# rear tire pressure - the clyde enigma



## Tappoix (Mar 18, 2004)

I just don't seem able to run anything less than 40 psi in the rear or I will pinch flat while slamming through rock gardens. 

I'm 225 w/o gear, Mavic 819 UST rims, typically a 2.25 to 2.3 tire on the back

tires i've tried (trying to stay below the heavy 900g rear tire weight):

Schwalbe Nobby Nic 2.25
Nokian NBX 2.3
Geax Sturdy 2.25 and Barro Marathon 2.3 (actually, no problems with these)
WTB Motoraptor 2.3

If the pressure goes below 40 psi, the tire begins to see stress lines along the sidewall when i land a jump or run through rocky terrain.

What are you lads running for rear tire pressure?

It's all relative right? I mean, 40 psi shouldn't be some magic number you can't cross, especially given the larger mass of a clyde over it, compared to some 165 lb. dood who can run 32 psi and actually talk about the benefits of lower tire pressure.


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## perttime (Aug 26, 2005)

There's no magic numbers: whatever works is good.
I do not worry about the exact pressure. I only recently got myself a pump with a gauge (pretty inaccurate too). Looks like my eyeball method has put my "2.3" tires (Racing Ralph, Gravity) close to 3 bar / 40 psi.

edit: the front tyre gets a little less pressure, as there is less weight on it. Enough to make it compress about the same as the rear when I just sit on the bike.


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## crisillo (Jul 3, 2004)

yep.. I am about your weight, Tappoix... I also run the tires around 40 psi... and they feel good... given our weight 40 psi might feel like the 32 psi for a lighter dude..


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## Speedub.Nate (Dec 31, 2003)

Sounds about right. I'm around 210 and am pretty particular with my pressures (2 PSI can make a difference!), and I usually ran 40 PSI on my 2.1 26" rear, and 38 PSI on my 2.1 29" rear.

"Lower tire pressure" is relative to the weight it is supporting.


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## bear (Feb 3, 2004)

On the square-edge limestone ledgy and sharp rock gardence of Texas ... at 235# w/o gear and riding a 35# bike ...

- tires smaller than 2.2 on the back needed like 45-50 psi to be safe
- tires 2.25-2.4 seem to be good around 35 psi
- tires 2.5+ seem to be good above 25 psi

BUT, still, infrequent pinch-flats at those pressures from abnormally high-impact situations.

I do *not* focus on riding lightweight tires, so for some samples of tire selection ...

2.2 Geax Sedona
2.2 Kenda Cortez
2.25 or Geax Sturdy
2.24 WTB MotoRaptor
2.4 WTB MotoRaptor
2.35 Kenda Blue Groove
2.35 Kenda Nevegal
2.35 Kenda Small Block 8
2.4 Kenda Cortez
2.5 Kenda Nevegal (current favorite)
2.6 Kenda Kinetics (folding)

I completely walked away from tires < 2.2 for me back in '01 and have never gone back.

I do think I need to branch out some more into other tire lines though. Hard to argue with tires that Just Work And Don't Make Me Complain though.


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## Squash (Jul 20, 2003)

*Yup, it's all relative...*

to your weight, riding style, terrain, and the tires involved. I'm 230, ride pretty much XC/Trail and do just fine on Nevegal 2.1's at 35psi. Not much for rocks round here. But if I know I'm going somewhere with rock gardens etc. I'll jump to a 2.3 Nev at 35 to 40psi. I've also found that going tubeless isn't the "holy grail" allot of folks think that it is either. With Stans I can drop my pressure by an average of 5psi, depending on the tire, with no problems. But much lower than that I start burping tires and dinging rims. So what's the big deal?!?! I have just as much control and traction with a little more pressure and a tube as I do with a Stans set up. And I think the tubed tires with a bit more pressure roll faster for me.

So yeah, it's all relative to weight, tires, terrian, and riding style. No magic formula or mirical product, just what works for you and your set up. :thumbsup:

Good Dirt


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## norm (Feb 20, 2005)

Another Clyde here running around 40psi. Dont give up on tubeless yet. :madman: Try some Ust tires. I thought the same thing when I first tried the Stans setup. After the Stans I bought a couple of Ust tires and loved it. Ust is great for us Clydes.


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## klydesdale (Feb 6, 2005)

norm said:


> Another Clyde here running around 40psi. Dont give up on tubeless yet. :madman: Try some Ust tires. I thought the same thing when I first tried the Stans setup. After the Stans I bought a couple of Ust tires and loved it. Ust is great for us Clydes.


I've had just as much trouble with pinch-flatting UST tires as I have with tubed tires.


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## Sasquatchcycles (Jul 19, 2007)

Convert with Stan's NoTubes to Tubless...end the pinchflat nightmare.


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## ol' Dirt McGert (Mar 21, 2005)

beware, non-tubless content below 

I was the pinch flat king until I switched to those "thorn proof" tubes which are a lot heavier, but when pumped to 40psi allow me to hammer over everything. That's with 2.1 panracer fire xc's. Have yet to have a flat in a season and a half...


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## jeffj (Jan 13, 2004)

I'm in the 'upper 200's' and need to run over 50psi to avoid pinch flats with a 2.10" tire so your numbers sound about right to me. Now I'm running a 2.5" tire and can run much less pressure (closer to 40psi) with the larger volume. However, there is a weight and rolling resistance penalty to pay for the increased traction it provides. It's worth it me, but YMMV.


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## bikemanla (Feb 1, 2006)

*More to think about.........*

I'm 210 and ride rough XC. In Southern California I got tired of thorn flats and changed over to Stan's notubes. Ran 2.0 specialized Roll-x both front and rear at 22lbs in front and 34 lbs in rear. No problems, no flats, better performance.

With my move to Vancouver, BC have changed to 2.35 Nevegals dct to take the nasty large rocks and roots. I am now experimenting with pressures. Rode nasty trails near Banif last week at 22/32 and am trying 20/30 just now. Jury is still out on best pressures.

Added thoughts on Stan's:
1) first time I set up a tire it was hell.....last week no problem at all. There is a learning curve, just as there was with tubes.
2) Rode tires with tubes between the switch over....felt hard,and slow like a solid rubber tire. Back to the Stans and The tires just eat the roots and rocks with a soft smooth ride.
3) Stans works as well on blackberry thorns as it did on desert nasties.


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## PCinSC (Oct 25, 2005)

Tappoix said:


> What are you lads running for rear tire pressure?


I'm pretty much an oddball here, with higher pressure in a heavy, high volume tire. I'm running 40-44psi in a Hutch Octopus UST 2.5" rear on Mavic 823's. This is on my "one bike" which sees techy trail use as well as dedicated DH. For reference, I'm 260lbs plus gear. I have no complaints about its performance.



> It's all relative right? I mean, 40 psi shouldn't be some magic number you can't cross, especially given the larger mass of a clyde over it, compared to some 165 lb. dood who can run 32 psi and actually talk about the benefits of lower tire pressure.


I would think that a heavier rider would see some those same benefits at a higher pressure. That is until the capabilities of the tire are exceeded. I'd be curious to know how heavy a rider tire companies consider when they are designing/manufacturing tires.


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## jeffj (Jan 13, 2004)

PCinSC said:


> I'm pretty much an oddball here, with higher pressure in a heavy, high volume tire. I'm running 40-44psi in a Hutch Octopus UST 2.5" rear on Mavic 823's. This is on my "one bike" which sees techy trail use as well as dedicated DH. For reference, I'm 260lbs plus gear. I have no complaints about its performance.
> 
> I would think that a heavier rider would see some those same benefits at a higher pressure. That is until the capabilities of the tire are exceeded. I'd be curious to know how heavy a rider tire companies consider when they are designing/manufacturing tires.


Another thing to look at is the max pressures rim manufacturers recommend for the various size tires. As Clydes, we're more likely to exceed recommendations on the rims than we are the tires.


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## PCinSC (Oct 25, 2005)

jeffj said:


> Another thing to look at is the max pressures rim manufacturers recommend for the various size tires. As Clydes, we're more likely to exceed recommendations on the rims than we are the tires.


Indeed. Mavic recommends a 44psi max with a 2.5" tire on the 823. I pump 'em up to 50-55psi when installing just to seat the bead (and rode with them at 50psi once just to see how they felt), but as a rule keep them between 40 and 44psi.


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## nachomc (Apr 26, 2006)

Have you considered either going tubeless, or possibly running a rear tire that is a tubeless tire and running it tubed? I was using the Specialized S-works 2Bliss tire (tubed) in the rear and was getting as low as 35 in some pretty technical and rocky sections. I weigh 225 without my gear.


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## Big Pwn (Jul 13, 2007)

I'm 215 and anything less than a 50# rear-end feels mushy in the turns (45# up front). However I use _cheap_ tube tires tho, Continental Explorers w/ _cheap_ Alexrims.


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## crisillo (Jul 3, 2004)

Big Pwn said:


> I'm 215 and anything less than a 50# rear-end feels mushy in the turns (45# up front). However I use _cheap_ tube tires tho, Continental Explorers w/ _cheap_ Alexrims.


that's because of the size... the conti explorers are really small volume tires.. if you moved to something bigger, you would be able to run a bit lower pressure


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## Joules (Oct 12, 2005)

try thinking about it this way: 165# rider with 32psi in his rear tire and say 60% of his weigh on that tire, contact patch is 3.1square inch. A 225# guy, same weight distribution, same tire would need 43psi to get the same contact patch.

you don't run the same spring in your fork as a lesser [weight] rider, do you?


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## brake jack (Dec 28, 2006)

*big tires*

why dont you just use 2.5 tires? it sounds really dumb running 2.1 tires when you weigh 200 lbs. it might be a bit heavier, so what? im 145 lbs with gear, and i run 2.5 tires, still manage to pedal. 
being thicker and larger in volume they eliminate all puncture related issues.

you dont have to be an aggressive rider to use sturdy components. weighing over 200 lbs is more stressful to the bike than a light rider hucking the crap out of it (i witnessed that myself with complete astonishment).


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## Big Pwn (Jul 13, 2007)

crisillo said:


> that's because of the size... the conti explorers are really small volume tires.. if you moved to something bigger, you would be able to run a bit lower pressure


Great suggestion, thanks! I've only seen the bigger tires on AM bikes doing the same XC stuff as I do, so I had it in my mind that a thinner tire was a bonus for XC handling. I'm sure it would help in all my areas of riding, including the "over-compensation issue" we all cling to lol.

Seriously tho, how does the handling characteristics differ for 2.1 & 2.5?


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## crisillo (Jul 3, 2004)

Big Pwn said:


> Great suggestion, thanks! I've only seen the bigger tires on AM bikes doing the same XC stuff as I do, so I had it in my mind that a thinner tire was a bonus for XC handling. I'm sure it would help in all my areas of riding, including the "over-compensation issue" we all cling to lol.
> 
> Seriously tho, how does the handling characteristics differ for 2.1 & 2.5?


well..depending on the tire of course..usually there is a bit more rolling resistance and weight... but traction is improved as well as comfort, since the higher volume tire at a bit lower pressure can conform to the surface while still giving good support..


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## Tappoix (Mar 18, 2004)

WHAM!

Another pinch flat today. CRAP!

psi was 42 when i left the car. I was totally flowing through the trail and rode *firmly* over a square edged rock. (Hey, what do you want me to do i was feeling it! :thumbsup: )

pssssssssssssssssssssssssssssssst.

what a pain in the butt.

i might go back to Geax tires, they have probably been the most dependable UST tires i've tried (i think :skep: )


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## SnowMongoose (Feb 18, 2007)

fwiw, I can't stand to run anything under 40PSI in the rear...
and usually run closer to 50.
freaking hate feeling the rubber get squirmy under me during cornering/riding over stuff.


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## drewactual (Nov 28, 2005)

strange concept this thread holds........(my best yada impression)

I top out at #270, ride Heckler on Cloud Nine rear shock, and Super Minute 20mm qrta fork (fwiw)......

Wheels are Halo Tornado- Tires Hutchinson Spider UST 2.3....Stan'd to hellnback....Stans FR strips over velox tape.....

I tore a sidewall once, but that is the only problem I have ever had running this set-up. No set-up could live through that, so I chalk it up as a anomaly.... I have never cased the wheels, and I do drop up to 3' to flat semi regularly.... and jump often.... here is the thing that I just don't get- I run 28-29psi in those tires....too my knowledge I have never rolled a tire while cornering- certainly not to the point of burping, and have not had a single trail flat with that above exception in well over two years of using it.....to say I am sold on Stans is an understatement.

I just can't grasp the problems you guys have stated and relate to them.... at the risk of peeving a few: when you are as heavy as we are it is easy to blame much of our issues on weight.....but on this issue I bet it is something else- rims/tire compatibility for one- I personally believe Clydes should run wider rims (27mm+) to square the tread more and discourage roll off and bites.... the volume is a no brainer- Clydes shouldn't run anything below 2.2 imo... thicker sidewalls meaning Clydes will benefit from UST tires whether they run them tubeless or not unless they are riding on solid smooth surfaces and in a straight line.... My God man, go tubeless-- and if you do or don't use UST rims, use the Stans...... It makes riding a lot more enjoyable as you don't have to worry about it anymore..... 

hmmmm- better traction at lower psi, eliminate snakebites, clog up pesky thorn punctures without even knowing they are there, durability and dependability- vs the exact opposite of what I just said.....cost? how many tubes do you go through in a year? How many rim welds have you broke because of high psi? How often do you have to stop and tear a tire off the rim and repair the tube? frustration alone it is worth it....

This has been an advertisement.....Mr Stan please make check payable to DrewActual...


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## Acme54321 (Oct 8, 2003)

I usually run 35-40psi in 2.3 Weirwolfs, 230lbs. Haven't pinch flatted in years. 4 foot drops, rocks, climbing stairs, no problems.


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## Paul1977 (Aug 9, 2007)

I used to get pinch flats when I first started riding and I wasnt smooth. In the last few years I havent had pinch flats since I have changed to tires with a beefy sidewall.

I use a Michelin Comp16 2.2 on the rear of my bike and I cant pinch flat it. Its mounted on a Sun Singletrack rim. I use a standard 2.1 tube to keep the weight down and run it at 30psi. Im a six foot four clydesdale so im no lightweight.


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## bongo_x (Aug 20, 2006)

I'm 230-240 and I think I've only pinch flatted once in my life, riding since '89. I tend to run higher pressure though. I'm not sure how much since I don't really check it, I just hate it too low. it makes it too much work and feels mushy.

bb


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## Dwight Moody (Jan 10, 2004)

*Downhill tubes*

I run downhill tubes and don't have an issue with pinchflats. When I went from rigid to hardtail, I was pinchflatting all the time because I'd kicked up my speed a couple notches and my smoothness not one bit. When I finally got downhill tubes my problems were solved. I don't check my pressure regularly, but I'm guessing (based on the old pinch test) that it's about 45psi.


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## Ken in KC (Jan 12, 2004)

*Flogging Trigger....*

Ever feel like a broken record?

Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.

Tubeless? Whatever. You'll still pinch unless you run * higher volume * tires. Unless you run tubeless for flat protection from thorns, there's not a huge advantage in tubeless for big guys. Higher volume is where it's at.

The general understanding here is that you still have to have some degree of skill. Casing your rear wheel in to a rock will still trash your wheel and cause a flat.

Now before you get all uppity and suggest that I don't know what I'm talking about, please consider the trails I ride. Kansas City is nothing but millions of years of rivers exposing limstone ledges and glacial till. In other words, rocks. Lots and lots of rocks.

Higher volume tires for Clydes. Man law?


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## Random Drivel (Oct 20, 2006)

Ken in KC said:


> Ever feel like a broken record?
> 
> Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.


Well, the only reason I can think of running a lower volume tire on the rear of my giant man-carcass bike is because lower volume tires sometimes have less flexy sidewalls. The Nevegal comes to mind here, the 2.1 was less flexy than the 2.35 on the rear of my Flux.

But I agree with your comment; I run 2.35 Rampages (29ers) f/b at 30 psi and have not pinch flatted in over 3 months. They are tremendously awesome when mated to RhynoLites or any wide rim.

Oh, and forget the boyracer lightweight tubes--use a real man tube and pinch flats are a thing of the past . .


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## Tappoix (Mar 18, 2004)

Ken in KC said:


> Ever feel like a broken record?
> 
> Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.
> 
> ...


Ken

Totally agreed. I learned that lesson and never run less than 2.25. And the part about casing....OK, maybe I'm a bit guilty. But only a bit!

But your part about larger tires/lower pressures.....i'm having to go 40+psi to avoid the tire rolling when I land jumps and bang through rock gardens.....I don't call that lower pressure. But that is the point of the thread....that it's all relative, eh?

Now, high volume, beefier sidewalls, and a reasonable weight.....well, the "reasonable" part is the relative part of that equation!

Tell me the tires you like to run, good sir.


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## dwnhlldav (Feb 2, 2006)

I'm 250 in my underoos.

2 things, I just can't under stand why a clyde would run anything less then a 2.25 and even that is little.

Up until recently I ran 2.5 Nevegal folding beads for about a year and a half and didn't have a single flat. Pressure was anywhere from 25 to 35 depending on when the last time I pumped them up was. Never had them roll on the rim and they never felt squirly. And PA has rocks.

I just switchback to a pair of 2.35 Nokian Gazzallodi (sp?) Core folding bead. I only switch back to these because the Nevegals were rubbing the chain stays and fork of my current ride. Previously I experimented with these tires and had them down to about 23psi before they started to roll. I generally run them at 35psi. Two weeks ago I had them down to 30 and pinch flatted but it was a hard square hit That I didn't see coming so I had no finesse.


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## Ken in KC (Jan 12, 2004)

*WTB Motoraptor 2.4....*



Tappoix said:


> Ken
> 
> Totally agreed. I learned that lesson and never run less than 2.25. And the part about casing....OK, maybe I'm a bit guilty. But only a bit!
> 
> ...


WTB Motoraptor 2.4. I've been running them for several years. They don't do one thing *great* but they do everything really, really well. They're the best all trail, all condition tires that I've ridden. For clarity: They're the best *for me*. Someone else might hate them.


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## carbuncle (Dec 9, 2005)

While I've been freeriding I have ranged between 215# and 255#, currently at about 230#. I have never once given a thought to tire pressure as regards my weight, and run 30 psi for the Shore or anything with wet, rooty and rocky terrain and maximum 35 psi for Whistler or similar dry, fast terrain. I have used 2.35 Maxxis High Rollers and Minions and 2.5 Tioga DH Pro and Kenda Nevegal tires. For street riding I have run Tioga City Slickers on my commuter at 80 psi, and Kenda K-rads and Maxxis Holy Rollers at 40-60psi depending on the day and the ride. I have taco'd one wheel, an Azonic Outlaw, and that was about six weeks ago in a freak occurance at Whistler, and have experienced 0 pinch flats and only regular wear and tear on wheelsets (except on the Azonic front wheel, which I am convinced is a complete POS: I'm rebuilding the set with Mavic EX 729s, DT spokes and the AZO hubs next month). Wheelsets have mostly been OEM, with a mix of Shimano, Formula and no-name hubs and WTB or low-end Mavic rims, and abuse has been dished out liberally on the Shore, Whistler, Blackrock in Oregon, local trails, etc. I'm thinking that with high volume tires, decent tubes (no butyl or similar lightweight shite) and a modicum of riding finess that even a fairly good-sized individual such as myself can get away with just making sure that your wheels are tensioned and maintained by a professional (something I have done to ALL of my wheels) and running a standard range of pressure suited to the conditions. 
But that's just my experience.


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## Qfactor03 (Dec 8, 2005)

On a recent trip to Ellijay, GA (home of some very high speed, rocky descents) I was able to run 38 psi in a Maxxis Ignitor (29er) without problems on my ti hard tail. I have also run 35 psi in a Panaracer Rampage on the back of a rigid single speed successfully, but it is a very large tire for a 2.35. At my weight of 265, I don't see a practical reason to run any lower than the mid-thirties in the rear and typically run 40 psi on my local trails.


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## Tappoix (Mar 18, 2004)

ok guys, you're not going to believe it......another flat

i did a 2.4 hour ride last week and was just hammering the whole time, the tire pressure was probably 45psi and it held the whole time.

today, with 10 minutes left on a 2 hour ride, WHOOOOOOSH, on a smooth piece of trail, the nut fell off the valve stem and there was a hole in the tube and the rear totally deflated. In fact, the valve stem retreated completely into the rim (819s) adn a Nokian NBX 2.3

WTF is going on here, this is getting ridonkulous!

MeanTodd at Webcyclery built my rear wheel, I'm going to have him look at it. do I really have to get some 900g tire? fack!


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## Vhom (May 23, 2007)

I know it's kind of odd, I was running close to 40 PSI on my 2.1 Kenda BlueGrove and getting lots of pinch flats. I then tried running around 32-35 psi and had none since I've lower the psi in the tires. I know it sounds crazy, but give it a try.


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## CaveGiant (Aug 21, 2007)

One way of looking at it is you want to keep the rear weight down to keep your speed.
Well these flats are slowing you down and do those lost seconds really mean that much out of a race.

If you flat get a bigger tire and keep getting bigger until you can finish a ride.

One thing though, is I ride Maxxis ignitor 2.1 LUST on a mavic XC717 with Joe's tubeless (stan knock off, didn't even relise till I got home) and the rear pressure is only at 20 at the moment.

Now not sure how hard I ride compared to you guys but took a 30mph off road descent where no-one else was doing above 15 on a HT and broke my rear hub by the time I got to the bottom. fun as anything and definatly worth the £10 hub repair.
Havn't damaged the rim or lost pressure in the tire. I am also learning drop offs but nothing bigger than 1-2' at the moment, 240lbs


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## CaveGiant (Aug 21, 2007)

I should add a few weeks back I hit a rock so hard on the trail it broke my rear drop out.
Unsurprisngly I hit dirt hard.
Cleat ripped off the bottom of my peddle, seatpost bent, hub came apart, disk rotor bent and rear pads torn. Tire didn't lose pressure and rim fine.

£586 worth of repairs, or as I see it, a £50 excess!


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## Tappoix (Mar 18, 2004)

I've been running a WTB Stout 2.3 with about 40 psi on there....it's held just fine for a 850g tire.....wouldn't hold tubeless with stans, but fine with a tire

a Hutch Barracuda 2.3 held fine tubeless, but the Stout rolls better (but the 'cuda rails turns!)


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## Ken in KC (Jan 12, 2004)

*I'm confused....*



Tappoix said:


> ok guys, you're not going to believe it......another flat
> 
> i did a 2.4 hour ride last week and was just hammering the whole time, the tire pressure was probably 45psi and it held the whole time.
> 
> ...


Flats are part of mountain biking. Are you expecting to never flat? The hole in your tube was located where? On the outside of the tube (toward the tire? On the inside of the tube (toward the rim)? Two holes? One hole? Round hole or an elongated rip? Is it possible that you have a thorn in your tire that's causing you to flat? Have you run your hand inside your tire to feel for something sharp imbedded in your tire?

The stem will fall inside the rim when the tire goes flat. That's normal.


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## CaveGiant (Aug 21, 2007)

Not relevant, but I actually meant ot say the cleat ripped off my shoe...far more unusual than off the peddle, they are supposed to do that


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## clarkgriswald (Dec 19, 2003)

*On my current XC bike*

I run 2.1 Schwable Nobby Nics and Little Alberts at about 35-40 PSI. Rims are Mavic 717s. Never pinch flatted and I weigh 250+ with gear. Torn sidewall once. Since it's an XC bike the trails are realativly smooth and when I come to a rock garden I slow down and pick my way through.

On my AM/ Six Inch travel bike I run Big Betty (2.4s) on the front and a Fat Albert (2.3s I think) on the rear both about 35-40 PSI. Rims are 819s. Never pinch flatted. Rock Gardens are taken at speed with an eye for square edged rocks, I try to avoid slamming into them or unweight a little bit to lesson the impact.

If you want to blast your way through stuff; large volume, 35-40 PSI and a little finese would go a long way. It seems to work for me.

Over the years my speed has gone up pinch flats have gone down. Seems like the first year or two of riding I pinch flatted every ride. Tires have improved since the early 90's, but so has my smoothness.

One more thought; is this always happening at speed and over a stretch of rough stuff? Your shock might be packing up and need a high speed rebound adjustment?


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## utabintarbo (Jun 29, 2007)

Would it not make sense to adjust the pressure to achieve a nearly full tire contact patch, add a few pounds, then adjust? One would think that any specific bike/rider combination will require different actual pressures.

Apologies if this is asked & answered.


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## PCinSC (Oct 25, 2005)

utabintarbo said:


> Would it not make sense to adjust the pressure to achieve a nearly full tire contact patch, add a few pounds, then adjust? One would think that any specific bike/rider combination will require different actual pressures.


I think I agree with this, but I have a noob question. What qualifies as "full tire contact patch"?


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## utabintarbo (Jun 29, 2007)

PCinSC said:


> I think I agree with this, but I have a noob question. What qualifies as "full tire contact patch"?


One in which most, if not all, of the little nubblies of the tread touch the ground? Can possibly be checke by running over a wet spot, for instance.

Disclaimer: I am a n00b myself. YMMV.


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## clarkgriswald (Dec 19, 2003)

*Depends on the tire.*

Tires of the same size will have different shapes of carcass and tread. Think sport bike motorcycle tire vs. a dragster slick. Extreme expamle but a good one, I think.

The Motor Raptor has a more rounded carcass that is really nice for quick left to right leaning transitions. Some of the Kenda's are more square and offer more stable upright ride.

So if you understand the tire you might be able to get the correct pressure for that tire by looking at the contact patch. But then you'd have to account for soil inconsistency. Muddy, damp, dry etc. Dirt is not all the same. So even more variables to throw into the mix.


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## Ken in KC (Jan 12, 2004)

*^^^Good Advice^^^*



clarkgriswald said:


> Tires of the same size will have different shapes of carcass and tread. Think sport bike motorcycle tire vs. a dragster slick. Extreme expamle but a good one, I think.
> 
> The Motor Raptor has a more rounded carcass that is really nice for quick left to right leaning transitions. Some of the Kenda's are more square and offer more stable upright ride.
> 
> So if you understand the tire you might be able to get the correct pressure for that tire by looking at the contact patch. But then you'd have to account for soil inconsistency. Muddy, damp, dry etc. Dirt is not all the same. So even more variables to throw into the mix.


I prefer Moto Raptors (2.4) for dirt and Kenda something or others (2.3) for urban. The Kenda's wash out too much in dirt for my liking and the Motos wash out too much on pavement.

Another thing to consider is that there's no volume standard to speak of. A Continental 2.3 is smaller than a Kenda 2.1.


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## bikemanla (Feb 1, 2006)

Update - - - after testing many lbs combos have ended up at...are you ready?......17 lbs in the front and 31 lbs in the rear. This works great for me in extreme XC riding here on the North Shore. I ride with about 35-65 weight distributation so I can easily jump logs and rocks!


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## crisillo (Jul 3, 2004)

Ken in KC said:


> Another thing to consider is that there's no volume standard to speak of. A Continental 2.3 is smaller than a Kenda 2.1.


agreed... however it seems that Conti has calibrated their measuring scales with the new King series (Mountain King, Race King, etc)


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## bigdudecycling (Aug 16, 2007)

Would anyone have a solid suggestion for what tires and pressures to run for XC riding in the Arizona desert? My weight runs between 210 and 220, and my riding varies between smooth desert cross country (McDowell) to sometimes gnarly south mountain (rocks/cactus) to T-100. 
Any general thoughts? i've finally realized all my past tire choices have been bad and have been unfortunately driven by small guy guidance....


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## mikepro (Sep 11, 2007)

Well, since I just bought a bike about a week ago, I've been going through this same conundrum. I'm riding a Gary Fisher X-cal 29er, and I weigh about 285lbs. It has a Bontrager Jones XC 2.2 rear, and the same tire but in a 2.25 front. I had some issues at first with a faulty gauge pump, so I wasn't sure what I was running at first. (In fact, I ended up rolling the front off the rim, because I think I was only at like 20 psi).

Anyways, I was running the rear at about 40, and the front a bit less. To me, the bike just felt a bit squirrely in corners. I wasn't sure if I should lower pressure, or raise pressure in this situation for better cornering. Anyways, today I tried it with 50 rear, 40 front. _Remember, these are 29" tires, so I thought this seemed quite high. _

Well, it seemed to handle much better in the corners, although it was a bit bumpier. Halfway through my ride, I let a bit of air out (no gauge, but maybe a few psi). It smoothed things out a bit, and still seemed to handle ok. I think I just need to experiment to find my sweet spot, but I am kind of surprised that on these big wheels it seems like that will be above 40 psi rear.

What I really need to do is drive up to where I ride and bring my floor pump and gauge, so I can do multiple runs at different pressures and get a feel for how the handling changes. Maybe go from like 35-50 psi in 2 psi increments.


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## EDDIE JONES (Mar 26, 2005)

I weigh 285lbs before gear and have run tires like the Python Airlight with no flats ever. I generally run about 38psi on the rear and 35psi on the front. I have run IRC Kujo's all the way into the mid 20psi range. Again, no problems. Right now I ride a 29er SS and change the tires all the time and have yet to pinch flat. However, I do try to lift the front and unweight the rear when needed and stand when I have to. But sometimes, when an obstacle comes up by surpise, you can't always do this. So far (knock on wood) my riding style seems to be working. I have never rolled a tire over. I have seen guys much lighter than myself get flats on every ride. They never check their pressure and run right into things with all of the finesse of a bull in a china shop. Then they complain about their tires or tubes. MTBR's review section is full of these ignoramuses complaining about bad tires. They should be talking about their own stupidity. I check my pressure before every ride. I also know by thumb pressure about where they need to be. If you do this your pich flats would be reduced to none........nada........zilch............zero, in no time.


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## mikepro (Sep 11, 2007)

hey Eddie, we seem to have a similar build, and both ride 29's. It's interesting that you run a pressure so much lower than what felt good to me (38 psi vs. 50 psi for my last run). I'm gonna try a run at your pressures and see how it feels. It's kind of surprising that different tires would be that different. Then again, maybe I am just so used to my road tires at 120psi, that I'm biased towards liking a higher pressure in my mtb tires.


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## utabintarbo (Jun 29, 2007)

I, too, run 29" tires and weigh ~270. I have WTB Exiwolfs at ~45 psi. Well, at least I start out there. I have run them down to the 30psi range, at which point they got a bit squirrelly. On known trails I tend to be a lot better in line choice, but when hitting a new track, I am that bull referred to above. Either way, I have never flatted. IMHO, better to have a little too much air than too little. Though my back disagrees....


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## EDDIE JONES (Mar 26, 2005)

mikepro said:


> hey Eddie, we seem to have a similar build, and both ride 29's. It's interesting that you run a pressure so much lower than what felt good to me (38 psi vs. 50 psi for my last run). I'm gonna try a run at your pressures and see how it feels. It's kind of surprising that different tires would be that different. Then again, maybe I am just so used to my road tires at 120psi, that I'm biased towards liking a higher pressure in my mtb tires.


I think those little hard rubber road tires have made you immune to the trail I have tried to run pressures in the mid 40's-and higher but the bike bounced all over the place and the ride was harsh. When I found my "sweet spot" it was wonderful. I had to ignore the fact that I am a clyde and I was going to pinch flat unless I ran the higher pressures. So far, no problems. But that is not to say that it won't happen. It just hasn't yet. When it does, I will bump the pressure a little bit.


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## edouble (Apr 16, 2004)

*I am 6 ft 2in...*

and go 250lbs bucket naked. I have ridden my 29ers and 26ers for over 2yrs now with stans and not had a single pinch flat. I run 38psi front 40psi rear on all my tires and have found these #'s to be a good compromise of grip and pinch flat protection.


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## bongo_x (Aug 20, 2006)

I've been riding since '89 but you learn something new all the time. I'm about 230-240 and ride cross country. I've never cared that much about what tires I rode since there wasn't a huge difference to me. I've always ridden with pressure in the mid 40's on about 1.9 to 2.1's. 

It never occurred to me to try bigger tires since I only ride XC on a hardtail, I thought big tires were for downhillers. Because of comments on this forum I tried some bigger tires, 2.3 or 2.4's, I can't remember right now because the bike's outside, but they're HUGE compared to what I had. 

I love it. I'm really surprised at how much better it is. Everything about it is better and I think it works well with the higher pressure. I wish I had known this earlier. Big tires for big guys and girls, makes sense.

bb


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## bikemanla (Feb 1, 2006)

Just a thought.....long, long ago I heard the same thing being said about those funny radial tires. You still running those hard, high pressure cross-bias tires on your car-truck-race car-suv? 

Get with the program........it's about performance not feel.


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