. I myself do not run lower psi on my MTB because I have not had the need to YET. When I find myself riding trails more regularly that require me to do so, I will.

As far as to say whats better, tubes or tubeless, it depends on what you need for where you ride.

So how low is too low? Well thats up to you to decide for yourself. I could ask a few questions on the subject, but seeing as this whole thing is a hotly debated subject to begin with, I will leave my questions out for now. A lot of what I wanted to ask about has already be said, so I will leave it at that.

As to the arguement about "riding for 20 years," does not make you an expert. I have been riding since I was 5yrs old, that means I have been riding for the last 28 years, am I am expert, absolutly not. Will I pretend to be something I am not, heck no. Anyone who has lived and paid the slightest bit of attention has seen fads come and go.

That all said, did I say you lied, NO, did I hurt someones feelings by what I said, ehh maybe, it happens, its life.

Bottom line: It doesnt really matter unless you are happy and enjoying your setup on your bike. There are a ton of variables that go into YOUR setup of YOUR bike. Yes it is good to seek opinion in order to educate ones self, but it is bad when you belittle the opinion becasue it is not like your own.


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## redd4573 (Apr 15, 2012)

Did the voices come backut: I never claimed to be a expert. Just trying to have a good discusion and a gain and understand of others opinons. How does stating MY opinon belittle others? But then agin I'm not an expert on THOSE sort of things:smilewinkgrin:


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## allanknabe (Oct 7, 2008)

I rode at the weekend with 40 psi in my Continental Rubber Queens (2.2). The downhill was terrible, I'll be looking to come down to around 30 psi.


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## bandit1 (Jun 27, 2011)

redd4573 said:


> Did the voices come backut: I never claimed to be a expert. Just trying to have a good discusion and a gain and understand of others opinons. How does stating MY opinon belittle others? But then agin I'm not an expert on THOSE sort of things:smilewinkgrin:


I say it like I see it, I did not say that YOUR particular post/opinion quoted was in question, but after reading a few pages of replies and seeing posts that were negative in nature because one persons opinion differed from theirs, I felt the need to say it.

I have seen it before where people think that because they have been doing something for XX years that they are gods gift to (fill in the blank). It is typically these people that are almost always wrong and give bad advice. Your post was the last one read by myself, so it was the one used as an example. If I was calling you out directly, I would have typed your screen name in directly. The only thing I said that was in your direction *redd4573* was the very first paragraph about airing down just to gain traction.

Everything else I had to say was a general statement put out there and not directed towards anyone in particular. nothing more, nothing less.


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## skiwi (Mar 8, 2010)

I don't think anyone can seriously debate the benefits on traction of deflating a tyre. After all the size of the tyre (width, height, diameter) is irrelevant in determining the size of the contact patch - the only relevant factors are the total weight and the PSI in the tyres. Simple physics. Put another way, a 26er running a 1" wide tyre will have the same contact patch size as a equivalent weight 29er running a 3" wide tyre, provided that they are running the same PSI. Different shape, but same total size.

SO I can double my contact patch size by running 20psi when I used to run 40psi. Benefits are in better traction, braking and cornering. That is until the negative effects of tyre movement rob the bike of the control necessary to handle comfortably. Or I puncture too often. Or both.

So, it is better to adopt the approach of achieving the minimum pressure to produce the results you are looking for, than the other way around.


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## Ilikemtb999 (Oct 8, 2010)

skiwi said:


> I don't think anyone can seriously debate the benefits on traction of deflating a tyre. After all the size of the tyre (width, height, diameter) is irrelevant in determining the size of the contact patch - the only relevant factors are the total weight and the PSI in the tyres. Simple physics. Put another way, a 26er running a 1" wide tyre will have the same contact patch size as a equivalent weight 29er running a 3" wide tyre, provided that they are running the same PSI. Different shape, but same total size.
> 
> SO I can double my contact patch size by running 20psi when I used to run 40psi. Benefits are in better traction, braking and cornering. That is until the negative effects of tyre movement rob the bike of the control necessary to handle comfortably. Or I puncture too often. Or both.
> 
> So, it is better to adopt the approach of achieving the minimum pressure to produce the results you are looking for, than the other way around.


..........uhhhh


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## RC-Archer (May 5, 2012)

I use TLAR* ie my thumb.


*that looks about right.


I usually adjust the tire pressure to the conditions of the trail.


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## skiwi (Mar 8, 2010)

Ilikebmx999 said:


> ..........uhhhh


Like I said - simple physics. And most people into cars & bikes don't get it. Like you I take it....


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## Ilikemtb999 (Oct 8, 2010)

skiwi said:


> Like I said - simple physics. And most people into cars & bikes don't get it. Like you I take it....


So let's say a 200 lb rider sitting on a bike with a 1" wide tire at 20psi and a 200 lb rider sitting on a bike with a 3" wide tire at 20 psi will have the exact same contact patch?


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## skiwi (Mar 8, 2010)

Ilikebmx999 said:


> So let's say a 200 lb rider sitting on a bike with a 1" wide tire at 20psi and a 200 lb rider sitting on a bike with a 3" wide tire at 20 psi will have the exact same contact patch?


No, they will have the exact same size contact patch. The shape will be different.


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## Ilikemtb999 (Oct 8, 2010)

skiwi said:


> No, they will have the exact same size contact patch. The shape will be different.


How is contact patch and size of contact patch not the same thing?

The amount of tire touching the ground will be exactly the same is what you're saying then?


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## skiwi (Mar 8, 2010)

Ilikebmx999 said:


> How is contact patch and size of contact patch not the same thing?
> 
> The amount of tire touching the ground will be exactly the same is what you're saying then?


Contact patch size and shape are different things.

PSI is pounds per sq inch.That is the only thing holding up the weight of the bike/rider (less some sidewall stiffness).

So, in your example, 200lbs/20psi = 10sq inches. That is your total contact patch size (5 sq inches per tyre). For both the 3" wide tyre and the 1" wide tyre.

Contact patch size stays the same, but shape doesn't. As your tyre goes wider (at the same pressure), the contact patch shortens and widens. Hence you are trading off traction & braking for cornering.


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## Ilikemtb999 (Oct 8, 2010)

You brought up shape not me. I'm specifically talking about the amount of tire touching the ground.


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## skiwi (Mar 8, 2010)

It will be the same. Same total area. Different shape.


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## Ilikemtb999 (Oct 8, 2010)

I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.


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## skiwi (Mar 8, 2010)

Ilikebmx999 said:


> I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.


BTW, this is no "theory". It is simple fact. It applies to Tarmac and Dirt equally (albeit with different trade offs). If you don't believe it works this way, wander down to your local 4wd club and try and convince them about your understanding of the physics ;-)

Good luck with that.


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## CrozCountry (Mar 18, 2011)

Ilikebmx999 said:


> I ride exclusively in dirt. I'm going to go ahead and say your theory doesn't apply.


Its not "his theory", its basic physics. The contact area will be more or less the same, maybe the wider tire will have a few more knobs on the side touching the ground at lower pressure, making the patch a tad larger, but not significantly larger.
If we take a completely smooth tire with a thin carcass (like a road bike) then the area will be almost identical for the same pressure.


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## bandit1 (Jun 27, 2011)

so what your are telling me is that my contact patch will be the same as everyone elses at 20 psi even though I am 300lbs and someone else is 150lbs? I understand that it might not be a significant change in the size or shape of the patch, but I would have to disagree that the contact patch will be exactly the same regardless of bike and rider weight with different size/width tires.

If you have a 1 inch wide tire and a 3 inch wide tire both at 20 psi, the 3 inch wide tire is gonna have a larger contact patch on the same bike with the same rider.

I know it is considered apples and oranges here, but I have to make the comparison. This would be like you saying that the contact patch of a vehicle tire but on the same truck is exactly the same regardless of its width. A 12.5 inch wide vehicle tire has a larger patch over the same tire in a skinnier width.


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## joqpub4 (Apr 23, 2012)

At the risk of being flamed, i didn't read the whole thread... no that's not what he is saying. For a 300lb load at the same psi your total contact patch area is the same whether it is a 1" or 3" wide tire.

300lb/20 psi = 15 Sq. In

Now, if you only have a 150lb rider at the same pressure, your contact area is reduced...
150lb/20psi = 7.5 sq. in.

Having said that, in all honesty, you may not be running the same pressure to generate the same 'feeling' for the rider (after all tire 'squish does act as the 1st bit of suspension)... but that's what they were trying to state.


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## skiwi (Mar 8, 2010)

bandit1 said:


> so what your are telling me is that my contact patch will be the same as everyone elses at 20 psi even though I am 300lbs and someone else is 150lbs? I understand that it might not be a significant change in the size or shape of the patch, but I would have to disagree that the contact patch will be exactly the same regardless of bike and rider weight with different size/width tires.
> 
> If you have a 1 inch wide tire and a 3 inch wide tire both at 20 psi, the 3 inch wide tire is gonna have a larger contact patch on the same bike with the same rider.
> 
> I know it is considered apples and oranges here, but I have to make the comparison. This would be like you saying that the contact patch of a vehicle tire but on the same truck is exactly the same regardless of its width. A 12.5 inch wide vehicle tire has a larger patch over the same tire in a skinnier width.


No, If you are 300ilbs and another person is 150lbs then the different weights would mean different contact patch sizes, if you are running the same PSI. If you have 2 people the same weight, and running the same PSI, then the contact patch size wold be the same - regardless of the size of the tyre.


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## skiwi (Mar 8, 2010)

joqpub4 said:


> At the risk of being flamed, i didn't read the whole thread... no that's not what he is saying. For a 300lb load at the same psi your total contact patch area is the same whether it is a 1" or 3" wide tire.
> 
> 300lb/20 psi = 15 Sq. In
> 
> ...


Exactly. It's an important concept to get across in the debate about how to get the best performance out of your bike.


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## bandit1 (Jun 27, 2011)

After reading an article on the subject, I think I understand the whole concept better... I will share an excert of the article I just read about this subject.



> Tire Width. There is a view that a 20 mm width tire is faster than a 23 by virtue of its smaller cross section and lighter weight. Interestingly enough, this is not true. The people making the Torelli tires had noticed that the pro teams that they sponsored asked for 23s because they felt they were faster. When they investigated and did the testing, they found that the riders were correct. Let me explain.
> 
> Let's assume a 200 pound rider and bike unit. Let's also assume that the weight is distributed half over each wheel. That means that each wheel is supporting 100 pounds. Now, with a pressure of 100 pounds per square inch, the contact patch is one square inch. This is true no matter how fat the tire.
> 
> ...


Here for the full article

There is also this one but it refers to motor vehicle tires.


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## skiwi (Mar 8, 2010)

bandit1 said:


> After reading an article on the subject, I think I understand the whole concept better... I will share an excert of the article I just read about this subject.


Good summary and entirely correct. Interestingly, there is similar evidence (albeit from Schwalbe) of the same effect in MTB i.e. wider is faster.


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## bandit1 (Jun 27, 2011)

yea there are some articles that get into it deep talking about what happens at the leading edge of the contact patch with rolling resistance and the rubber fibers bending and what not. Made my head hurt reading it.


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## skiwi (Mar 8, 2010)

bandit1 said:


> yea there are some articles that get into it deep talking about what happens at the leading edge of the contact patch with rolling resistance and the rubber fibers bending and what not. Made my head hurt reading it.


I used to care about it as I tried to get my 26er race bike faster. Definitely proved it to my own satisfaction. However since migrating to a 29er, the dynamics are entirely different, and I've forgotten all about it. The 29er is plenty fast without obsessing about contact patch shapes...


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## AllMountain4Me (Jun 21, 2012)

Tire pressure varies for each tire. Tubed or tubeless? Front or back? You can go lower w/out tubes, and see improved performance. Experiment. I like 2-3 lbs. less up front than in rear. I also like a completely different tire for each (front and rear), since I believe they are responsible for two totally different things. Weight also impacts tire pressure, as does conditions and what you expect from your tires.

I like tubeless, and I find my sweet spot on my tires tends to be in the mid 20's. Your tires may be entirely different.


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## Fiendbear (May 8, 2009)

140lb rider, 23lb FS bike, Norcal XC riding including some technical... 

Front: 20 psi, Nobby Nic 26x2.25 EVO Snakeskin
Rear: 23 psi, Racing Ralph 26x2.25 EVO Snakeskin

I run both tires tubed and have not come close to pinching. I can get away with really low psi as I am light and these tires can be run at ridiculously low pressures. Fantastic grip for dry summer conditions and the extra volume provides some nice cush. Front tire just rails and the rear tire tracks nicely, but still kicks out when needed.


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## Josh_SL2 (Mar 30, 2012)

255lbs on 2.1s running 30/30. I've run as low as 24/24 after forgetting to check pressure before a ride and felt the rim on a rock or two but no flats.


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## raducanmihai (Mar 30, 2009)

I used to be a 200 lbs XC rider on a hardtail and my pressure was 42 front/45 rear PSI. Now I weigh 170 lbs and I also changed my wheels to XT M785 (UST rim). I run tubeless front (RocketRon 2.25 Evo TLR) and tube-type rear (RocketRon 2.25 Evo TLR). The rear was also mounted tubeless but I cut it ,so I had to use a tube.Since my new wheelset and weight loss I droped the pressure to about 33f/35r. I would like to try really low pressures to see how it feels,but the instructions on the Shimano site says the pressure should be between 29 and 58 PSI. 
I read here about pressures as low as 18 PSI (front) and 22 (back). Would this kind of numbers void my wheel warranty or,at least,increase the risk of rim damage?

PS: I will soon change the tires (or at least the damaged one) to WTB Bronson 2.1 TCS (mounted tubeless with Stan's) if this makes any difference.


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## roaringboy (Aug 26, 2009)

Problem i have is my regular ride features about 10 miles of road/paved tracks each way to and from the offroad stuff. Obviously you want higher pressures for the road and lower for offroad. I tend to try and find a happy medium which is about 30 front and 30-35 rear. 

If i'm driving to a trail i'll go 25-30 front and rear.

Riding a 2.0 front and a 1.9 rear (both tubeless).


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## 29 bike (Aug 2, 2012)

180 lb rider 23 pound niner 23 psi 2.4 RR front 28psi RR rear tubeless


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## ColinL (Feb 9, 2012)

the physics on tire contact patch is close enough, but technically doesn't conform exactly to the air pressure calculations, especially on wide rims or when using very stiff, heavy tires like UST.

the reason is very simple: more than just air is actually bearing the bicycle & rider weight. it's the tire carcass.

the carcass bears little weight using a 1.8" race-day-only semislick, but it bears a lot when you run a heavy tire on a p35. think about a runflat tire for a car. how does it bear the weight of the car with little to no air pressure?

anyway, just food for thought. this is another one of the ways people run ultra-low pressure is by using a wide rim and a beefy tire.


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## Barker (Apr 17, 2012)

I am 185# rider and went with the 40# tire pressure and when I was about 8 miles from my truck when I got a pinch on both tires and bent my rear rim. I was on a down hill run with lots of rock. The week be for I was on smooth dirt and more of a flat trail and it worked great. so i think a lot has to do with your riding terrain.


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## dhmoore (Aug 12, 2012)

The other day, I had a long ride on the paved road with some pretty steep climbs before getting off-road, so I had the tires inflated to about 40#, thinking that this pressure would be low enough to handle sandy surfaces... I quickly realized as I left the pavement and hit a 15% grade, with hard dirt and a thick coat of sand, that I really wanted to have less pressure in the rear tire - it spun out and slipped very badly - but I didn't want to let the air out because I didn't have a lot of time before dark and I had a long ride back on the pavement.

I've been thinking about getting a compressed-air cartridge-type tire inflator, but I'm not sure which one, and whether there are inflators that you can re-fill... I have DEFINITELY noticed widely varying performance with different tire pressures... Can somebody recommend the best way to quickly inflate/deflate and manage tire pressures while on the trail?


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## ColinL (Feb 9, 2012)

it can feel 'funny' when riding on pavement with trail pressure, like you have a flat tire, but it's barely slower if you actually measure your speed and elapsed time. you will lose a lot more time getting off the bike to mess with the air pressure.

I would get a high volume frame pump if you really insist on doing this.


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## ply5013 (Aug 15, 2011)

Can't believe I just read this whole thread...

...but I didn't read much about bent or dented rims. Are most of you able to go this low without worrying about your rims? I'm constantly thinking about them getting damaged.


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## geeter (Jun 21, 2006)

mr.niles said:


> in fact i do have timing device coming in the mail! yeah, it's hard to tell! that's why it's confusing to me. i'm always changing my presuures around to try and figure out what is best. i will try lower pressures, but i'm just not sure where to start. any ideas?


I can't remember where I read it, but recently I saw a formula for a base tire pressure from which you can adjust, depending upon your tires, trail type, conditions, etc. The formula was to divide your weight with helmet, shoes and backpack by 7. Subtract 1 lb for the front tire and add 2 lbs for the back tire.


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## CrozCountry (Mar 18, 2011)

dhmoore said:


> I've been thinking about getting a compressed-air cartridge-type tire inflator, but I'm not sure which one, and whether there are inflators that you can re-fill... I have DEFINITELY noticed widely varying performance with different tire pressures... Can somebody recommend the best way to quickly inflate/deflate and manage tire pressures while on the trail?


When I need to I carry a mini pump (like 150 grams) and a digital gauge (50 grams). Especially with a new bike/tires combo that I want to play with. Little weight, gives you insurance, reliable. When I ride with buddies one pump in the group is usually enough.


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## dhmoore (Aug 12, 2012)

Sounds H


geeter said:


> I can't remember where I read it, but recently I saw a formula for a base tire pressure from which you can adjust, depending upon your tires, trail type, conditions, etc. The formula was to divide your weight with helmet, shoes and backpack by 7. Subtract 1 lb for the front tire and add 2 lbs for the back tire.


Hey, that sounds interesting.... I'd like to see this tire-pressure formula. I've been using the caveman method: grab tire and squeeze hard, if going uphill, it okay if very squishy... if going downhill, no want so squishy, especially if have innertubes... if no steep up and downs, make tire hard like rock so bike pedal easier.


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## motoxc (Aug 7, 2012)

To all those who are resisting going tubeless as I was for years. I even had tubeless ready wheels and ran tubes, GO TUBELESS and don't look back.
No More pinch flats. I weight 195 and like to ride technical trails with as much rocks, ruts, roots and jumps as I can find. With tubes I ran 34/36 psi with an occasional pinch flat, tubeless I now run 26/29 on 2.3/2.2 tires with no issues. I have run as low as 21/25 but I feel the sidewall flex too much. As far as trail repairs, carry a spare tube and co2 cartridges with a quality inflator. I also carry a small pressure gauge to check pressure and a small pump just incase.

Best advice I was give regarding mountain biking was to go tubeless.


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## raducanmihai (Mar 30, 2009)

dhmoore said:


> Sounds H
> 
> Hey, that sounds interesting.... I'd like to see this tire-pressure formula.


It is on Stan's NoTubes site.


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## ColinL (Feb 9, 2012)

That formula is linear and as such I doubt it will work well for light and very heavy riders. A 115 pound woman can ride 15F/17R psi, really?


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## ZXFT (Oct 17, 2010)

raducanmihai said:


> It is on Stan's NoTubes site.


Damn, you beat me to it.

In my experience, its been closer to (weight/7)+3 in front, and (weight/7)+7 in rear, but I'm also suspicious of the readings on my floor pump. Its 10 years old and I have not found 35 psi from others peoples' pumps to feel like 35 psi from my pump. I end up running 31 f/35 r. Your experiences may vary



ColinL said:


> That formula is linear and as such I doubt it will work well for light and very heavy riders. A 115 pound woman can ride 15F/17R psi, really?


I'm a 200 lbs Cat 1 SS mtbr, so I think my tires have their work cut out for them :thumbsup:.


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## ghettocop (Jul 26, 2011)

Here is a cool app by Geax.....Bead seat diameter, tire type, type of riding, rider weight, etc....will calculate the lowest pressures you can run.

iTire Pressure « Geax.com


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## dhmoore (Aug 12, 2012)

Thanks raducanmihai n ZXFT... kewl stuff! :]

Holy COW, ghettocop! Dude! That's a VERY kewl app!

I was goofing with my pressures on a steep, rocky, ascent the other day and lowered the pressure waaaaaay down so the rims were bumping the rocks (tubless)... SERIOUS improvement in traction and much, much smoother climb... I knew lower pressure was better for climbing, and run low pressure, but not this low - like fifteen pounds! haha  did it just to see how low I could go... then put a few more pounds in and climbed some more... then again, and let some out... got it just right, but didn't have a pressGuage with me to record the exact pressure... on the descent I pumped 'em back up again several pounds more for the extra impact and stability at higher speeds... gotta get a guage... as I was riding, I was thinking "yea, one of these days we'll probably have a guage and a controller on the handlebars with a pressure adjustment while riding" wouldn't THAT be kewl!


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## Tillers_Rule (Sep 11, 2004)

Historically:

50F/50R
35F/45R

Now I'm at 35F/40R. I've found anything less in the rear and the tire distorts too much, I can go a bit less in the front but this combo seems ideal for me for now. I'm 215 loaded up. Picking up a new bike here, a 29", so I'll get to play with PSI again!


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## ZXFT (Oct 17, 2010)

ZXFT said:


> In my experience, its been closer to (weight/7)+3 in front, and (weight/7)+7 in rear, but I'm also suspicious of the readings on my floor pump. Its 10 years old and I have not found 35 psi from others peoples' pumps to feel like 35 psi from my pump. I end up running 31 f/35 r. Your experiences may vary


Quick update, I tried 29f/32r with a new floor pump (since my old one broke :sad and it felt very similar to my previous 31/34. I'll keep messing with pressure and see if I cant get it down to the stans formula.


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## CrozCountry (Mar 18, 2011)

ZXFT said:


> Quick update, I tried 29f/32r with a new floor pump (since my old one broke :sad and it felt very similar to my previous 31/34. I'll keep messing with pressure and see if I cant get it down to the stans formula.


2 PSI is well in the margin of error of floor pump gauges. Mine pump gauge has 5PSI difference than the other gauges which I believe are more accurate (one mechanical and one digital, both reading within 0.5SPI of each other)


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## Criswell (Aug 19, 2012)

So after skimming through this entire thread my head is spinning. I came on here looking for info because during trail riding my rear tire is spinning on steep climbs and the bike is bouncing around too much on descents. Obviously the psi im running is too high. 

Just for clarification...as the tire pressure drops what are you gaining and losing? Does a lower pressure provide more traction/braking or are you going to corner better?

This thread has been very informative. Thanks!


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## ZXFT (Oct 17, 2010)

Criswell said:


> Does a lower pressure provide more traction/braking or are you going to corner better?


Both. Assuming its not so low that your tire squirms in corners.


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## Simplemind (Jul 17, 2006)

ghettocop said:


> Here is a cool app by Geax.....Bead seat diameter, tire type, type of riding, rider weight, etc....will calculate the lowest pressures you can run.
> iTire Pressure « Geax.com


Muchas Gracias! Great app.(I like no brainer concrete answers, even if it's slightly off :thumbsup!


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## fsrxc (Jan 31, 2004)

Criswell said:


> So after skimming through this entire thread my head is spinning. I came on here looking for info because during trail riding my rear tire is spinning on steep climbs and the bike is bouncing around too much on descents. Obviously the psi im running is too high.
> 
> Just for clarification...as the tire pressure drops what are you gaining and losing? Does a lower pressure provide more traction/braking or are you going to corner better?
> 
> This thread has been very informative. Thanks!


Keep in mind rear suspension setup matters too.


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## CrozCountry (Mar 18, 2011)

Generally, with lower pressure:

Gain traction (cornering, braking, climbing)
Bike is little more vague
Bike rides more plush (less bounce, especially on a hard tail)
Less rolling resistance on rough terrain
More rolling resistance of flat terrain
More prone to pinch flats (tubes)
More prone to rim damage
More prone to burping and tire rolling off the rim (tubeless)

I think thats about it?


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## ddelport (Aug 20, 2012)

I am a 190-200 pounder excluding the 20 pounds of equipment, water and stuff on me and run 1.6bar soft front and 2 (very stiff) back tubeless onloose sharp rocky track. I need advise on the sort of tyres though since I have shredded two back tyres in the last two months - the last was a Scwalbe Rocket Ron EVO 26" and besides 7 pinky sized holes I fixed an inner and then after some 50K's popped went the sidewall - was this just bad advise from my shop since i run the same in front with no problem in the past year+? I now switched to Continental Speedking 2.2 which apparantly has thicker sidewalls. So far ok besides one small puncture that sealed up quick and Stans leaking small bits all the time from the valve and rim edge. Did not loose much pressure on yesterdays 50K run. I must add that the rim took a knock and bent when I hit a rock but it is almost 98% good but for a small wobble. Should I rather convert my backwheel to downhill rims, hub and tyres? Or will this be SO much heavier?


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## BIGABIGD (Jul 24, 2012)

This is a great thread... Except it looks like I wasted $80 on my new set of Geax barro race 2.0s. This is a low volume tire and I weigh 252 or so. I suspect a few of you will tell me to ditch them.

They're actually very good tires, and def better than my Nanos on the dirt. I've only ridden them twice on the trail tho, and the both rides were muddy - after the rain rides so they've not been fully tested yet. I'm running 28/30 right now, and don't think I should go much lower as I am a big MF-er.

My question is - would it be a good setup to go with a 2.3 tire in the front and leave the Geax in the rear? I'm not gonna put one of the Nanos back on as it's already been proven that they suck on the loose stuff.


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## ewise (Nov 8, 2010)

Throwing my experience into the mix. 
I weigh about 160-165# in full gear. I am running 2.25 Nobby Nic front and 2.25 Racing Ralph on back. Both are the TL-Ready, SnakeSkin version. I have put two scoops of Stans in each. They just work. I am running these on 26" XTR Trail wheels.

I have been riding these tires at between 19-22# F and 20-23# R and did the BC Bike Race at this tire pressure. They were a little soft/squishy on the roads but they just worked. 

I also ride fairly hard on a wide variety of terrain (steeps, rocks, smooth, sandy) with no problems (burps, air loss). That said, I am also fairly good at line selection and we don't have much in the way of sharp exposed rocks in Whitehorse.

The bead locks onto the rim and it's a bugger to break when I have to replace the Stan's (just did). It literally glues into place.


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## CrozCountry (Mar 18, 2011)

ewise said:


> The bead locks onto the rim and it's a bugger to break when I have to replace the Stan's (just did). It literally glues into place.


What I do is lay the wheel flat on the ground, and step on the tire close to the rim. With all your body weight on it the tire will separate from the rim, so far it worked every time and super easy. Once it separates in one point a tire lever can do the rest, and if not, step again on the trouble spot.


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## mr_z (Sep 12, 2012)

my weight is 225lbs i ride a '09 specialized rockhopper expert im new to riding what pressure is recommended for me? im new to all this mountain biking by the way.


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## CrozCountry (Mar 18, 2011)

mr_z said:


> my weight is 225lbs i ride a '09 specialized rockhopper expert im new to riding what pressure is recommended for me? im new to all this mountain biking by the way.


What tires? Size is a major factor.


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## mr_z (Sep 12, 2012)

26 x 2.00" specialized fast trak.


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## SpyderPride (Jul 22, 2008)

mr_z said:


> 26 x 2.00" specialized fast trak.


Try 30 front, 35 rear. If it feels squirmy (you'll know it when you feel it) or you pinch flat, bump it up 3-5 psi on the tire that is giving you issues until the problem goes away. I am nearly your weight with similar width tires, albeit a different tread style, and that's what I would do.

Sent from my ADR6410LVW using Tapatalk 2


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## TH-X15 (Aug 30, 2012)

geeter said:


> I can't remember where I read it, but recently I saw a formula for a base tire pressure from which you can adjust, depending upon your tires, trail type, conditions, etc. The formula was to divide your weight with helmet, shoes and backpack by 7. Subtract 1 lb for the front tire and add 2 lbs for the back tire.


That was helpful. Thanks.


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## moldau94 (Aug 16, 2009)

I weigh 180 fully loaded with 3L of water in my Camelback. Running Hans Dampf 26x2.35 in front at 24 psi and Racing Ralph 2.25 in the back at 26 psi.


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## georgeg23 (Oct 4, 2012)

I probably weigh 180 lbs loaded up. Still learning about tires. Limits are sliding off roots on a turn due to too high a pressure, 40 lbs or so. Let out air until a finger squeeze dents the side of the tire. Before I went tubeless rims, just converted-tubeless, it was like gaining a gear, rolling friction much better. Squirm on corners is creepy after a couple of gulp flats throw you down. Switched to foldable tubeless on tubeless-clincher rims, a much stiffer tire without squirms or gulps, gaining back some tire friction. Feels solid.

Bought a tire gauge and decided to run rated minimum of 30 lbs, but tire like a rock slipping on every flat stone and root. Started letting air out to gain secure grip on rocks and roots. Now they look slightly flatter and fatter on the bottom, squeeze test ok. Maybe if I think about it ahead of time I'll pump up on the electric pump at home to cut down on rolling resistance on the long miles, and then when I reach the trail, or large rocks on the road, I'll let out air when I unlock the front shock (w/hardtail), tuning pressure it down until it feels secure. I sure don't want a gulp flat, but those new clinchers really lock in, and I've had no flats, squirms or gulps since I went legit.

Of course, I've been really cautious about getting too low and have pumped up on the trail when it feels too soft. The last thing I want to do is go down on a gulp in a tight turn (have done) the bruises, road rash and near death experiences are not part of the fun. Part of getting older is slowing down knowing you're not as invulnerable as your glands lead you to believe. Having your life flash before your eyes is not for me now, or later.

I would like a lower pressure gauge as nothing over 40 lbs is of interest to me, and my 160 lb AccuGauge is not very useful in tuning lower pressures. Got any suggestions? I'll trade you a nice gauge for something easier to read at low pressures.


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## Schroedinger (Nov 16, 2005)

After 20 years of riding tires from 45-65 psi, I finally read this thread. I'm 6'0, 195 lbs with gear. Just got done riding my Spesh Epic 29er EVO with 30psi front and back... life changing. Tearing through rock gardens like a fat kid chasing an ice cream cone. No bottoming or pinch flats. 

Can't wait to try even lower pressure.


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## ZXFT (Oct 17, 2010)

Schroedinger said:


> After 20 years of riding tires from 45-65 psi, I finally read this thread. I'm 6'0, 195 lbs with gear. Just got done riding my Spesh Epic 29er EVO with 30psi front and back... life changing. Tearing through rock gardens like a fat kid chasing an ice cream cone. No bottoming or pinch flats.
> 
> Can't wait to try even lower pressure.


People like you are rare. Most people if they've been doing it one way for 20 years thats the "right way" to do it. Good job on having an open mind.


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## stumpynerd (Oct 8, 2012)

I weigh 200 lbs (not including camel back stuffed with tools & water) and run 32 psi front and back on my stumpy fsr. I have never had issues with flats or pinch flats, I tried 30 & 28 on a variety of tires and they felt too squirmy for my weight along with pinch flats.


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## SpyderPride (Jul 22, 2008)

stumpynerd said:


> I weigh 200 lbs (not including camel back stuffed with tools & water) and run 32 psi front and back on my stumpy fsr. I have never had issues with flats or pinch flats, I tried 30 & 28 on a variety of tires and they felt too squirmy for my weight along with pinch flats.


What tires are you using and how wide are they?

I am currently 215 without gear, running a 2.4 X-King front at 28 psi and a 2.2 Race King rear at 30 psi. I have narrow rims (17 inside) but would like to go lower as I haven't felt any squirm cornering, but the issue is that the tires tend to slide in the rim and tear off valve stems. This is currently remedied with gorilla taped beads but I don't want to push it. Oh how I wish I would have bought wider rims...

--
Sent from my DROID Incredible 4G LTE using Tapatalk 2


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## stumpynerd (Oct 8, 2012)

Im running 2.2 captains currently with American Classic MTB rims, Im not sure how wide they are but 32 psi works best for me on a wide variety of terrain.


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## bikeface.killa (Oct 16, 2012)

I usually ride the rear tire around 20psi. I'm 145 and ride technical single track with a lot of baby heads. I am riding tubeless 2.0 on 29er rims. Up front I run about 23 on 2.2s


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## davez26 (Dec 2, 2004)

Schroedinger said:


> After 20 years of riding tires from 45-65 psi, I finally read this thread. I'm 6'0, 195 lbs with gear. Just got done riding my Spesh Epic 29er EVO with 30psi front and back... life changing. Tearing through rock gardens like a fat kid chasing an ice cream cone. No bottoming or pinch flats.
> 
> Can't wait to try even lower pressure.


Yeah, sounds stupid, but I've gotten this old and I am just now toying with pressures on both the Road and MTB, and the results are eye opening.
I am so old school I still run the Smoke/Dart combo. I am feeling good at 25F/30R and it's been awesome. I may go a little less, just to see. I am going by the rule, 'keep reducing until you snake bite, then add 5'
We will see.

Sent via psychic suggestion....on Tapatalk.


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## BDozer (Mar 25, 2012)

I weight about 185lbs load up, bike is a 26lbs FS. Currently running 35/35psi ft/rr on Specialized Specialized "Fast Trak" Armadillo 2Bliss ready 26x2.00 ft and Specialized "The Captain" Armadillo 2Bliss ready 26x2.00. Both currently with tubes with sealant. I hate flats. 

Plan is this winter to change to something wider (2.25-2.4) and go tubless. Also will buy an accurate pressure gage. Then I'll experiment with which pressure is the best compromise for the range of surfaces I run on (pavement to lose rock/dirt climbs).


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## Ferrari353 (Oct 17, 2012)

I have 2.1" tires (I think--It says 26x2.1 on my tires (I'm kinda new to MTBing)) and I weigh 125 lb, so what kind of PSI should I use (or how low could I go)? On the tires it says the min PSI is 40 and the max is 65. I do XC mostly.
Thanks!
Also, everyone is saying "keep lowering it until you get pinch flats" but isn't that at all bad for the tire and/or tube to keep puncturing holes in it/them?


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## gmcttr (Oct 7, 2006)

Ferrari353 said:


> ...Also, everyone is saying "keep lowering it until you get pinch flats" but isn't that at all bad for the tire and/or tube to keep puncturing holes in it/them?


You may ruin a tube but probably won't hurt the tire while figuring it out (you're not going to be pinch flatting every ride over and over). At only 125# I'd start with ~32psi and go from there.


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## CrozCountry (Mar 18, 2011)

Ferrari353 said:


> Also, everyone is saying "keep lowering it until you get pinch flats" but isn't that at all bad for the tire and/or tube to keep puncturing holes in it/them?


I wouldn't say lower until you get pinch flats. There are many other reasons to stop lowering. In my terrain the tires will start to squirm in turns and feel like you are riding on gello before they flat. In a tubeless setup they can also roll off the rim in low pressure. Not to mention flat spotting your rim or getting too many dings and scratches. All are reasons not to go too low.

But for your original question, after a pinch flat the tube can be toast, because the cuts can be long. Tires seem to care less.


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## Ferrari353 (Oct 17, 2012)

gmcttr said:


> You may ruin a tube but probably won't hurt the tire while figuring it out (you're not going to be pinch flatting every ride over and over). At only 125# I'd start with ~32psi and go from there.


That seems like you'd be wasting a lot of patches fixing the pinch flats. I'll try 32 and see how it rides. If it doesn't feel right (or like jello), then I'll raise the PSI.
Thanks for the advice guys!


CrozCountry said:


> I wouldn't say lower until you get pinch flats. There are many other reasons to stop lowering. In my terrain the tires will start to squirm in turns and feel like you are riding on gello before they flat. In a tubeless setup they can also roll off the rim in low pressure. Not to mention flat spotting your rim or getting too many dings and scratches. All are reasons not to go too low.
> 
> But for your original question, after a pinch flat the tube can be toast, because the cuts can be long. Tires seem to care less.


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## sidewinder (Jun 15, 2006)

Here's the rule of thumb I've always used. I've never had a accurate gauges on any of my pumps, so I take the tire and "bounce" my weight down on it with the narrow outside of my palm. I should just barely be able to feel the rim when I bottom out on the front wheel. A tiny bit more pressure than that for the back.

This is for a rigid bike with 2.4" tires, tubes, and rhino lite rims.


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## jochribs (Nov 12, 2009)

I am running 29x2.3 Renegades on Crest rims at 15 psi front and rear with tubes, on a HT. I weigh 155. No problems yet, and they don't feel squirmy. When I first got these tires I aired them to 20 psi (which is what I was running my 29x1.95 Renegades at) and they were way too bouncy. Next tried 17 psi which was a bit better, but not quite what I was hoping for. 15 psi pretty much hit the spot. My home trails are relatively rocky, however I have been riding them for years and I am a somewhat smooth rider.

I'd like to get a separate gauge to confirm these pressures since I would not have guessed that I'd be running them and I am pretty surprised.


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## BigwheelsRbest (Jun 12, 2007)

What I have noticed is that the wider the tire, the lower the pressure I can get away with.

This leads me to another question - what is the widest tire people are running on Crest rims? I am currently on Nobby Nic 2.25" (at 17 psi) and want to go wider, but don't want problems with squirming...


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## jochribs (Nov 12, 2009)

BigwheelsRbest said:


> What I have noticed is that the wider the tire, the lower the pressure I can get away with.
> 
> This leads me to another question - what is the widest tire people are running on Crest rims? I am currently on Nobby Nic 2.25" (at 17 psi) and want to go wider, but don't want problems with squirming...


I think that the Crests are fine with that. I'm pretty sure I came across a Notubes forum question where the Notubes guy said the Crests could definitely handle a 2.3. I'll see if I can find it.

Crests are 21 inner width, so they're in my opinion and experience pretty suited at running wider tires.

I had been running 26x2.4 X-king's on my Bontrager RXL's which are the standard 19mm width, and to me, they always felt fine. I also ran those with tubes. They were the first generation Racesports and sealing them up was a PITA so I just gave up and used tubes. Blew my mind how well they rode and how low I could go with the pressure (around 20-21) and changed my mind about running skinnier tires.

I recently bought some of the X-king's in 29x2.2 in the RTR Protection version. Unpackaged one, put it on an aired it up, and it was way small...smaller than the Renegades at 1.95. Returned 'em. Hoping Conti actually starts delivering that tire in 2.4,


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## daniel harvey (Jul 23, 2007)

*rigid/hardtail/full sus variable?*

~200#'s geared up. I've been running Stan's Flow rims and Panaracer Rampages 2.35's, front and rear, on a rigid steel SS and a Yelli Screamy hardtail.

As many posters before, I go as low as I can on Pac. NW trails without rim striking or feeling too squirrelly. The low pressure obviously helps with traction, and also with the cush of the ride. I think I'm usually at 18-23 front and 20-25 rear. If I have to ride pavement for a long stretch, I'll inflate.

Here is my question. I do not think it has been addressed directly yet.
How does tire inflation and suspension, specifically FS, interface?

After a season of only having my rigid and HT I have just built a 650 SC Blur XC and am therefore thinking about this.

Does it make sense to run a bit higher psi with a FS bike, in order to better engage the suspension?
I imagine that there is an optimal psi where the cush in the tire works in concert with the suspension--where they are balance in the same way we need to balance front and rear suspension in a bike.

When I had a full suss before (a Rip9) I ran the tires as low as I did on my rigid and HT, but I always wondered about the tire psi/FS relationship.

Anyone have an opinion?


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## ColinL (Feb 9, 2012)

You would run the FS bike at the same pressures for a given tire as the HT bike, like you said. I see a lot of people running huge tires on rigid bikes to get max air volume tires to run them as low pressure as possible, in order to get a better ride. But that's of course nothing like full suspension.

You may not need higher pressure in a fast-rolling tire on pavement or gravel roads. I have not noticed any real difference between my trail pressure, 25F/27R, and running 5 psi more for the road. This is on a fast tire, a Geax Saguaro 2.2F/2.0R. On other tires, especially slow rolling tires, the difference was more significant.


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## shiggy (Dec 19, 1998)

daniel harvey said:


> ~200#'s geared up. I've been running Stan's Flow rims and Panaracer Rampages 2.35's, front and rear, on a rigid steel SS and a Yelli Screamy hardtail.
> 
> As many posters before, I go as low as I can on Pac. NW trails without rim striking or feeling too squirrelly. The low pressure obviously helps with traction, and also with the cush of the ride. I think I'm usually at 18-23 front and 20-25 rear. If I have to ride pavement for a long stretch, I'll inflate.
> 
> ...


Tire pressure is part of the setup with suspension, hardtail or fully. I have needed to change tire pressures for suspension bikes compared to what I used on a rigid bike. Change the suspension settings and have found I needed to adjust the tires again. How I changed the pressure varied with the specific tire and the suspension type. With some other tires it does not seem to matter what type of bike they are on.

I have also used tires that worked terribly on a rigid bike no matter the pressure. Moved them to a suspension bike and they were brilliant.

All goes back to the basic answer for this thread: you need to experiment and see what works best for you, your terrain, setup and riding style.


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## CrozCountry (Mar 18, 2011)

daniel harvey said:


> Does it make sense to run a bit higher psi with a FS bike, in order to better engage the suspension?
> I imagine that there is an optimal psi where the cush in the tire works in concert with the suspension--where they are balance in the same way we need to balance front and rear suspension in a bike.


I run a few more PSI on the hardtail rear tire to reduce the chance of pinch flats (comparing to equivalent tire on FS).


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## JoeJITSU (Jan 18, 2013)

So I just recently came from a ride here in Las Vegas and this trail has rocks pretty much everywhere. I decided to go tubeless and I think the pressure was at 40-45 on front and back. I am running Nevegal Crossfires 26x2.1 on the back. I got a "burp" riding on the ridge of a boulder, So I go and pump it back up not having a gage I just went by feel. About 2 miles later, I hit a pretty good rock and that was that. I go into my pack and look at my tube, Oh my god...Tube I bought had the wrong valve, I thought I bought a presta valve. My wife who rode with me was pretty pissed, We were 5 miles in , in the middle of the desert, Thank god there was a person that passed me off a 29er tube and I put in on my 26er and rode back safely.
Now I think it had a lot to do with me being 220lbs. I will stick to tubes till I lose about 25-30 more lbs.


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## borbntm (May 4, 2011)

JoeJITSU said:


> So I just recently came from a ride here in Las Vegas and this trail has rocks pretty much everywhere. I decided to go tubeless and I think the pressure was at 40-45 on front and back. I am running Nevegal Crossfires 26x2.1 on the back. I got a "burp" riding on the ridge of a boulder, So I go and pump it back up not having a gage I just went by feel. About 2 miles later, I hit a pretty good rock and that was that. I go into my pack and look at my tube, Oh my god...Tube I bought had the wrong valve, I thought I bought a presta valve. My wife who rode with me was pretty pissed, We were 5 miles in , in the middle of the desert, Thank god there was a person that passed me off a 29er tube and I put in on my 26er and rode back safely.
> Now I think it had a lot to do with me being 220lbs. I will stick to tubes till I lose about 25-30 more lbs.


I am right at 215lbs, run Stan's Arch wheel set, sealant and Nobby Nic tires running between 20 and 30 psi with no issues, it may just be the combo of wheel / tire causing your issue?

I have also heard of tires blowing off with psi to high, 40 could be to high with your combo, try a lower tire pressure??

It would suck for me to have to go back to tubes! Good luck....


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## Gregon2wheels (Jan 17, 2013)

I've read a couple of pages of this thread, but not all of them.

My new bike is tubeless from the LBS. I went from 35 to 30 psi. Tonight I tried 25 psi. Wow! I could hold tight corners that I used to slide on. I could also keep traction if I ran towards the edges of the trail and accidentally hit duff. *So my question: is there any risk of burping tires and having a major blowout if I run lower pressures?*

I'm running Ground Control 2Bliss 2.1s (stock on Speci Carve 29er HT). I weigh probably 190# with all my gear and the bike weighs 26#. Trails are not particularly technical -- mostly slightly damp hardpack with many roots and some mud (not deeper than the tire). On a scale of 1 to 5, 5 being the most technical, I'd rate them a 2.


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## Scott In MD (Sep 28, 2008)

Lower. And lower.


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## CrozCountry (Mar 18, 2011)

Gregon2wheels said:


> Tonight I tried 25 psi. Wow! I could hold tight corners that I used to slide on. I could also keep traction if I ran towards the edges of the trail and accidentally hit duff. *So my question: is there any risk of burping tires and having a major blowout if I run lower pressures?*
> 
> I'm running Ground Control 2Bliss 2.1s (stock on Speci Carve 29er HT). I weigh probably 190# with all my gear and the bike weighs 26#. Trails are not particularly technical -- mostly slightly damp hardpack with many roots and some mud (not deeper than the tire). On a scale of 1 to 5, 5 being the most technical, I'd rate them a 2.


Yes there is risk. I rolled a tubeless tire completely off the rim on a bad landing when the front was not straight. There is also a compromise in handling in lower pressure. Looks like you are around your sweet spot. I wouldn't go much lower than that, and always carry a spare tube with you in case it happens. It really depends on the trails and your riding style. Rocks and roots increase the chance of a burp, jumps, drops and high speed turns as well.
I now run around that pressure and I weigh little less and use fatter tires, after I put a couple of nice dings in the rims.


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## malariavalley (Jun 20, 2004)

MTB tech


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## rocksolid (Oct 12, 2010)

Great link,could exsplain why i had a front tire blow.


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## solidass (Jan 20, 2013)

I'm back on this "lower pressure" approach after discovering it on my own way back when. This is a good discussion for validation!

The odd thing I've found in recent years was that many bike shops, tire manufacturers, tire reps, floor pump instructions, etc. recommend the higher pressures -- the range of 35psi to 60psi depending on rider weight! It had made me think that my "lower pressure" approach was amateurish with no scientific basis for a better ride. That it was just psychological.

Designers of tire tread, I was once told, do not design them for 20psi riding. Not even for 25psi. This is why, I was told, the sidewalls are stamped with the range of something like 35psi to 65psi. And these are 2.1 29" knobby!


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## solidass (Jan 20, 2013)

malariavalley said:


> MTB tech


It recommends 30psi front and 33psi rear for me.


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## NordieBoy (Sep 26, 2004)

I'm still searching for optimal pressures on my MTB. On my cyclocrosser on the same tracks, I run 45f/70r on 33mm Maxxis Razes. Racing, that goes down to 40f/60r.
Those pressures were come across after using Sheldon Brown's tyre pressure page for a baseline. 15% drop when loaded and then tune for the conditions. Which would indicate about 30f/35r for 88kg on 2” tyres as a start point.


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## Bemiller (Jun 25, 2013)

After having read through all 15 pages of this thread my head is spinning. I am new to mountain biking and am currently doing single-track, technical uphill/downhill through the rocky woods of CT.

I have a Cannondale Moto2 at 35.5 lbs and my weight w/ gear is almost 160 so full weight on tires is 195.5 lbs.

I am riding (tubes) Kujo DH 26x2.35" rear and Specialized Clutch SX 26x2.5" in front. I have been riding w/ 30-32psi in both tires but it seems, from what I have read, that I should be lower. I will definitely be adjusting my tires for tomorrow's ride but just would like a ballpark suggestion from some experts here.


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## NordieBoy (Sep 26, 2004)

I'd go 3-4psi lower both ends and work from there.

I'm not fast at all and weigh 180 odd plus gear and am running 28f/30r on 2.0” tyres.


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## MSU Alum (Aug 8, 2009)

Time your rides. Sometimes a ride can "feel" fast, but time out slow. I've done this to adjust pressures and it works well over the long term. I have also found that different tires may work better at different pressures even though they are the same size. For example, a UST and "Racesport" version of the same tire at the same size work best at different pressures.


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## TonyB. (Jul 27, 2009)

Just go by feel. Ride what makes you feel confident, provided you're not burping tires or pinch-flatting. I did it this way and in the end found that my pressures were exactly what the calculator recommended for me.

Bonucing off of rocks and roots? Lower the psi.
Squishy feel, pinch flats or the tire coming off the rim? Raise the psi.


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## go-pirates (May 8, 2006)

Geax Seguaro 2.2's, 29". 24 psi, front and rear. 210 lbs. Works for me, with no issues. Has a nice supple feel, and I do not notice any squishiness.


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## pdxmark (Aug 7, 2013)

175lb to 180lb, sometimes 185lb. Concrete, just below max rated on both tires. Back, Dirt; 35psi to 45psi, sometimes 50psi, depending on terrain, density of soil and/or mud. Front, dirt; 48psi, unless using 50pis+ on rear--again, dependent on soil conditions--.


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## shredjekyll (Jun 3, 2012)

Never more than 33 in the back and 29 out front. I am 180-185 geared up and deal with a good amount of sharp rocks at high speed on every ride. The only flat I have had in the past 4 years was from running over 35 in the back... My strava times have shown me over and over again that low pressures are significantly faster for the areas I frequent. By the way, I use a maxxis freeride tube in the back with a 2.25 exo ardent, and a 2.1-2.4 DH tube up front that came on my slayer with a 2.4 HR2 or sometimes a 2.25 ardent up front. I do ride more AM than XC but the pressure doesn't change between the two I like to set and forget.


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## bad andy (Feb 21, 2006)

such a subjective question with too many variables; Tires, tread, tread width, sidewall thickness, rubber durometer, terrain, rider weight, etc. 

Nonetheless I ride tubeless 28 or so rear, 26 or so front. works for me with my local rocks.


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## Psychotext (Sep 21, 2012)

I was thinking about this whilst switching tyres today. On the sides they had the usual 35-60 psi range and I honestly don't think I've ever ridden with either tyre at even the bottom part of that range for anything other than testing. The only time I ever tend to put 30+psi in my rear tyre is when I know that the trail is going to be without technical sections.

I did recently try a few loops around a local cycle path and I lost about 5 minutes (over an hour) with higher pressures as I couldn't get the power down properly on the gravelly ascents. Dropping the rear to about 32psi stopped the bike feeling like it was bouncing around (on a relatively flat surface!) and I was definitely quicker.


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## RSAmerica (Aug 24, 2012)

I run 19 front / 23 rear with 2.35 x 650b tubeless on my hardtail. I weight ~155lbs. Try what Stan's says. Divide your weight by 7 and take off 1-2 psi front and add 1-2 psi in the rear.


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## zink (Sep 14, 2011)

165 lbs and have been experimenting with a 2.35 Hans Dampf SnakeSkin front and a 2.2 Geax Saguaro TNT rear for snow riding on my rigid 29er, Haven UST rims. 22 psi rear rides well without looking like it is completely flat while 18 psi front is as low as it will go without burping and even lower would be better.

One thing I've noticed with the Saguaro is that the direction of the tread makes a very noticeable difference. I switched it to the "traction" direction and suddenly the back end slides out sideways much more easily while cornering and using the rear brake.


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## SS Hack (Jan 20, 2012)

Running around 18 to 20 front and about 21 to 23 back on 29ers. I weigh 165 geared up. 

I meet a guy running 65 on a 26er the other day and I don't see how he gets any traction. I'll be toast down hill and could climb much either.


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## engrmariano (May 8, 2011)

200lbs 2.4 x-king 18 & 20 psi


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## wahday (Mar 23, 2012)

That MTB Tech site was pretty helpful. I still run about 2-3psi lower than they say, but I know I am in the zone. I really just go by feel, but make note of the pressure when I hit the sweet spot.

The site also confirmed my experience which is that low pressure on a 26” is different than a 29”. I have both and run the 26” (tubeless on WTB Frequency i19 rims with Geax Akas) at about 27/28 and it feels great. But I run the 29er a good deal lower at 24/25 to get the same feeling (tubeless on Stan’s Arch rims and Maxxis CrossMark). Overall, I like the feel of the Aka the best, but it wears REALLY quickly.


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## NordieBoy (Sep 26, 2004)

wahday said:


> That MTB Tech site was pretty helpful. I still run about 2-3psi lower than they say, but I know I am in the zone.


Really? I run about 10psi lower than they say.


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## wahday (Mar 23, 2012)

NordieBoy said:


> Really? I run about 10psi lower than they say.


There are a lot of factors like tubed v. tubeless, tire size and rider weight but I definitely couldn't drop another 10psi from what they recommend. They said 29 or 30 for my 26". I definitely couldn't go down to 19 or 20 on those wheels. Things get squirrelly the closer I get to 25. Similarly, I can't see running my 29er as low as 16 or 17. Though this is a new ride for me and I have been dropping the pressure each day I have been out. 24 is the lowest I have gone on rocky terrain with some good climbing and the extra grip was perfect. But the front end was getting a little unstable in tighter turns on downhill and hardpack. Still figuring it out.


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## NordieBoy (Sep 26, 2004)

wahday said:


> There are a lot of factors like tubed v. tubeless, tire size and rider weight but I definitely couldn't drop another 10psi from what they recommend. They said 29 or 30 for my 26". I definitely couldn't go down to 19 or 20 on those wheels. Things get squirrelly the closer I get to 25. Similarly, I can't see running my 29er as low as 16 or 17. Though this is a new ride for me and I have been dropping the pressure each day I have been out. 24 is the lowest I have gone on rocky terrain with some good climbing and the extra grip was perfect. But the front end was getting a little unstable in tighter turns on downhill and hardpack. Still figuring it out.


Day to day on my fully, I run 24f/29r and for racing on the hard tail, 21f/24r.
Both with tubes and 180lb rider.

When I was running tubeless on the fully, most tyres were best for me about 25psi on the rear, except for a Hutchy Python which had a sweet spot around 29psi.

Lots of figuring out involved...


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## matto6 (Dec 28, 2013)

The advice "Lower your pressure until you experience pinch flats" makes sense if you're running tubes. But what if you're tubeless? "Lower your pressure until you destroy a rim" is not a very palatable answer.

How does one balance the desires to 1) experiment with pressures, and 2) not destroy their expensive rims?

I'm guessing gently bottoming out isn't a problem, so the key is to learn what that feels like and avoid it?


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## J.B. Weld (Aug 13, 2012)

matto6 said:


> I'm guessing gently bottoming out isn't a problem, so the key is to learn what that feels like and avoid it?


That's what I do. If I feel a rim strike or 2 on a ride I know I'm running a couple psi low. Also if it starts feeling squirrly in corners. I haven't damaged any rims due to this, it seems pretty obvious if it's dangerously low.


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## coxinio (Feb 4, 2013)

matto6 said:


> The advice "Lower your pressure until you experience pinch flats" makes sense if you're running tubes.


Not sure this makes any sense at all! The last thing I would want when out on the trail would be a flat to fix and risking a ruined tube. Not good advice in my book.

I run tubeless between 26-30 psi as the trails I ride are generally more rooty and fast rolling. When I was tubed it would be in the 35-40 psi range.

Sent from my Nexus 4 using Tapatalk


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## J.B. Weld (Aug 13, 2012)

coxinio said:


> I run tubeless between 26-30 psi as the trails I ride are generally more rooty and fast rolling. * When I was tubed it would be in the 35-40 psi range.*


I used to do that back in the 90's, tires were a lot skinnier and good info was harder to come by then though. 25 psi for me with 2.2/2.3's, and I have yet to pinch flat due to this.


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## coxinio (Feb 4, 2013)

J.B. Weld said:


> I used to do that back in the 90's, tires were a lot skinnier and good info was harder to come by then though. 25 psi for me with 2.2/2.3's, and I have yet to pinch flat due to this.


Good advice and old habits die hard, will try lowering pressure next time I'm running a tube.


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## jeremyreed (Jan 5, 2014)

Im 220 on 2.0 tires on my cannondale.whats a good pressure I could run on the trails?

Jeremy Reed


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## shiggy (Dec 19, 1998)

jeremyreed said:


> Im 220 on 2.0 tires on my cannondale.whats a good pressure I could run on the trails?
> 
> Jeremy Reed


Read this thread. It tells you how to find what works for you.


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## NordieBoy (Sep 26, 2004)

shiggy said:


> Read this thread. It tells you how to find what works for you.


Good thread, thanks


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## jeremyreed (Jan 5, 2014)

I have mine both at 40 now..rated low is 33psi and high is 55....

Jeremy Reed


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## Stark (Apr 29, 2008)

Conti XKing 2.2, 175lb, 25f/28r. (tubes)


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## NordieBoy (Sep 26, 2004)

At the moment, on the hard tail, Conti X-King 2.4's (55mm width, with tubes), 17psi front, 21psi rear.
16f/20r and I got a couple of rear rim strikes when seated.

87kg, fast(ish) cruise speed, rocks and roots only a couple of cm high.

On the fully, Hutchy 2.1's, Toro front and Bulldog rear. Both tubed. 20f/24r.


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## cnitram (May 16, 2012)

20 front / 25 rear...tubeless


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## NordieBoy (Sep 26, 2004)

cnitram said:


> 20 front / 25 rear...tubeless


What tyres/widths?


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## sroc3 (Feb 28, 2014)

I run Hans Damf 2.35 Front and NN 2.25 Rear. I weigh 155 with all my gear. I used to run 25 front and 28 rear. After my rear losing traction every now and then, and my current rides getting hotter as the ride progresses, I've lowered my pressures to 21/23 respectively. The air inside the tires expands with the heat and the tires do feel harder after the ride. I find that this is perfect for my riding style, terrain and ability - moderately aggressive/dry, loose gravel/intermediate skills.


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## ki5ka (Dec 17, 2006)

I think for some people, a flat, a ruined tube, or a dinged rim is a big deal, for others, its just part of the experience; a good explanation why there are such widely ranging ideas of what is the "right" pressure.


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## SDMTB'er (Feb 11, 2014)

220 geared up. Start rides with 25 front, 30 back, but may reduce pressure if conditions dictate (my non scientific system is to do a five count while pressing in the valve which equals roughly 5 psi). Happened yesterday - bone dry here in SD and a lot or the trail was loose rocks and I was bouncing / skipping around and under steering. Using hookless carbon rims, Hans Dampf 2.3 up front, Racing Ralph 2.2 in back. I have to say I much preferred the ride of the lower pressure and even though I was at approx 20 front, 25 back. Unless you are flying off 2 plus foot jumps or are slamming your bike into everything, the lower pressure (tubeless) should be good to go as far as flats.


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## MSU Alum (Aug 8, 2009)

For tubes, run as low as you can without pinch flatting. That'll be your limiting factor. For tubeless, go as low as you can without having the tire roll under while cornering, or without feeling like it's wandering. It'll change on different width rims. I can go lower on 21 mm rims than I can on 17 mm rims with the same exact tire.


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## XTERRAGreg (Sep 4, 2014)

Guess i have been on road/TT bikes too long... I still have a "mental" issue going below 30psi on my tubeless setup.. All I can think about is rolling resistance.


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## Back2MTB (Jun 4, 2014)

Yep, you have. Different ballgame.


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## NordieBoy (Sep 26, 2004)

XTERRAGreg said:


> Guess i have been on road/TT bikes too long... I still have a "mental" issue going below 30psi on my tubeless setup.. All I can think about is rolling resistance.


I have a 30psi mental barrier too, but mine is the opposite. If I have to, I'll put 29psi in, but I can't put 30.


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## Givmedew (Sep 4, 2014)

XTERRAGreg said:


> Guess i have been on road/TT bikes too long... I still have a "mental" issue going below 30psi on my tubeless setup.. All I can think about is rolling resistance.


Doesn't increasing the pressure increase the rolling resistance? Since when you hit an imperfect part in the road it forces the tire to push up into the bike instead of the tire conforming to the road.

Am I wrong?


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## 127.0.0.1 (Nov 19, 2013)

Givmedew said:


> Doesn't increasing the pressure increase the rolling resistance? Since when you hit an imperfect part in the road it forces the tire to push up into the bike instead of the tire conforming to the road.
> 
> Am I wrong?


you are correct.

I run TT on road and there is one 10 miler upstate NY which is fresh paved and almost zero road imperfections (occasional cow pies that is it) I run >180psi on that road and get my best TT times. if I run these boneshakers anywhere else where there are cracks it not only annoys me but does seem to slow me down, so I use 120psi everywhere else

there is always sweet spot between: too low pressure and obvious wasted effort, a conforming and optimal pressure for the road/trail conditions, and high pressure where bouncing and deflection robs you of forward watts


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## Back2MTB (Jun 4, 2014)

and of course in mountain biking correct tire pressure can often be the difference between riding and walking. too high or too low can cause this to happen but especially in technical singletrack lower pressure can be a huge benefit


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## Givmedew (Sep 4, 2014)

Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40

I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.

So I just let him do it.

Anyways 

Was he right since maybe he knew more about the track than me?

It was mostly dry and very packed dirt/clay. Smooth and hard with a few nasty mud pudals in the low areas. There where some tree roots that you hit hard and some come at the tire from the side.

What if anything did I gain from increasing the tire pressure that high and what did I loose?


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## CrozCountry (Mar 18, 2011)

Givmedew said:


> Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40
> 
> I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.
> 
> ...


First, 30 front and 25 rear is the opposite of what you should have, rear takes more pressure normally.

What you get with higher pressure is pinch flat resistance, better rim protection and stability in turns.

What you loose is traction mostly. Especially over sideways impacts, the tire will bounce to the side instead of deflecting around the side impact.


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## Givmedew (Sep 4, 2014)

CrozCountry said:


> First, 30 front and 25 rear is the opposite of what you should have, rear takes more pressure normally.
> 
> What you get with higher pressure is pinch flat resistance, better rim protection and stability in turns.
> 
> What you loose is traction mostly. Especially over sideways impacts, the tire will bounce to the side instead of deflecting around the side impact.


I just assumed that having front suspension meant it was ok to have a higher front pressure. The bike is a hard tail.

I am running tubeless and pinch flat is tubes right?

Also I do weigh 210LBs if that matter and tend to keep my but on the seat most of time.

Is 25LBs too low? Should I actually be running a higher pressure in the rear than the front?


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## skiwi (Mar 8, 2010)

Givmedew said:


> Well anyways... I am from the road world and just got into MTBs. So today I was riding and my bike was set to 30 front and 25 rear. My friend knowing I was a newb to MTBs said my pressure was to low and inflated my tires to 45/40
> 
> I didnt want to argue and tell someone that rides 10 times a week for the last 20 years that he was wrong.
> 
> ...


He was wrong.

By having less pressure in the tyre, you increase the contact patch which means more traction & braking (longitudinal force) and cornering (sideways force). This is ALWAYS true (simple physics).

However, once you get tyre pressure too low you suffer 2 consequences - one that everyone talks about, and the 2nd one that most don't. The first one is pinch-flats - these CAN be an issue but not if you run tubeless - then you might get a "burp" when the sidewall loses sealing. The 2nd consequence is loss of cornering precision, particularly if the front is too low. A squirmy front end doesn't help XC speed.

I weight 90kgs and run front and rear between 25 to 30 psi depending on the conditions. Looser, then I go lower, harder then higher.


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## redd4573 (Apr 15, 2012)

Givmedew, just use what feels right. There is no magic numbers to chase. Each tire response is different and each riders riding stye is different. I do ride with the front tire inflated about 5 lbs more somtimes because it just works for me. If your buddy is a good rider and has been riding for twenty years then as a beginner that a great place to start. I hope your liking the dirt side on two wheels.


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## Givmedew (Sep 4, 2014)

redd4573 said:


> Givmedew, just use what feels right. There is no magic numbers to chase. Each tire response is different and each riders riding stye is different. I do ride with the front tire inflated about 5 lbs more somtimes because it just works for me. If your buddy is a good rider and has been riding for twenty years then as a beginner that a great place to start. I hope your liking the dirt side on two wheels.


There is no way I am going to be able to judge what feels right the first time on the bike. The tires recommendation is very broad.

To my friend riding for 20 years...

He doesn't pretend to be a pro. But I know people who have done things their whole lives the wrong way. I am a very technically minded person and am always mindful of every little thing.

The tire recommends up to 65 pounds. I reading people running as low as 20LBs. When I went on a demo ride of a RIP 9 NINER a few months back someone on the ride with a tubeless had exactly what someone was describing where suddenly the tire went completely flat.

Just trying to wrap my head around an entirely new world for me.

Going off my butt dyno isn't going to work the first ride or even the first year of riding.


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## Osco (Apr 4, 2013)

After reading all this I dropped from 30 psi front and rear to
28 rear
26 front

No pinches, less root skipping and a bit more side bite in the smooth stuff.
Running Rocket Ron's 27.5 and full suspension.
I'm 185 with 100 oz's of water and gear in my Camelbak volt and ride gear, bike Is at 30 pounds


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## Back2MTB (Jun 4, 2014)

Osco said:


> After reading all this I dropped from 30 psi front and rear to
> 28 rear
> 26 front
> 
> ...


I run that pressure and I'm 210 and on a 29er HT. High volume tires though, 2.3"+and tubeless


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## nauc (Sep 9, 2009)

I run my tires so that they bulge a little bit when I look straight down at them, while on my seat. Seems to work so far


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## NordieBoy (Sep 26, 2004)

nauc said:


> I run my tires so that they bulge a little bit when I look straight down at them, while on my seat. Seems to work so far


I run my stomach that way too...


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## sroc3 (Feb 28, 2014)

just to add ....... since I perfectly dialed it all in.

I ride a TREK EX7, I weigh 155 w/ all my gear

Tubeless Setup - 29er

Hans dampf Front - 18 psi (2.35)
Nobby Nic Rear - 20 psi (2.25)

Works flawless and I ride a lot of XC and do some fairly steep climbs and FAST downhill trail runs (no boulders).


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## 127.0.0.1 (Nov 19, 2013)

tire pressures mean nothing unless you post complete tire size

a 26 inch 1.9 35psi feels the same as a 27.5 2.4 at 25 psi as far as firmness and
bounce on trail (to me anyway)


so, all these pressures in this thread, if there is not the fatness of tire listed it is not that informative. 

vredestein black panther extreme TLR 27.5 2.2 inch 25psi feels about right for XC chunder


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## NordieBoy (Sep 26, 2004)

127.0.0.1 said:


> so, all these pressures in this thread, if there is not the fatness of tire listed it is not that informative.


Also the width of the rim and whether tubed or tubeless...


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## Motivated (Jan 13, 2004)

17-20psi in my NobbyNic 2.35s on Derby 29er rims. Tubeless. Hardtail in the Alps. I weigh 185lb.


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## dmar123 (Mar 30, 2009)

I run tubeless 27.5 with 2.3 High Roller II tires on ENVE AM rims...For long climbs or flat xc riding I usually air up to about 35psi rear and 32psi front. 

For long descents I air down to about 28-25psi in the front and about 30psi in the rear. Anything less and the tires start to get squirmy in turns. 

I have gotten snake bites in the actual sidewall of tubeless tires when running to low of air pressure and start banging rims on rocks. Don't know how people running 20 psi in the rear tire don't thrash their tires and rims, maybe on buff single track thats ok.

When airing down the tires at the top after a long climb I do the squeeze test on the tire and go by feel. 

Pressure depends on your tires, bike setup, riding style, personal preference, and terrain. There is no right or wrong answer. Play around with different pressures and find whats right for you.


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## Gregon2wheels (Jan 17, 2013)

In praise of higher tire pressure - I ran 40 psi (highest safe pressure on Stan's rims per Stan's) just because I was too lazy to tune the pressure after doing a road ride with my son.

With the trails dried out -- WOW! Yes, I gave up some traction, and, no, these are not technical trails besides some roots. What I gave up in straight line traction I made up for in fast turning on the tight corners built into these trails. So much fun and so responsive.

It's not a setting I'd use all the time, but on trails I know with hard conditions, it was fun!


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## AJ541 (Sep 10, 2003)

I ride a 29er FS Trek Superfly on XC trails that have a few rocks and I run the pressure on front and back at around 22 to 30 psi with tubeless ready tires. 1.95 - 2.2 sized tires. Rarely go above 30 psi unless I plan on riding mainly on the road/paved path.


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## Osco (Apr 4, 2013)

On my Scott Spark 27.5, I am 190 lbs In ride gear and a full pack.
Rims are 24mm O.D. and I think 20mm I.D.

I don't have sharp rocks but I got roots of all shapes n sizes.

Running 2.25 Rocket Ron's tubed, at 28 rear 27 front I don't pinch.
Any lower and I get squirmy In turns. Above 30 psi front or rear and I skip off things.
I don't care to go tubeless but with wider rims I may

I am wanting wider rims, say 30-35mm O.D.,, 25-30mm I.D.
My Motocross background tells me wider rims are a smart mod.

Just saying...


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## NordieBoy (Sep 26, 2004)

26x2.3 X-Kings on 18mm id rims (rigid single speed).
20r/16f is good for the bumps, but as I found today, it's easier to (almost) roll a tyre at 16psi.
21r/18f may be safer...


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## nauc (Sep 9, 2009)

while sitting on my bile, looking straight down at my tires, i let out enough air, so the tires bulge a little bit. no idea what psi it is, dont care


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## Back2MTB (Jun 4, 2014)

nauc said:


> while sitting on my bile, looking straight down at my tires, i let out enough air, so the tires bulge a little bit. no idea what psi it is, dont care


You sir are hardcore, well played.


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## Scottwax (Jan 18, 2009)

When I got my MTB, the bike shop set the pressure at the recommended 50 psi (according to Continental's website) which was fine at the time given the local MTB trail was closed and I was limited to pavement the first few rides. However, I did notice once the trail opened up the back end felt a bit loose when I'd accelerate so I'll be dialing the pressure down. Don't want to get to the point where I pinch flat though, I ride my bike to the trails since I live so close and bringing a floor pump to play with tire pressure really isn't an option for me. Maybe start at 35/40 psi and go from there? I am running tubes, just starting MTB coming from road so I want to see how much I like this (so far so good) before I start laying out money for better wheels and going tubeless.


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## BikeIntelligencer (Jun 5, 2009)

*MIT Formula*

An MIT professor assigned this issue to his class and they came up with the following formula, where x=rider weight, y=wheel size and z=tire width.

x times y divided by z times .01 (1 percent)

This assumes tubeless.

So a rider weighing 185 riding 29er on 2.2 tires would run 24 psi.

A rider weighing 210 riding a 27.5 bike on 2.35 tires would run 25 psi.

A lightweight rider at 165 on a 26er and 2.1 tires could get by with around 20 psi.

Note that this applies to overall riding, not strictly XC. It is a general rule of thumb as well, since the MIT team could not factor in such unquantifiable variables as riding style, surface type and rider intelligence, although they did suggest that the higher the IQ, the less applicable the formula is...


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## matto6 (Dec 28, 2013)

BikeIntelligencer said:


> An MIT professor assigned this issue to his class and they came up with the following formula


Finally! I don't know how mountain bikers have gotten by all these years without a bunch of MIT students using a math model to tell them what tire pressures to run.


BikeIntelligencer said:


> x times y divided by z times .01 (1 percent)


All those brains and they ended up with a simple linear relationship? Boooo. If you're going to overcomplicate something you might as well do it right.

Btw, what does this formula attempt to optimize? Rolling resistance? Traction? Feel? 


BikeIntelligencer said:


> although they did suggest that the higher the IQ, the less applicable the formula is...


Because if you have a brain you know to ignore such a silly formula?


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## CrozCountry (Mar 18, 2011)

I would expect MIT guys to know a simple fact that the pressure on the front and rear is different, so there should be two separate formulas for front and rear (just by another simple fact that there is more weight on the rear). Other formulas already account for that, so that's not exactly rocket science.

How many students passed this class?  Actually what class was it?


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## Osco (Apr 4, 2013)

Scottwax said:


> When I got my MTB, the bike shop set the pressure at the recommended 50 psi (according to Continental's website) which was fine at the time given the local MTB trail was closed and I was limited to pavement the first few rides. However, I did notice once the trail opened up the back end felt a bit loose when I'd accelerate so I'll be dialing the pressure down. Don't want to get to the point where I pinch flat though, I ride my bike to the trails since I live so close and bringing a floor pump to play with tire pressure really isn't an option for me. Maybe start at 35/40 psi and go from there? I am running tubes, just starting MTB coming from road so I want to see how much I like this (so far so good) before I start laying out money for better wheels and going tubeless.


This happens to many new riders I bet, bike shop going for lots of psi.

I'd say a baseline starting point for a 200 pound rider including full gear on any 2.2" or up tire in 26, 27.5, 29er tubed and not riding really big hits in rock gardens should be 30 psi front and rear. Ride that for a whole day, carry TWO tubes, pump and tools.

Next ride drop two psi at each end and see what you feel, ride that for two full rides, go by feel, handling.
Too much air makes my bike feel disconnected, jittery, The back end skips off roots kicking the rear about some this way or that.
I actually feel the front tire difference the most when dropping/leaning into a corner.

I'm down to 26 psi front and rear now. No pinches, feels better.

Now at this psi, the change in feel by dropping just one more pound of air was so profound I am ready to go tubeless...

Still gonna carry a tube.


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## windsailbike (Jun 7, 2015)

*About your tire pressure*

The pressure depends on some reason:
1.your weight;2.the temperature 3.Stiffness and structure of your bike rims

suggest no more than 40 PSI if everything is in normal.


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## Givmedew (Sep 4, 2014)

Osco said:


> This happens to many new riders I bet, bike shop going for lots of psi.
> 
> I'd say a baseline starting point for a 200 pound rider including full gear on any 2.2" or up tire in 26, 27.5, 29er tubed and not riding really big hits in rock gardens should be 30 psi front and rear. Ride that for a whole day, carry TWO tubes, pump and tools.
> 
> ...


Yeh carry a tube even if your running tubeless. Or at least bring it with or make sure someone has a tube. I make sure someone in our group has a tube and co2 inflator or pump.

I don't carry 2 unless I'm going far. If your going 10-20 miles from your car then sure 2 tubes for a group of 2-4 riders but if your only going to be 1-3 miles I would just make sure 1 tube is available. It doesn't matter what size it is either. If someone has a 26 w/ them that's enough.

I've never had a tubeless fail but it does happen. If I did a century id cary 2 with and my own pump or atleast an adaptor for my shock pump.

Sent from my iPhone using Tapatalk


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## Psychotext (Sep 21, 2012)

Funnily enough, I've been riding tubeless recently and it's scary to me just how low I've had to go to stop feeling like I'm being bounced around all over the place.

Right now I'm running 20 up front and 24 on the rear.


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## NordieBoy (Sep 26, 2004)

My Hutchy Python's had a sweet spot around 24f/26r whereas the Mich Wild Rac'r Advanced Ultimates needed to be around 20f/22r for the same feel.
The Hutchy's have great pedaling traction and a nice ride, the Miche's only downfall is cornering, braking and acceleration.


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## Givmedew (Sep 4, 2014)

NordieBoy said:


> My Hutchy Python's had a sweet spot around 24f/26r whereas the Mich Wild Rac'r Advanced Ultimates needed to be around 20f/22r for the same feel.
> The Hutchy's have great pedaling traction and a nice ride, the Miche's only downfall is cornering, braking and acceleration.


So your review on the wild racer would be

Title: the tires didn't explode... Yet

Pros: So these tires went fit onto a rim that they where supposed to fit. They have labels so you don't accidentally mix them up with a better tire. They are made from rubber.

Cons: When turning the front washes out and the rear slides. When accelerating uphill the tire spins excessively. When braking the front locks up quick and the rear is mostly useless.

If the purpose of these tires where to protect the rims from scratches while on the show room floor they NAILED IT 5-Stars!

Sent from my iPhone using Tapatalk


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## NordieBoy (Sep 26, 2004)

The Wild Rac'r is light. Very light.
Very good for trail braking into and around corners.

At the speed I race at, it's actually a pretty good tyre.


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## Givmedew (Sep 4, 2014)

NordieBoy said:


> The Wild Rac'r is light. Very light.
> Very good for trail braking into and around corners.
> 
> At the speed I race at, it's actually a pretty good tyre.


Lol good one 

Same back handed comment car and driver gave the rali art...
Car sucks but once you get used to trail braking it then its kind of fun to drive in a pitch and catch kind of way. (Think that was close to their exact words)

Sent from my iPhone using Tapatalk


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## BacDoc (May 31, 2011)

NordieBoy said:


> the Miche's only downfall is cornering, braking and acceleration.


I just got a set of 29 er Wild Race'r advanced Gum X 2.25 . Haven't had a chance to try them out but they look fast, wider than 2.25(compared to my Racing Ralph 2.25) and they feel very light.

The main qualities I look for in a tire are - cornering, braking and acceleration, so your review has me concerned. I mean what else does a tire do if not these 3 important things?

I guess rim protection is highly rated by some LOL!


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## NordieBoy (Sep 26, 2004)

Mine were the 26" Advanced Ultimate. Ultra light, but a sidewall cut means I have to run tubes which defeats the idea of a nice light, responsive tyre.


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## Osco (Apr 4, 2013)

Current setup,
Scott Spark 760 

185 pounds in full ride gear.

27.5 X 2.25 Rocket Ron out back, tubed 25 psi feels great, no pinches.
a 500ish gram tire.

27.5 X 2.35 Bonty XR-3 front, tubed at 23 psi,,, feels great, no snake bites yet
a 700ish gram tire.

Lower than this gives me a squirmy ride, lowest tested so far 23 rear, 21 front, tubed.


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## blackitout (Jun 30, 2014)

Up until today I had always been old school and ran 2.0 to 2.1 tires. Today my 26x2.4(actual 2.33) maxxis ardents arrived and I have to say. I'm a high volume casing convert. I use them on the front at around 28psi and it was amazing what a difference it makes going over rocks and roots at speed. I have 2.1 Ignitors on the back and once they run out of tread in getting 2.2 or 2.3s. It makes such a difference. Now I see why people like high volume casing. It absorbs so much.


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## praivo (Nov 16, 2014)

65 kg rider, 13 kg bike, 27.5"×2.1" Kenda Kadres with tubes, 19/24 psi, no pinch flats yet, even survived a little drop.


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## noobbiker888 (Jul 12, 2015)

I weigh 160 lbs. Specialized Pitch 2015.
Specialized FastTrack 650b, 2.0" tires front and back.
Both at about 23 psi. Ride mostly xc trails. So far no flats after several months.


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## dev-frankenyeti (Dec 5, 2015)

How low pressure could I possibly go?
I weigh 115 pounds and my bike weighs around 30.
I'm running continental 26x2.2" tires tubeless W/ Stan's on my hardtail that has an 80mm fork.


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## noose (Feb 11, 2004)

shiggy said:


> Well said!


Indeed! Terrific advice!


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## noose (Feb 11, 2004)

20/22 front rear on stock tires and tubes. Want to run lower but getting some rollover squirm. Maybe tubeless next?


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## J.B. Weld (Aug 13, 2012)

noose said:


> 20/22 front rear on stock tires and tubes. Want to run lower but getting some rollover squirm. Maybe tubeless next?


Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.


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## noose (Feb 11, 2004)

J.B. Weld said:


> Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.


Well my HD 2.35 trail star for the front should be here tomorrow. Maybe I'll get something else for the back too. I would love wider rims but may have to wait for a while.

Sent from my SM-G920W8 using Tapatalk


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## noose (Feb 11, 2004)

J.B. Weld said:


> Tubeless won't fix that. Maybe a different tire or a wider rim could get you there but -20 psi is approaching the limit for most situations IME.


So far 18 psi is working fine on the new HD TS on the front. No squirm and much more grip than the NN Performance it replaces. The rear NN Performance really can't keep up now so I ordered an HD TS SG for the back and going tubeless too. Tubeless and thicker sidewalls should help with rollover and pinch flats I am bound to get running around or just under 20 on the back.


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## cleanneon98 (Jul 12, 2014)

I'll just add this
175lbs with gear
2015 FUEL EX9
Bontrager Rhythm Comp tubeless
Bontrager XR3 experts 2.3 front and rear

Took my bike in for some work, they trued my wheels and replaced valve stems. Got the bike back, go for a ride, terrible. Felt every root, every bump, spinning the tire trying to climb, and worse yet, wiped out 3 times on slower turns.

Get back from my ride, check pressure, they had me set at like 35psi. Dropped it to 25psi, went back out, and it was smooth as could be, quiet, tons of traction everywhere.


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## Tillers_Rule (Sep 11, 2004)

Tillers_Rule said:


> Historically:
> 
> 50F/50R
> 35F/45R
> ...


Interesting looking back and what I was riding with almost exactly 4 years ago.

Since then I got the RIP9 and put the 26'r to the side collecting dust. Cleaned it up a couple months ago, threw some wider handlebars on it and dropped two of the front chain rings (would only ever use the middle ring).

PSI for my Niner is usually ~34R and 31F. Now that I'm back on the 26'r I've been playing with it's PSI, last time I think I was at 41R and 34F.

My riding has improved and style has changed. I used to just blast through the trails as fast as I could. Now we jump, try out skills at balancing, work on sections, etc.


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## targnik (Jan 11, 2014)

I weigh 235lb's in my birthday suit...

I also advocate for the tyre determines the required pressure.

2.4's I've run in the past @ 22-24psi... 2.35's = 23-25psi... 2.3's = 24-27psi... 2.2's = 28-30psi...

Plus I run tubes... I get a flat once a year, on average. I run protection variety tyres only. Little extra weight for peace of mind.

Sent from my kltedv using Tapatalk


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## noose (Feb 11, 2004)

Osco said:


> Current setup,
> Scott Spark 760
> 
> 185 pounds in full ride gear.
> ...


I'm the same weight as you and settled in at the same pressure on tubeless HD trailstar front and same tire but in Supergravity on the back. Pleased with grip and ride quality over the rough stuff.

Sent from my Nexus 7 using Tapatalk


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## urban_comando (Nov 12, 2014)

Gregon2wheels said:


> *In praise of higher tire pressure *- I ran 40 psi (highest safe pressure on Stan's rims per Stan's) just because I was too lazy to tune the pressure after doing a road ride with my son.
> 
> With the trails dried out -- WOW! Yes, I gave up some traction, and, no, these are not technical trails besides some roots. What I gave up in straight line traction *I made up for in fast turning on the tight corners built into these trails. So much fun and so responsive.*
> 
> It's not a setting I'd use all the time, but on trails I know with hard conditions, it was fun!


I run pretty much max pressure of whatever tire im on. Currently Ikon 26 x 2.35 @ 60psi and in my experience the skitish behavior of high psi can be overcome by smooth body control and good sense. I do give up some bite on climbs and on some of the hairy corners I take them a bit slower but everywhere else, i'm flying way faster with the increased pressures and not having to pedal so much to maintain speed either. I put down a fair bit of mileage each year and the added bonus of almost never flatting out from tubes and high psi is a double bonus on a 100mile tour. I fly over roots and rocks and hang on tight, set the suspension on the soft side with lots of rebound control to do the job it was made for instead of relying on the tires as springs.

Different strokes for different folks.


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## NordieBoy (Sep 26, 2004)

Wow.
I'd consider 24psi as far to high for a front 26x2.35 Ikon.


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## jochribs (Nov 12, 2009)

LOL! That's a bit like the guy over in the Specialized forum that said his 29x2.3 Fastrak (which actually measure out to a shy 2.2 btw) felt 'supple' at 2 bar (29psi) and his 71kg (156lbs)...

supple he said...

Anyway, not to discredit urban commando...what happened to the data that said that lower pressures actually attributed to faster times because the tire wasn't being deflected as much?


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## urban_comando (Nov 12, 2014)

I figured that post would pop some eyes open and invite the hecklers. Theres nothing supple about my set up thats for sure. Its skittish, but its fast and durable. Also worth noting on loose gravel the high psi is BRUTAL for wash outs around corners, thats probably where they are at their worst. On dirt or even mildly wet loose dirt its a handful but manageable and fun too. I also really like the nevagels @ 50psi on loose terrain they corner excellent, climb and roll quite well but only when its loose. Those tires are slugs on hard surfaces imo. Also in the 2.35 btw.


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## jochribs (Nov 12, 2009)

I'm not meaning to heckle you urban commando. Your post just reminded me of that other one. Actually the way you commented about it, relayed effectively that you were dialing the suspension to help compensate and that it was still a compromise.


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## omarlin29 (Jan 24, 2017)

i run 35 rear 30 front with 2.3 geax sturdy's on my hardtail


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## Back2MTB (Jun 4, 2014)

omarlin29 said:


> i run 35 rear 30 front with 2.3 geax sturdy's on my hardtail


How much do you weigh? 250?


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## noose (Feb 11, 2004)

NordieBoy said:


> 26x2.3 X-Kings on 18mm id rims (rigid single speed).
> 20r/16f is good for the bumps, but as I found today, it's easier to (almost) roll a tyre at 16psi.
> 21r/18f may be safer...


I want to run 16f/20r but am worried about rolling the tire right off the rim. I run 20 and 23 right now without squirm at slower speeds but am riding faster trails starting in the spring.


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## noose (Feb 11, 2004)

Interesting that he is running very close pressure to me. Much faster though which increases my confidence that I won't lose a tire.


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## tramuntana (Mar 11, 2017)

Hi, with 220lb ( bicycle + me) and 2.35 tire, i run 21.2f/23.4r for xc, and 24.9f/27.5r for smooth rolling on good roads. 
I use this android app that calculates pressure with 15% or 18% drop. https://goo.gl/0laa5O


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## J.B. Weld (Aug 13, 2012)

tramuntana said:


> Hi, with 220lb ( bicycle + me) and 2.35 tire, i run 21.2f/23.4r for xc, and 24.9f/27.5r for smooth rolling on good roads.
> I use this android app that calculates pressure with 15% or 18% drop. https://goo.gl/0laa5O


23.4? That's crazy! No less than 23.6 for me.


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## DM-SC (Jan 12, 2004)

I haven't read all of the posts in this thread so I apologize if this has already been discussed...

I've found that comparing tire pressures are problematic, given that tire pressure gauges give such a wide range of pressures. Your gauge may say 24psi and mine could read more or less. 

I had two gauges of the same brand that I purchased at the same time and one read 3-4psi more than the other. Which one was correct? Where either of them correct?


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## stonant (Mar 11, 2016)

most likely neither was correct. You should just use one of them, figure out what pressure works best for the trail on that day and in those conditions, and you will constantly have to adjust for each ride (especially as ambient temperature changes so much). It may seem stupid or not precise enough to grab your tire and squeeze, but because gauges vary so much you should try to memorize how your tire feels at your ideal pressure, so then you can use that as a rule of thumb when using other pumps.


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## frenco (Jan 7, 2017)

I weight 210lb/95kg, ride i27 rims, use 20 psi rear and 19 psi front with Conti RaceKing 2.2 tires in tubeless configuration.
With the previous i19 rims I had to use much higher pressures to prevent the annoying tire rollover effect


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## Nikola777 (Jun 4, 2017)

Unique formula for me.

Find some edge block... or sharp rock in that shape .^.

-Lock out front fork
-Put front tire on midle of rock
-Press front brake on max
-Holding handlebar - squeeze that front tire on peak of rock-block or whatever.
-Push That tire as max as as u can on that rock.

And set preasure, on that level, where u are able with all your strenght to squeez front tire not more than half off travel to edge of wheel. This will be preasure for all around.

For max grip and downhill go on 80% of that travel... if u belive in your wheelset and tires ... and if trail is not sharp rocky and u have tubeless go on 90% or even more of travel. But be ware

For rear preasure add around 15% more psi/bar than on front.


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## oldgearstillrolls (Aug 15, 2013)

I've read all through this thread and my main question is "How can it be possible that my experience is so insanely divergent from every other post here?" I am 50 years old. Been riding MTB for 30 years. I am ~200lb. Vast majority of my time has been spent on 26" tubed tires. If I have less than 60 psi in a 26 x 2.2(ish) tubed tire I will flat on that ride. Every time. I can get away with less in a 29x2.3 tubed. Maybe 50 psi. I recently decided to get modern and bought a new bike. With 27.5x2.8 on sun duroc 40 rims I was getting away with 35-40, though I did flat the front once. The 2.8's felt lifeless and sluggish, though they did have great traction. Felt going to 2.4's was a great time to also try tubeless. Ardent/HRII. Shop recommended 30 psi. I think they were being conservative. I, being very conservative, went with 40 psi. Shakedown proof of concept ride ~1hr felt scary, bottoming on rims, squirmy rear coming out of corners, but no flats so why not give it a shot. 30ish mile out and back (on admittedly rooty, rocky trail) at 40 psi. Nearly constant pranging of rims, all kinds of squirming in corners (enough that I ate **** a couple of times when the bike wouldn't hold a line), but no flats. After two rides the rims are pretty much trashed. They'll never be true again but can probably be made rideable. 

How can anybody, let alone ALL of you, be riding sub 30 psi? Granted I am big (6-2/200), posess little finesse and less inclination to use what little I have, and ride chunky trails. But I am also old = relatively slow and cautious. I read these posts like, "yeah, running 18f/22r with tubes and no problems" and Dude. You and I live on different planets. 18 psi I'd flat at the trailhead. Seriously. Somebody explain this to me.


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## NordieBoy (Sep 26, 2004)

Is your gauge 20psi out?
I run 22psi front and 24-26psi rear on the 26" at about 185lbs.
Never pinch flatted yet.
On the 29er, I can run as low as 18-20f and 20-22r.


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## oldgearstillrolls (Aug 15, 2013)

NordieBoy said:


> Is your gauge 20psi out?
> I run 22psi front and 24-26psi rear on the 26" at about 185lbs.
> Never pinch flatted yet.
> On the 29er, I can run as low as 18-20f and 20-22r.


no problems with gage accuracy. 26 with tubes=60psi or flat. thats been proven true for me over decades of riding. less experience on different wheel sizes. only had a niner 2 years and the new 27.5 a few months. your pressures... you've got to be kidding me. that's got to be tubeless. with tubes id flat immediately, like on the first bump at those pressures. Tubeless it'd be trashed rims after one ride for me. are your trails super buff? mine are scattered with fist size + square edged embedded rocks, enough that it's not feasible to try to avoid them all... I tend to miss or loft over the bigger ones and plow through the rest.


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## oldgearstillrolls (Aug 15, 2013)

also the steering is scary. feels great until vrrrrpppp and the whole wheel shifts a couple inches over and I feel and hear the rim hard on the ground and its all vague and unpredictable, like riding a flat tire. ok when just the back does it as that tends to just tighten up the turn a little, but the front rolls off and I am all of a sudden blowing off the trail on the high side of the turn


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## J.B. Weld (Aug 13, 2012)

oldgearstillrolls said:


> I've read all through this thread and my main question is "How can it be possible that my experience is so insanely divergent from every other post here?" I am 50 years old. Been riding MTB for 30 years. I am ~200lb. Vast majority of my time has been spent on 26" tubed tires. If I have less than 60 psi in a 26 x 2.2(ish) tubed tire I will flat on that ride. Every time.


I don't know, you say your gauge is correct so I'll take your word but just realize that you are in the extreme minority and those are some very unusual tire pressures to say the least. "back in the day" when crappy 1.9 tires were the norm I'd run them in the 40's to avoid pinching but I can't imagine running a 2.2 tire @ 60psi. Actually I can't envision riding a 2.2 tire @ 60 psi under any circumstance, even on the road.

I'm pretty skinny but I know a lot of guys your weight and more that keep their tires in the 20's and they do not ride conservatively. Time is ticking, you owe it to yourself to get some good tires and run them at reasonable pressures, no way could you bottom out a rim on decent 2.3 tires @ ~30 psi even if you were a very aggressive rider.


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## oldgearstillrolls (Aug 15, 2013)

Ok I'm an idiot. 

I went and checked my pressures again. Rear was lower than front. I think it burped at some point yesterday when I was wallowing through the corners. Both my gauges matched each other on both tires. But I decided I cant possibly be this different from the whole rest of the internet so I set the regulator on my compressor to 40 psi and dug through my crap and found a schrader adapter and used that to check pressure - both bike gauges are reading wrong by about 15psi. So my "40" was probably about 25. Thanks for the feedback. I don't think I'd have guessed I had two bad gauges bad by the same amount without hashing through it here.


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## NordieBoy (Sep 26, 2004)

My "safe" pressures (tubed or tubeless) for rocky races are around 24f/26r.
We have one 20min descent that's called Boulder Valley for a good reason.


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## Rockohaulic (Oct 26, 2009)

oldgearstillrolls said:


> Ok I'm an idiot.
> 
> I went and checked my pressures again. Rear was lower than front. I think it burped at some point yesterday when I was wallowing through the corners. Both my gauges matched each other on both tires. But I decided I cant possibly be this different from the whole rest of the internet so I set the regulator on my compressor to 40 psi and dug through my crap and found a schrader adapter and used that to check pressure - both bike gauges are reading wrong by about 15psi. So my "40" was probably about 25. Thanks for the feedback. I don't think I'd have guessed I had two bad gauges bad by the same amount without hashing through it here.


I would think your bike pump gauge and your tire pressure gauge would read much closer.

I bought a digital tire pressure gauge, and my analog bike pump gauge tracks pretty closely to the new digital gauge.

I trust the new digital gauge as my true tire pressure.


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## Rockohaulic (Oct 26, 2009)

oldgearstillrolls said:


> Ok I'm an idiot.
> 
> I don't think I'd have guessed I had two bad gauges bad by the same amount without hashing through it here.


Are you using the old "stick" type of tire gauge? Those are notoriously inaccurate.

You should consider getting a digital gauge or an analogue dial gauge. They are more accurate and more precise.

I am 200 lbs with gear. I ride on 27.5 x 2.6 tubeless tires. Front pressure is 21 psi and rear pressure is 25.


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## CrozCountry (Mar 18, 2011)

Rockohaulic said:


> Are you using the old "stick" type of tire gauge? Those are notoriously inaccurate.You should consider getting a digital gauge or an analogue dial gauge. They are more accurate and more precise.


My stick gauge and two digital gauges read within 0.5 PSI of each other. The dial gauge on the floor pump on the other hand can miss by 5.


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## Rockohaulic (Oct 26, 2009)

CrozCountry said:


> My stick gauge and two digital gauges read within 0.5 PSI of each other. The dial gauge on the floor pump on the other hand can miss by 5.


I stand corrected! That is an accurate stick gauge.


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## Rockohaulic (Oct 26, 2009)

*Oldgearstillrolls
*



> no problems with gage accuracy. 26 with tubes=60psi or flat. thats been proven true for me over decades of riding. less experience on different wheel sizes. only had a niner 2 years and the new 27.5 a few months. your pressures... you've got to be kidding me. that's got to be tubeless. with tubes id flat immediately, like on the first bump at those pressures. Tubeless it'd be trashed rims after one ride for me.


I'm confused. Your other post just before this said that *you did* figure out that your gauges were both off by at least 15 psi?

That would answer a lot of your questions........


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## NordieBoy (Sep 26, 2004)

Yes, in his LAST post, he said he found out they were out by 15psi.

You might have the wrong poster in mind?


Rockohaulic said:


> I'm confused. Your other post just before this said that *you did* figure out that your gauges were both off by at least 15 psi?
> 
> That would answer a lot of your questions........


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## Rockohaulic (Oct 26, 2009)

NordieBoy said:


> Yes, in his LAST post, he said he found out they were out by 15psi.
> 
> You might have the wrong poster in mind?


Yes you are correct.

It was the same poster. But for some reason, when I wasn't logged in, the post where he said no problems with gage accuracy was displayed as his last post.

Confusing.

Anyway, makes more sense now. Hope he got it all straightened out.


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## Karlewski (Dec 3, 2016)

WOW,
I ride steep rooty rocky trails in CO, not really XC, 24" drops at least, high speeds till the rocks get to be about grapefruit size or bigger. My weight all up is 165ish, tires are 29er Nobby Nicks 2.35 rear @ 19PSI and 2.6 front @ 16PSI tubeless on 29mm internal carbon rims. I ride very "light" preloading, pumping, hopping and picking clean lines but there's no avoiding many drops and mistakes do happen. I have not flatted or hurt a rim on this set up for 1 full season of major adventure. I am not burping either during fast cornering.
Climbing traction is AWESOME though a well tuned suspension must be helping there.
I think widish rims (about 30mm), quality high volume, 2.3-2.6" side wall protected tires(EXO, snakeskin...), and proper suspension tuning should allow riders my weight to be in the low 20's PSI. The one extra thing I use is the foam Huck Norris Rim protector in my rear tire just in case, I love my carbon rims!
I have been extremely happy with this set up, climbing and descending. On anything but smooth trails low pressure is king for me! Check out what Schwable says on rolling resistance, https://www.schwalbetires.com/tech_info/rolling_resistance
My next wheel build will be as pictured. Huck Norris DH rim protector, 28mm internal, Ultralight Carbon Nextie rims, and a 2.35 Vittoria TNT Barzo rear tire. This light and fast set up will be used on friendlier trails and PSI's in the low 20's. Higher then usual for me on smoother trails with more fragile rims . . . 
As one poster above said, time your descents at various PSI's, your fastest time ought to be the lowish PSI run with a mellower feel to the ride. Use the mellow feeling to relax and bust a move! Hop a water bar or boulder, pre-load/pump then release and float over the little rocky chattery section, use the sidewall of the trail to ramp down and ease the pain on bigger drops, find the "bridges" and unweight over the holes. In simplest terms, whenever it gets interesting, keep your ass off the seat, LOL!


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## dieselhead (Feb 14, 2018)

my setup: 
Rocket Ron 29er 2.25 front and back
22mm inner width rims
Rooty and muddy terrain
rider weight: 145pounds
Front 18psi
rear 19.5psi
could not imaging riding any higher pressures!


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## NordieBoy (Sep 26, 2004)

dieselhead said:


> my setup:
> Rocket Ron 29er 2.25 front and back
> 22mm inner width rims
> Rooty and muddy terrain
> ...


I couldn't imagine being 145lbs.


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## dieselhead (Feb 14, 2018)

```
quality high volume, 2.3-2.6" side wall protected tires(EXO, snakeskin...),
```
why are side wall proteced tyres beneficial over non side wall protected tyres (apart from puncture resistance)?

non protected tyres are significantly lighter and give a much lower rolling resistance:
https://www.bicyclerollingresistance...speedgrip-2017


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## noose (Feb 11, 2004)

oldgearstillrolls said:


> I've read all through this thread and my main question is "How can it be possible that my experience is so insanely divergent from every other post here?" I am 50 years old. Been riding MTB for 30 years. I am ~200lb. Vast majority of my time has been spent on 26" tubed tires. If I have less than 60 psi in a 26 x 2.2(ish) tubed tire I will flat on that ride. Every time. I can get away with less in a 29x2.3 tubed. Maybe 50 psi. I recently decided to get modern and bought a new bike. With 27.5x2.8 on sun duroc 40 rims I was getting away with 35-40, though I did flat the front once. The 2.8's felt lifeless and sluggish, though they did have great traction. Felt going to 2.4's was a great time to also try tubeless. Ardent/HRII. Shop recommended 30 psi. I think they were being conservative. I, being very conservative, went with 40 psi. Shakedown proof of concept ride ~1hr felt scary, bottoming on rims, squirmy rear coming out of corners, but no flats so why not give it a shot. 30ish mile out and back (on admittedly rooty, rocky trail) at 40 psi. Nearly constant pranging of rims, all kinds of squirming in corners (enough that I ate **** a couple of times when the bike wouldn't hold a line), but no flats. After two rides the rims are pretty much trashed. They'll never be true again but can probably be made rideable.
> 
> How can anybody, let alone ALL of you, be riding sub 30 psi? Granted I am big (6-2/200), posess little finesse and less inclination to use what little I have, and ride chunky trails. But I am also old = relatively slow and cautious. I read these posts like, "yeah, running 18f/22r with tubes and no problems" and Dude. You and I live on different planets. 18 psi I'd flat at the trailhead. Seriously. Somebody explain this to me.


Go tubeless yesterday with sidewall protected tires EXO, snakeskin etc. That will let you run lower pressure without pinch flatting or cutting sidewalls and handle cactus etc. 185lbs geared up and 22f and 25r and haven't flatted in two years on two different bikes. I ride light granted but almost all tech sharp rocks in Phoenix all winter so far.

Sent from my SAMSUNG-SM-G891A using Tapatalk


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## NordieBoy (Sep 26, 2004)

Read a little further...


noose said:


> Go tubeless yesterday with sidewall protected tires EXO, snakeskin etc. That will let you run lower pressure without pinch flatting or cutting sidewalls and handle cactus etc. 185lbs geared up and 22f and 25r and haven't flatted in two years on two different bikes. I ride light granted but almost all tech sharp rocks in Phoenix all winter so far.





oldgearstillrolls said:


> Ok I'm an idiot.
> 
> I went and checked my pressures again. Rear was lower than front. I think it burped at some point yesterday when I was wallowing through the corners. Both my gauges matched each other on both tires. But I decided I cant possibly be this different from the whole rest of the internet so I set the regulator on my compressor to 40 psi and dug through my crap and found a schrader adapter and used that to check pressure - both bike gauges are reading wrong by about 15psi. So my "40" was probably about 25. Thanks for the feedback. I don't think I'd have guessed I had two bad gauges bad by the same amount without hashing through it here.


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## noose (Feb 11, 2004)

NordieBoy said:


> Read a little further...


Okay my bad. That's better but still go tubeless unless I missed that also.

Sent from my SAMSUNG-SM-G891A using Tapatalk


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## Karlewski (Dec 3, 2016)

dieselhead said:


> ```
> quality high volume, 2.3-2.6" side wall protected tires(EXO, snakeskin...),
> ```
> why are side wall proteced tyres beneficial over non side wall protected tyres (apart from puncture resistance)?
> ...


 We're entering the trade off zone here. Ideally, rolling resistance is born of supple casings with good elasticity or "rebound" like a basket ball, actually returning energy. Great for bunny hopping, trials bike bouncing around OR XC racing where the tire actually absorbs smallish rocks into the tire, slowing the bike, but then it recaptures most of that energy when the tire rebounds back into shape actually pushing off that same rock/trail imperfection as the tire goes past it. . .For those situations supple casings are key for retaining energy, the tire rubber compound also matters, whole other story about elasticity there.
On the other extreme, hauling butt through a gnarly steep rock garden is most secure with highly dampened casings, ie stiffer, energy absorbing, dead feeling tires. Those characteristics keep you from pin balling off every mean chunck of trail allowing for much greater control. Here obviously suspension helps too but, not so much laterally, side to side.
For the do it all trail rider we're always better off with puncture resistance; that will get us piece of mind. But, a balance must be met concerning the issues above and even more . . . somewhat stiffer side walls (reinforced) gives more tire support allowing for lower PSIs and efficiency (absorbing that rock in the first place), less tire squirm when cornering hard, improved traction and better protection/support to keep from bottoming out on your rim. Wider rims help support any side wall too.

The short answer, puncture resistant side walls gives the added benefit of increased tire support for running LOW PSIs and getting all of those associated benefits.

The trade off for me / us. I love bouncing/hopping up and over trail obstacles climbing and descending, rebound is my friend (personally, I hardly dampen my shocks and that helps me climb) supple casings are great for that. Often I can't spring over everything and have to plow, here some tire dampening is a good thing, especially on the hair raising decent! More like DH/motocross style. In ALL the cases a low PSI (traction and efficiency) is my friend as long as my rims don't ever bottom out and front tire squirm is absent.

Way long winded here . . . in a perfect world with no trade offs, I'd have super light supple casings for my climbs and heavier stiffer, think more supportive and dampening, for the high G corners and widow maker descents. 
On a HUGE constant climb, think 3k feet up roughish terrain to the continental divide, I'll set 14-15 PSI on a 2.6" rear tire, normally foolishly low, and moon buggy my way, up absorbing the chuck. No way am I going to go back down with those PSIs though, I love my rims, out comes the pump. LOL!

Time waster theoretical babble . . .

Theoretically now, I have been thinking way to much over this stuff and I own both a Plus bike and XCish trail bike. In a perfect world with only efficiency and ride quality in mind, I'd run my tire size and PSI's to match the size of the trail debris I plan on running over. If I plan on running over a ton of 2" rock/trail chatter it would sure be cool to have a 3" tire set up to literally swallow 2" rocks never pitching the bike up/altering it's angle of attack/wasting energy at all. There is no perfect world, trail conditions vary wildly and often huge climbs can make the 3" tires unpleasantly heavy. PSI's would HAVE to increase for descending and the odd bigger rock hits. Food for thought though, with new molecular level materials construction and huge innovation these obstacles can be over come.


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## CrozCountry (Mar 18, 2011)

Don't forget the tread. Deep spaced knobs penetrate the earth more and that creates more friction, compared to faster treads that stay more on the top of the soil.

More important on the back where there is more weight on the tire.


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## Halfabrain (Jun 5, 2014)

*Tire Tension vs Pressure (T=PxD)*

I looked back through 2016 posts on this thread and didn't see any references to this video which is the best I've seen r/t wide vs. narrow tires and psi experimentation.

I have typically run a smaller rear tire for faster rolling - but maybe I've been wrong all along? I tried a Minion DHF/DHR Wide Trail (2.5) and felt the larger rear was dragging so changed DHR to an Aggressor (2.35). On 27.5 Ibis 738's, 35mm internal rim width.

As most folks, I run a slightly lower front pressure than rear...or so I thought! (18psi front and 20 psi rear).

Turns out my 'tire tension' was exactly the same! (which may not be a bad thing).

Pressure x Diameter = Tension

Aggressor[R] (20psi) x (2.35[R]/2.5[F]) = 18.8psi

So, if I have the DHF at 18psi = slightly less tire tension in front than rear.


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## Karlewski (Dec 3, 2016)

That is an excellent video, 2nd time seeing it for me, first time I have considered casing tension in depth. If I understand it correctly the casing tension truly dictates the amount of casing deflection. Simply put, how much the casing will absorb or conform around a trail imperfection. 
Here’s the “thing” if you have bigger tires/deeper tires, you can afford more casing deflection before that trail imperfection is going to contact your rim so, running even lower pressures would seem reasonable. That said, obviously there is about 2x the weight on our rear tires and that is also a huge consideration. Tire volume is yet a different consideration. I would assume the air pressure in a lower volume tire would ram up quicker with tire deflection. . . The clear conclusion, trials is likely a simpler way to arrive at optimal pressure for any given tire but, recognizing the variables with greatly improve your trials. . .
On tire tread, clearly tread depth matters but, the elasticity of said tread rubber also plays a roll. Highly elasitc nobbies, to a degree, will return the energy used to compress them. Not all rubber is created equally and a huge area of tire developement in general but, grabbing and displacing dirt will always be an additional cost as stated above. . . I like semislicks for this reason on xc trails.


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## TheBaldBlur (Jan 13, 2014)

Here's a tire pressure question I'd never considered before - Do you guys find that in addition to size, conditions, etc. that tire pressure is a function of tread count?

For example: assume a Maxxis HighRoller II - one in 60tpi and another in 120tpi, everything else is the same. Are you running the same pressure in both tires?

I'm tempted to think that 60tpi tire will tolerate lower pressure than a 120tpi tire. The 120 should be more supple but, other things being equal, more prone to damage. Of course in the case of the example HRII the difference in thread count also comes with a different tread compound.


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## stixxs (Mar 12, 2018)

I like speed over traction. I run high psi's for this reason. 35-45 depending on trail conditions. I am also 6'2" 220 so going too low scares me.


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## J.B. Weld (Aug 13, 2012)

stixxs said:


> I like speed over traction. I run high psi's for this reason.


You might be sacrificing both speed and traction, several tests conclude that lower pressures are often faster.

There are lots of factors of course and I'm not saying you have it wrong but running a little lower psi's hasn't seemed to slow me down at all, actually I'm probably faster on most trails due to better grip. Also a much smoother ride.


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## NordieBoy (Sep 26, 2004)

Higher pressure FEELS faster.

When I first went tubeless, I thought 28psi was brilliant. So soft, supple and felt so fast!
Now, 20f/22r or on a rockier course, 22f/24r. Softer, supplererer and faster.


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## Losvar (Mar 21, 2016)

The correct pressure is the lowest you can run without destroying your rim and/or enough to keep the tire from rolling over in corners. This will vary wildly depending on tire, rim and the rider. Also, don't fret over whatever psi you are reading, it's most likely wrong unless you are using a calibrated gauge that you actually maintain.


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## hesitationpoint (Aug 11, 2017)

Off road, lower psi is faster. The tire conforms over trail imperfections rather than deflects. So low psi, supple tires have lower rolling resistance. High psi is faster on very smooth roads and steel drums, but not when there are bumps, roots, uneven terrain. Lots info on the internet about this.


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## PinchFlatsAllDay (May 5, 2019)

J.B. Weld said:


> several tests conclude that lower pressures are often faster.


Not If you have tyres with the thickness of foreskin and get PinchFlatsAllDay


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## NordieBoy (Sep 26, 2004)

NordieBoy said:


> Higher pressure FEELS faster.
> 
> When I first went tubeless, I thought 28psi was brilliant. So soft, supple and felt so fast!
> Now, 20f/22r or on a rockier course, 22f/24r. Softer, supplererer and faster.


Just checked out the tension and 20f/22r on the 2.35's is about the same as the 28f/30r I like on the gravel 1.75's.
Wow. Maths works. Who knew?


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## jeff92123 (Jul 13, 2012)

This thread has lasted 10 years and in case it goes another 10 may I suggest to include the following information if you are discussing pressures that work well for you. Many have - thank you, the information is helpful. Many have not - and I can't help thinking what is the point?

your weight
tire model and specs (size, tread width)
rim width if you know it
type of riding and terrain

Thanks. That would really help. Of course I'm referring to tubeless. If you're running with tubes in 2019 I'm sorry but nobody cares.


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## NordieBoy (Sep 26, 2004)

Todays XC race in the rain and mud went well with 17psi in the front Butcher Grid 2.3 and 19psi in the rear Purgatory Grid 2.3
A few bumpy sections on the 4km course, a 300m segment of rocks and roots and 2 good g-outs.
78kg rider, i25 rims.


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## mtnking (Feb 10, 2012)

Sometimes I check my tire pressure by squeezing the tires. It's surprised me how low a pressure I've ridden with ... 14-16 psi sometimes. It works fine. I'm 170lbs and pretty careful. My target pressures are 27 frt/28rear. It's a personal preference and based on your weight, tire size, riding style, and terrain.


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## wightweenie26er (Sep 28, 2017)

I run at 35 psi
26 x 2.2 rear/2'' front Conti Race Kings in dry OR
26 x 1.8 rear/1.7 front Conti Mud king rear GEAX mud front 
ride mainly forests 
I weigh 62 kg
I use Revoloop Ultra tubes 42 grams
Extralite HyperTerra wheels


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## WMBigs (Jul 11, 2009)

WMBigs said:


> I don't know how much air I let out when I get to the trail head, whatever feels right. I started to check it when I got home. Found out 18-22 front and 24-27 rear was pretty typical. Much less than the old 1.95x26" pressures.
> Fully rigid. 2.35x29 WTB tires with tubes, Velocity Blunts. 175lbs + weight of bike.
> Every once in while I will feel the front tire bottom on the rim. No pinch flats on front yet. Have had a couple on rear long after the ride has ended.
> Trail is hardpack with river rock. Lots of sharp broken shale rock with a few roots.


Years later, 2.5x29 Minion up front on wide rim gets18psi, 120mm Manitou Magnum. 
2.6x29 Maxxis Rekon gets 20psi. Love the Specialized Fuse set up this way.


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## trmn8er (Jun 9, 2011)

Weigh 225 6’3”
Tires XR4 29X2.3 Team issue front and rear
Roval Traverse SL 30mm internal
XC and fairly aggressive trail riding 
21 psi front, 26 rear


Sent from my iPhone using Tapatalk


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## mhoopes (May 8, 2007)

Similar to poster above, scaled down:

140 lbs., 5’7”
Nobby Nic Snakeskin/Speedgrip TLE 27.5x2.35
Stan’s Race sealant (60 mL ea.)
2016 Roval Traverse SL 30 mm inner
12 psi F, 13 psi R


Sent from my iPhone using Tapatalk


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## b rock (Jan 5, 2017)

WMBigs said:


> I don't know how much air I let out when I get to the trail head, whatever feels right. I started to check it when I got home. Found out 18-22 front and 24-27 rear was pretty typical. Much less than the old 1.95x26" pressures.
> Fully rigid. 2.35x29 WTB tires with tubes, Velocity Blunts. 175lbs + weight of bike.
> Every once in while I will feel the front tire bottom on the rim. No pinch flats on front yet. Have had a couple on rear long after the ride has ended.
> Trail is hardpack with river rock. Lots of sharp broken shale rock with a few roots.


This about matches what I use, but my rider weight is higher, and I don't ride sharp stuff. This is a bigger difference between front and back than a lot of people recommend, but I find it works well with a modern bike that tends to bias weight toward the rear (and can wash the front tire if you aren't working hard to weight it a bit it in dry and loose conditions)

front: 18 PSI
back: 24 PSI
front tire: XR4 27.5 x 2.6
back: Rekon (DC) 27.5 x 2.6
rider with gear: 207
rims: 30mm internal
not riding super fast, no big air or drops
very dry terrain with low traction (loose over hard typically)
I started with this calculator, which is a bit dated now, and kept dropping my front tire pressure whenever I would wash the front wheel out (I use the 29 x 2.2-2.4 setting to approximate 27.5 x 2.6, as that seemed like the closest the calculator could get, based on how it gives the same recommendation for 29 x 2-2.2 as it does for 27.5 x 2.2-2.4):


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## Jayem (Jul 16, 2005)

This is the pressure I'm running right now on my fatbike.


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## JeffHNY (Dec 22, 2020)

Bontragers XR4 Front / XR3 Rear - 29 x 2.4 F/R
SunRingle 36mm IW Front / Giant 30mm IW Rear
13 PSI F/R
DIY 1.5" Inserts
5'7 - 155lbs w/ Gear
Fathom 2 Hardtail - 30lbs
Aggressive XC / Trail - Some big drops and no rim strikes. It's rooty where I ride. Will test higher pressures when it warms up and I'm more inclined to take the abuse.


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## GlowBoy (Jan 3, 2004)

180lb rider. I usually ride the same full-rigid fat/plus bike on the street and on the trails (which I usually reach via the street). Year round. In Minneapolis.

In the summer, for street use I go with the fastest-rolling 2.2-2.6" tires I can get my hands on, maybe at 50-60psi rear and 30-40 front if I am limiting myself to pavement and want to go fast.

For summer mountain biking I'll run 2.8-3.25" tires, at 10-12 psi, if I'm driving to the trailhead. That's about the low end of what I can get away with on my narrow rims; otherwise I might go lower. If I'm biking to the trailhead, more like 12-15psi front and 15-20 psi rear.

In the Minnesota winter, I still ride. On the streets, sidewalks and bike paths, bashing through the various mushy messes left by cars, snowplows and snowblowers. And on the trails, which can vary from several inches of freshie (usually don't try riding that with my 4"-width fatbike) to hardpack and glare ice. Did several miles yesterday, including a couple miles on lakes covered with 2-4" loose powder, with a 29x3.25 in back at 12 psi, and a 26x4.0 at 4psi. Did 25 miles this morning on a mixture of plowed paths and mush-packed trails, with the front tire increased to 6psi to reduce the rolling resistance a bit. 6psi was perfect on the trails when I started my ride at 18 degrees F, but by the end of the ride it had warmed to 25F and trails were getting mushier, pushing the tire around. If I'd stayed out longer I would have dropped the front back down to 4.

So what Jayem said is not necessarily wrong.


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## le_pedal (Jul 10, 2018)

I ride/race XC and am light, 125lb. For an average 2.35 tire I usually run 20f, 22r give or take. This thread makes me think I should be going a bit lower? I definitely have some moments where I feel I get close to rim strikes every now and then (mostly on the rear). This is new england / northeast USA conditions.


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## suprteck (Sep 27, 2009)

le_pedal said:


> I ride/race XC and am light, 125lb. For an average 2.35 tire I usually run 20f, 22r give or take. This thread makes me think I should be going a bit lower? I definitely have some moments where I feel I get close to rim strikes every now and then (mostly on the rear). This is new england / northeast USA conditions.


I'm 135lb and with 27.5x2.30 front 17-18psi. 
27.5x2.25 rear 19-20psi with 25mm rims


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## MSU Alum (Aug 8, 2009)

le_pedal said:


> I ride/race XC and am light, 125lb. For an average 2.35 tire I usually run 20f, 22r give or take. This thread makes me think I should be going a bit lower? I definitely have some moments where I feel I get close to rim strikes every now and then (mostly on the rear). This is new england / northeast USA conditions.


You could go lower, but should you? I guess I'd run different pressures to see what is fastest for your racing conditions. I'm 165 and ride a short travel 29er in Moab at around 13f/17r. I absorb a lot with arms and legs and never get rim strikes on 2.35-ish tires and don't sense the tires folding up under me. I'm hitting plenty of square edge ledgey bumps, but rarely take more than about 3 foot drops. Lots of people say they'll ruin their rims under 25+ psi and can feel tires fold up, and I believe them, so I guess everyone is different.


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## mtnking (Feb 10, 2012)

Lugi said:


> I was curious to know what tire pressure is the best for all around xc use?
> I had IRC Mythos on my K2 and ran them very high because someone told me that I would get pinch flats left and right if I didn't.
> I now have Kenda Nevegals on my Cannondale Rush and was curious where people tend to have their pressure set. I normally ride pretty rocky/root filled technical terrain, with a little mud thrown in once in a while and some nice long downhills.
> Any suggestions would be great. Thanks





MSU Alum said:


> You could go lower, but should you? I guess I'd run different pressures to see what is fastest for your racing conditions. I'm 165 and ride a short travel 29er in Moab at around 13f/17r. I absorb a lot with arms and legs and never get rim strikes on 2.35-ish tires and don't sense the tires folding up under me. I'm hitting plenty of square edge ledgey bumps, but rarely take more than about 3 foot drops. Lots of people say they'll ruin their rims under 25+ psi and can feel tires fold up, and I believe them, so I guess everyone is different.


Exactly. Lot of variables here with terrain, weight, and riding style. Sounds like you found what works best for you.


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## Phillbo (Apr 7, 2004)

I squeeze them.If they feel soft I add air. If they feel firm I ride.


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## NordieBoy (Sep 26, 2004)

2.35 29 EXO Ikons on i25 rims at 18f/20r psi.
2.3 29 Fasttrak/Renegade (non grid or control) combo on i25 rims at 22f/24r psi for same feel. 
Fasttrack Grid on same bike at 17f/19r to get the same feel.

Next test is CushCore XC in the Fasttrak/Renegade combo.


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## Jayem (Jul 16, 2005)

Phillbo said:


> I squeeze them.If they feel soft I add air. If they feel firm I ride.


Impossibru!


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## Mongoguy (Oct 16, 2019)

225
Pivot Les single speed, Niner rigid fork
F~Vittoria Mezcal 2.6 @21lbs
R~Vittoria Mezcal 2.35 @23lbs
I9 eNDURO 305 diameter 30mm 
East Coast SE PA mix of rocks n roots.
Super FAST setup for me, moving from Rekon 2.4 on rear to Mezcal. Only major downfall is the Mezcal doesn't seem to brake as well, but super fast and tough


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## gat3keeper (Jan 24, 2015)

For urban XC race (road or paved), what tire pressure?


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## suprteck (Sep 27, 2009)

suprteck said:


> I'm 135lb and with 27.5x2.30 front 17-18psi.
> 27.5x2.25 rear 19-20psi with 25mm rims


I'm 140lbs riding tubeless 27.5 x2.3 Continental Cross king in Front 18psi 27.5x 2.25 rear Race King 19-20 psi also on 25mm rims.


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## metcalfe (Jun 11, 2017)

165lbs rider
30mm rims

Front 29x2.4 Rekon @ 18psi
Rear 29x2.35 Rekon Race @ 22psi

I ride XC trails, mostly hardpack. Lots of roots, less rocks, some sand.

I tried running the rear down at 20psi but felt like my pedaling started to suffer.


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## gat3keeper (Jan 24, 2015)

For pavement,,, what is the tire pressure xc mtb ?


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## eastman (Jan 17, 2004)

Wow, crazy to see all the different psi for tires. I'm in the 190lb range, fully kitted and have always run 20 psi in the rear and 17-18 psi in the front. 30mm rims w various maxxis tires ranging from 2.3 to 2.5. I know no two pumps provide the same psi, so I recently purchased the digital Topeak, smartguage to compare psi w my pump. turns out my pump gauge reads about 1 psi higher then the gauge. when it's a little damp, I sometimes let even a little more air out during the ride. No pinch flats to date and we ride in MD/PA, so plenty of rocks to contend with.

Our group consists of riders from 120lbs to the heavy hitters, and when conversation topics run low, psi always seems to rear its head. For the most part, it seems that most are in the 20 psi in the rear and 17-18psi in the front. That said, the lighter guys do like to run a little lower then this on the really technical rides, with their fair share of pinch flats.

with that lower psi, they can really roll more effectively over the chunky stuff until they pinch and ask if anyone has an extra bacon strip! Oh well, time for another bite from my smashed up pbj and a new chapter in the psi discussions.


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## MSU Alum (Aug 8, 2009)

eastman said:


> That said, the lighter guys do like to run a little lower then this on the really technical rides, with their fair share of pinch flats.
> 
> with that lower psi, they can really roll more effectively over the chunky stuff until they pinch and ask if anyone has an extra bacon strip! Oh well, time for another bite from my smashed up pbj and a new chapter in the psi discussions.


They're pinching out tubeless at these pressures?


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## eastman (Jan 17, 2004)

MSU Alum said:


> They're pinching out tubeless at these pressures?


Yes, w Stans of plenty. But, please note, they are running lower psi then 20R/18F in those rocky technical situations.


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## MSU Alum (Aug 8, 2009)

eastman said:


> Yes, w Stans of plenty. But, please note, they are running lower psi then 20R/18F in those rocky technical situations.


I've run 13 front, 17 rear in Moab for years at my weight of 160. Getting a rim strike hard enough to cut the side wall is pretty impressive, especially for the lighter guys in your group! I've been running a 29x2.3 Mountain King rear and 29x2.4 Trail King front lately on 27 mm rims with Protection and Black Chili. I've used Nobby Nics and DHF/Aggressor combos at that pressure as well with no rim hits.


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## eastman (Jan 17, 2004)

MSU Alum said:


> I've run 13 front, 17 rear in Moab for years at my weight of 160. Getting a rim strike hard enough to cut the side wall is pretty impressive, especially for the lighter guys in your group! I've been running a 29x2.3 Mountain King rear and 29x2.4 Trail King front lately on 27 mm rims with Protection and Black Chili. I've used Nobby Nics and DHF/Aggressor combos at that pressure as well with no rim hits.


I'm a maxxis guy and do seem to notice more riders having pinch flats with bontrager tires. I haven't been out to moab yet, but some of the rocky trails in MD and PA can be a little sharp!


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## MSU Alum (Aug 8, 2009)

eastman said:


> I'm a maxxis guy and do seem to notice more riders having pinch flats with bontrager tires. I haven't been out to moab yet, but some of the rocky trails in MD and PA can be a little sharp!


They can probably be sharper in Md and Pa. Moab is a place with hundreds of square edges per mile, on fairly high speed straightaways, so it just makes for a good data point.


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## b rock (Jan 5, 2017)

eastman said:


> Wow, crazy to see all the different psi for tires. I'm in the 190lb range, fully kitted and have always run 20 psi in the rear and 17-18 psi in the front. 30mm rims w various maxxis tires ranging from 2.3 to 2.5. I know no two pumps provide the same psi, so I recently purchased the digital Topeak, smartguage to compare psi w my pump. turns out my pump gauge reads about 1 psi higher then the gauge. when it's a little damp, I sometimes let even a little more air out during the ride. No pinch flats to date and we ride in MD/PA, so plenty of rocks to contend with.
> 
> Our group consists of riders from 120lbs to the heavy hitters, and when conversation topics run low, psi always seems to rear its head. For the most part, it seems that most are in the 20 psi in the rear and 17-18psi in the front. That said, the lighter guys do like to run a little lower then this on the really technical rides, with their fair share of pinch flats.
> 
> with that lower psi, they can really roll more effectively over the chunky stuff until they pinch and ask if anyone has an extra bacon strip! Oh well, time for another bite from my smashed up pbj and a new chapter in the psi discussions.


29ers?

I run a similar front pressure but 24-25 in the back on 27.5 x 2.6, but am switching to 2.5 and 2.3 soon. Also rider weight around 190 and i30


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## Swerny (Apr 1, 2004)

trmn8er said:


> Weigh 225 6'3"
> Tires XR4 29X2.3 Team issue front and rear
> Roval Traverse SL 30mm internal
> XC and fairly aggressive trail riding
> ...


Thanks for this.

I'm 220 and just installed a pair of 29 x 2.4 XR4's on my Trance with 30 mm ID rims.

I tried the suggested 30R/28F yesterday on the stock Minions and it felt way too hard.

I'm lost with tire pressure as I've been on 29+ the past few summers.


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## trmn8er (Jun 9, 2011)

Yeah that’s way too high pressure especially with a 2.4. Try 21 up front & 25 rear and see how that supports you. I’m down to like 215lbs and that’s all I usually run. 


Sent from my iPhone using Tapatalk


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## eb1888 (Jan 27, 2012)

Swerny said:


> Thanks for this.
> 
> I'm 220 and just installed a pair of 29 x 2.4 XR4's on my Trance with 30 mm ID rims.
> 
> ...


Experiment. Take a compact frame type pump out on your normal ride. Find the segment with the most rock/roots and some speed. Drop the pressure until you get rim hits riding through the chunk. Front and rear will be different with front tire maybe 4 psi lower. Session the segment lowering the pressure until you feel the rim hit. Then add 1-2 psi.


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## Bob-o-matic (Jun 25, 2021)

Same here... I weigh 215, ride rigid, and recently switched from plus tire [27.5x3.0] to 27.5x2.4 tires and tubeless. I started with 15/18psi f/r ... a few psi more than I used with plus tire. Ive had occational rim strikes and been adding 1-2psi til I don't rim strike.... Currently at 18/22psi.... No strikes yet. The rear tire feels less soggy but traction has decreased. Front has sharper steering. If this is ideal pressure, maybe 29er with same weight rider could use a few more psi. Hope this helps.


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## Suns_PSD (Dec 13, 2013)

Everything else equal you can run 1-3 LESS psi on a 29er vs. a 27.5" tire. 26ers require ever higher pressure.


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## johnstone3 (Feb 11, 2007)

168 lbs on old style, narrow 22mm ID, Roval Control Carbon SL rims on full suspension bike with 130mm travel fork and 120mm travel shock.
XC/Trail riding at SLC-Wasatch Front, Park City, Moab and Hurricane, Utah.

Front: 29x2.4 Bontrager XR4 Team Issue at 22psi
Rear: 29x2.35 Maxxis Ardent Race at 25psi

Working great. Some tables indicate a 2.4 tire is too wide for my 22mm rims, but the 2.4 XR4 on front is cornering great.


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## TheDarkInstall (Mar 8, 2021)

150lbs; 22psi in both seems decent to me. Maxxis Rekon Race on 30mm internal rims.


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## NordieBoy (Sep 26, 2004)

At the moment, 18f/20r psi (+2psi if a bit more protection is needed) in 2.3" Purgatory's (winter tyres) on 25mm rims. 180lbs.
Rode yesterday without checking the pressures and it felt great. Checked when I got home - 16f/18r.


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## crembz (Feb 25, 2019)

I can't understand how people run such low pressure. I'm 190lbs on 29x2.35 and I've bent two rims (one was not salvageable) on my hardtail running 23psi in the rear. I have to run at least 26 in the rear to avoid crying half way down the trail.


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## Suns_PSD (Dec 13, 2013)

crembz said:


> I can't understand how people run such low pressure. I'm 190lbs on 29x2.35 and I've bent two rims (one was not salvageable) on my hardtail running 23psi in the rear. I have to run at least 26 in the rear to avoid crying half way down the trail.


Well for one thing you are on a HT which is much harder on your rear wheel. 
There are many factors including terrain & riding style. 
I also need higher pressures.

Sent from my SM-G715A using Tapatalk


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## NordieBoy (Sep 26, 2004)

crembz said:


> I can't understand how people run such low pressure. I'm 190lbs on 29x2.35 and I've bent two rims (one was not salvageable) on my hardtail running 23psi in the rear. I have to run at least 26 in the rear to avoid crying half way down the trail.


Is your gauge accurate?
I race XC at 18f/20r and rocky/rooty trail rides get up to 20f/22r.


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## crembz (Feb 25, 2019)

Suns_PSD said:


> Well for one thing you are on a HT which is much harder on your rear wheel.
> There are many factors including terrain & riding style.
> I also need higher pressures.
> 
> Sent from my SM-G715A using Tapatalk


Yeah true. Been debating whether to start using inserts it move to tougher casings ... Discussion for a different thread.


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## crembz (Feb 25, 2019)

NordieBoy said:


> Is your gauge accurate?
> I race XC at 18f/20r and rocky/rooty trail rides get up to 20f/22r.


Yeah I have 4 different gauges that read within 1psi of each other


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## angryoldman (Jun 15, 2015)

Hi, question about tire pressures

If you are trying to better your own strava climb, 85-90 percent uphill for 40-45 minutes…
Do you run the same pressure or more since you don’t need the cornering traction as much since you are rolling uphill. As long as you don’t spin out due to too much pressure. My rims are around 24 wide and I usually run 18-19 front and 19-20 rear and i weigh around 154.

Anyone experimented with this for the same climbs using the same tires with different pressure?


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## MSU Alum (Aug 8, 2009)

angryoldman said:


> Hi, question about tire pressures
> 
> If you are trying to better your own strava climb, 85-90 percent uphill for 40-45 minutes&#8230;
> Do you run the same pressure or more since you don't need the cornering traction as much since you are rolling uphill. As long as you don't spin out due to too much pressure. My rims are around 24 wide and I usually run 18-19 front and 19-20 rear and i weigh around 154.
> ...


I use the same pressures for climbing and descending. I'm 165 and my best climb times are 12 front/16 rear. I bump it up 2 psi (or so) when I ride in Moab. Otherwise, after lots of experimenting, that's what works best for me.
I went on a solo ride today that started with pretty continuous climbing.
8.32 miles, 2851 feet of climbing averaging 6.5%. Time was 1:43:18. Mostly smooth, but I have another rocky climb where I use the same pressures.
The route included pretty rocky sections, and some old school steep rooty, dusty downhills. 21 miles, 3800 feet of climbing in all.

BTW, I use Strava to determine optimum equipment and such by measuring against time so I can bike with my son and not bore him, not because I want to be a Strava god.
I sure wasn't today!
I guess I should add that I only concern myself with climb times. My son can wait on me, on the descents!


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## Suns_PSD (Dec 13, 2013)

angryoldman said:


> Hi, question about tire pressures
> 
> If you are trying to better your own strava climb, 85-90 percent uphill for 40-45 minutes&#8230;
> Do you run the same pressure or more since you don't need the cornering traction as much since you are rolling uphill. As long as you don't spin out due to too much pressure. My rims are around 24 wide and I usually run 18-19 front and 19-20 rear and i weigh around 154.
> ...


Higher air pressure feels faster but on bumpy terrain lower air pressure is faster because the tire moves instead of the bike/ rider on every undulation.
I've done coast down tests at different air pressures on bumpy typical for me terrain and the bike just rolled further and further as I lowered the air pressure down to about 17 psi. At that point I realized that was lower than I could safely run so stopped experimenting. 
Unfortunately I have to run much higher pressure combined with inserts due to my clumsy riding style.

Sent from my SM-G715A using Tapatalk


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## mtnbikeracer76 (Sep 27, 2021)

As a rider weighing in the upper 180's to 190's and eventually over the years in the clydesdale category, I ended up running the rear around 25 psi (hardtail) and the front tire at 22-23psi, depending on terrain. Rockier areas where I ride, I usually bump up the rear to around 28-29 psi just for piece of mind. Seems to work well for my riding style, bike and areas I ride. Haven't blown a tire or bent a rim yet due to low tire psi.


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## MSU Alum (Aug 8, 2009)

Suns_PSD said:


> Higher air pressure feels faster but on bumpy terrain lower air pressure is faster because the tire moves instead of the bike/ rider on every undulation.
> I've done coast down tests at different air pressures on bumpy typical for me terrain and the bike just rolled further and further as I lowered the air pressure down to about 17 psi. At that point I realized that was lower than I could safely run so stopped experimenting.
> Unfortunately I have to run much higher pressure combined with inserts due to my clumsy riding style.
> 
> Sent from my SM-G715A using Tapatalk


I sort of visualize the advantage of lower pressure as levelling out the path of the axle. My climb times are consistently faster (timed) at lower pressures, and I don't ricochet around in techy climbs, which saves a fair amount of energy burned up by core muscles trying to stabilize my movements. Some people (rightly, for their riding) complain about "squirm" which doesn't seem to be a problem for me, and "folding the tire over". I never experienced the second of those until I ran an Assegai up front on really tight bermy trails. I definitely saw it in those conditions though, so I can really see how different people can come to different conclusions on the "tire pressure" question. I still prefer low pressure, though.


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## frdfandc (Sep 5, 2007)

mtnbikeracer76 said:


> As a rider weighing in the upper 180's to 190's and eventually over the years in the clydesdale category, I ended up running the rear around 25 psi (hardtail) and the front tire at 22-23psi, depending on terrain. Rockier areas where I ride, I usually bump up the rear to around 28-29 psi just for piece of mind. Seems to work well for my riding style, bike and areas I ride. Haven't blown a tire or bent a rim yet due to low tire psi.


This is where I'm at. Upper 180's to lower 190's. Rear psi has been in the 24-25 psi range with the front around 22 psi depending on the tire. When I was a clyde rear pressures were up around 28-29. 

I try to start at a reasonable psi then adjust up or down on the trail as the ride progresses. With the rear, I'd ride it lower and lower until i started to get rim strikes. Then I'd add 2-3 psi.


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## BikeRider775 (Dec 1, 2021)

frdfandc said:


> This is where I'm at. Upper 180's to lower 190's. Rear psi has been in the 24-25 psi range with the front around 22 psi depending on the tire. When I was a clyde rear pressures were up around 28-29.
> 
> I try to start at a reasonable psi then adjust up or down on the trail as the ride progresses. With the rear, I'd ride it lower and lower until i started to get rim strikes. Then I'd add 2-3 psi.


Similar here. Around 180 and I have settled on 24-25 psi front and back. No issues with rim strikes or sealant burping.


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## aer0nz (Dec 4, 2010)

185lb heavy rider, fairly bad technique but I do like to ride pretty hard. Ive been doing "marathon" type training (85km+)over the last 12 months or so and a few XCO races.
Originally I started running 19f 21r but my last event was done in nice dry conditions on fairly hardpack trail, 22f 26r and had a great time. 
Ardent race 2.2 on the front and Aspen 2.1 on the rear


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## mrtahiti80 (Nov 6, 2021)

Really depends on a lot of things but I'm 200lbs and running 34psi rear and 26psi front on my Vittoria Syerra's on 30mm ID rims. Could be a little high but at least I'm not worried about breaking wheels.


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## Pedalon2018 (Apr 24, 2018)

Surly29 said:


> As low as possible. I'd start at the lowest recommended pressure (as printed on the tire) and see if you get a pinch flat (small holes on both sides of tube where it contacts the rim). If so, put in a few more psi and run that. If you don't get a pinch flat, run a few psi lower until you do pinch flat.
> 
> Tire pressure is an individual thing. You may also play with the pressure to see how it effects handling, traction, and rolling-resistence.


Tubeless


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## Pedalon2018 (Apr 24, 2018)

No


shiggy said:


> I ride smooth and "light". Started 26 years ago and never owned suspension until 1987. Riding rigid teaches you to pick good lines, be smooth and easy on equipment. Transfer that to suspension and you are even faster. I ride over or around things rather than through them. Trail rider rather than hucker: I jump over things rather than jump off them. I work the bike to keep the terrain from working me.
> 
> My local trails are fairly smooth with some rocks, lots of roots, but I do not really change my tire pressures when I go elsewhere, like Downieville or Gooseberry Mesa. I was running 28/30 psi in 2.2" tires on a hardtail with a 80mm fork at Downieville. Was at the front of the group on the lesser-known trails and slipped to the middle when we reached the main routes (I have little local knowledge of them). No flats, no cuts, no dinged rims.
> 
> ...


Now that’s a pant load……


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## waltaz (Oct 14, 2004)

185 lbs here, in the AZ desert, and run 19 f/23 r on my SS, with Ikon 2.35’s. Was running 16 f/19 r with XR2 2.6’s. Both on Nox Farlow 29mm ID carbon rims.

On my SB115, I run 18 f/22 r with a Dissector 2.4 f and Aggressor 2.3 r, on 30mm ID carbon rims.

I am mindful of my lines, and don’t huck ****.


Sent from my iPhone using Tapatalk


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## Vin829 (Mar 29, 2019)

I’m 170lbs and I’m running 22 rear 20 front on my 2.3 tires. No issues yet


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## pedalinbob (Jan 12, 2004)

MSU Alum said:


> I've run 13 front, 17 rear in Moab for years at my weight of 160. Getting a rim strike hard enough to cut the side wall is pretty impressive, especially for the lighter guys in your group! I've been running a 29x2.3 Mountain King rear and 29x2.4 Trail King front lately on 27 mm rims with Protection and Black Chili. I've used Nobby Nics and DHF/Aggressor combos at that pressure as well with no rim hits.


Kinda zombied this post, but your experience dovetails with something I've noticed about the newer Continental tires: the sidewalls are really stiff, almost plasticky.

I have 2 Race Kings. One is the 18 model, I think. 29x2.3 (or 2.4, don't recall) Protection. Larger casing, more volume than the most recent generation, weepy sidewalls, stiffish sidewalls.
The most recent version is narrower/lower volume, stiffer, and no weeping.

The new Cross King and Trail Kings (29x2.4 protection) are very stiff, and seem to respond better to low pressure. 
I'm only 160lbs, ran them around 18psi (front) and felt like they needed to be even lower to prevent washing out.
We do have fairly twisty trails, and I burped a front tire last year on a high speed turn, so I'm a little cautious.

I think I'll try 15psi...and try not to die. 

Bob


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## Smoomn (Sep 6, 2020)

Don't know if anyone else has recommended it but there this SILCA Professional Tire Pressure Calculator.


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## NordieBoy (Sep 26, 2004)

Smoomn said:


> Don't know if anyone else has recommended it but there this SILCA Professional Tire Pressure Calculator.


For road and gravel.


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## Kiros87 (8 mo ago)

Hi,

coming from old days of 26" tires with tubes I need advice. Having now 29" tubeless with carbon rim I am looking for right tire pressure. I have heard tubeless can run lower pressure compared to old 26"tube. 

I have 176 pounds (80kg), and bike will be used also on single tracks although is xc full suspension. I want to be on safe side keeping those carbon rims straight.

26 psi or 1.8bar is too low?


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## OldMike (Apr 30, 2020)

Kiros87 said:


> Hi,
> 
> coming from old days of 26" tires with tubes I need advice. Having now 29" tubeless with carbon rim I am looking for right tire pressure. I have heard tubeless can run lower pressure compared to old 26"tube.
> 
> ...


If you're railiing corners at 25 mi then that PSI might be required. Otherwise you can get enough support AND a more comfortable ride dropping 3 - 8 PSI, (depending on tire size, terrain, Etc)......IMO of course.

Also, I'm new to CF rims as well and my understanding is that they are either straight or broken, no in-between...


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## Kiros87 (8 mo ago)

Thanks 


OldMike said:


> If you're railiing corners at 25 mi then that PSI might be required. Otherwise you can get enough support AND a more comfortable ride dropping 3 - 8 PSI, (depending on tire size, terrain, Etc)......IMO of course.
> 
> Also, I'm new to CF rims as well and my understanding is that they are either straight or broken, no in-between...


Thanks Mike. I read as well that they stay true. Lucky if they are a bit wobbly, apparently they are easy to true them. 

Would tire inserts protect rims or are they just a fluke?


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## OldMike (Apr 30, 2020)

Kiros87 said:


> Thanks
> 
> 
> Thanks Mike. I read as well that they stay true. Lucky if they are a bit wobbly, apparently they are easy to true them.
> ...


I'm sure others who use tire inserts can confirm, but they should protect the rim against "rim hits". 
I usually adjust my pressure to the riding to avoid rim hits w/o using inserts.


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## Scottie5150 (Mar 10, 2004)

Delete.


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## Aytek (Feb 20, 2021)

wow ! 

after I have seen all the posts here, I am shocked with how much more PSI I was riding on.

I usually ride on 40 PSI (front and rear) for pavement and 38 PSI for trails. I weigh 73 kg.

I will try with reducing it to 30 PSI and see if there are any improvements in my noob riding style.


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## shadowsports (May 10, 2009)

I'm on the cusp lower end of clydes scale. I don't run tubeless.

Lowest I'd probably go 38F / 42R on a 2.3 ~ 2.5 in tire. Traction is important, but you run the risk of pinch flats when your drop your psi super low.


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## J.B. Weld (Aug 13, 2012)

shadowsports said:


> Lowest I'd probably go 38F / 42R on a 2.3 ~ 2.5 in tire.



That's crazy talk. Sketchy at best. Your call of course.


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## Dkayak (12 mo ago)

I weigh 172 lb (78 kg) and run 21f / 22r psi in 29x2.4" tubeless tires on wheels with 30 mm internal width. Lots of traction and a really nice ride too (Trek Top Fuel).


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## NordieBoy (Sep 26, 2004)

Yesterdays short track XC on the Anthem was with 2.3" Mezcal Trails @18f/20r psi.
One of those muddy courses where bigger knobs just means more mud on the bike.
3.5kg of mud with the Mezcals as it was.


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## GlazedHam (Jan 14, 2004)

Silca --yes, the company that make heirloom-quality bicycle pumps --has done some research on this topic, albeit primarily focused on road and gravel riding. The result is this online calculator. For mountain bikes, just pick "single track" and Cat 4 Gravel or Cobbles. There is ample evidence to support the notion that most folks are running waaaaay too much pressure on the road and gravel. Probably, XC racer-types too. I do which they would factor in the "insert" variable as well, but I listened to a podcast from them the indicated inserts don't impact rolling resistance that much. The calculator does aim to prevent you from pinch-flatting so I would bet the do eventually add "insert type" as a factor.

I find it pretty accurate, if you take the time to enter the correct information ...especially total system weight.


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## Dkayak (12 mo ago)

Here are two useful resources. The ENVE table is very easy to use.

How to Optimize Bicycle Tire Pressure | by Randy Runtsch | Bicycle Trekker | Medium 

Tire Pressure - ENVE


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## shadowsports (May 10, 2009)

J.B. Weld said:


> That's crazy talk. Sketchy at best. Your call of course.


Maybe its different for lighter riders or for those running tubeless. I just find more proclivity to flats when you run at lower pressure with tubes. The grip is great though.


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## J.B. Weld (Aug 13, 2012)

shadowsports said:


> Maybe its different for lighter riders or for those running tubeless. I just find more proclivity to flats when you run at lower pressure with tubes. The grip is great though.




30psi on a ~2.4" tire is not low pressure, quite the opposite. 40 is way too unnecessarily high for anyone south of 300# in any conditions ime. Maybe your tire gauge is off?


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## Dkayak (12 mo ago)




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## SB Trails (Sep 14, 2012)

6'2".. 210 lbs.. 25f 28r

As a bigger guy, i hate feeling the tire squirm and burp.. so a bit more air is better for me


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## Eric F (May 25, 2021)

190lbs. 2.25 Schwalbe tubeless on a lightweight hardtail. My riding generally doesn't include a lot of high impact events. Currently, I'm running 25psi front and rear, and it's been all good.


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## GoldenKnightMTB (11 mo ago)

Will lower pressure slow you down?
I have never monitored tire pressure until tonight, now i have a nice tire gauge. 
I am riding 21F, 21R Maxxis DHR IIs 165lbs
Based on how my tire pressure was, it looks like i was riding in the teens.
I am definitely going to experiment going forward.


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## NordieBoy (Sep 26, 2004)

Mezcal Trails @17f/19r 85kg.
Normally running 18f/20r but the Trails have a heavier sidewall.


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## EJ_92606 (Jul 11, 2004)

Another thought, don't assume your pump's gauge is accurate. When mine shows 20lbs it is actually 30. Need a dedicated tire pressure gauge to double check your pump.


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## jochribs (Nov 12, 2009)

EJ_92606 said:


> Another thought, don't assume your pump's gauge is accurate. When mine shows 20lbs it is actually 30. Need a dedicated tire pressure gauge to double check your pump.


Your pump is probably a general high pressure type pump. I've found that the low pressure/higher volume mtn type are closer to what the pressure probably is. My specialized mtb pump reads pretty much dead nuts with my sks digital checker. My Bontrager is way off from both. Haven't used the Bontrager in a road setting in many years (maybe more than a decade?) though as I only have gravel now, and I don't go higher than 35 psi. Would be interesting to pump up some road tires and and check with the sks checker to see if those gauges tell the same story at higher pressures.


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## Dunnigan (9 mo ago)

I’m running in the range of the above chart.
185, 6’1” 
Short travel FS
29x2.35 Ikons on Roval Control SL
21F 23R

XC racing and fast riding, no jumps, and I don’t have problems with rim strikes.
Maybe I could go lower? It’s hard to imagine going under 20 since I grew up thinking higher was better with road tires.
Sure in some situations a higher pressure may roll faster, but on uneven surfaces, or in corners where your limiter is traction, you can’t just optimize for smooth hard surface conditions.


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## BansheeRune (Nov 27, 2011)

Dunnigan said:


> I’m running in the range of the above chart.
> 185, 6’1”
> Short travel FS
> 29x2.35 Ikons on Roval Control SL
> ...


More depends on tires, 27 TPI vs. 60 TPI, vs. 120 TPI for instance. Finer thread tires will roll better at lower PSI than will coarser thread tires. Why? Energy lost to compressing a stiffer casing vs. a supple casing. Higher pressure and terrain feedback (You getting shaken to pieces by tungsten tires) gives an illusion of speed. 

Myths debunked: Higher tire pressure... 

This albeit, is not mountain bike however, sheds some light on what tire pressure can and cannot do for us.

There are times and places for higher pressures to prevent pinches and rim cuts. Tubeless is not immune to rim cuts, burping might replace a pinch flat but air is still missing from inside the tire where we want it to be.


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## NC_Foothills_Rider (11 mo ago)

This tire pressure calculator from Silka is pretty cool. They have some videos explaining their reasoning and the results of their RR tests. The head guy is an ME and knows his stuff pretty good by my reckoning.









SILCA Professional Tire Pressure Calculator


Dial in your tire pressure to get the most comfort, speed, and efficiency out of your ride. If you are looking for the best free marginal gain, click here




silca.cc





To use this you need to measure your tires section widths with calipers, at the widest point.

For my weight and terrain,that calculator returned 18F 19R.

When I ride rockier trails I go to 22F 23R with no problems.

Currently running 29.2.4 Maxxis Dissector front and 29 x 2.25 Rekon rear - both tubeless setups.

The lower pressures work great on smoother trails and I came from the old school "higher pressure is faster".


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## Travolta (Oct 26, 2016)

rule of thumb (its a pun)
grab tire with both hands. put thumbs over each other on tire. push tire to rim.
if you manage to barely touch the rim with the tire the pressure is good.


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