# Rockshox Reba fork question?



## Kiwi_GR_Biker (Nov 17, 2012)

How often should you need to check and or pump up the air shock?

I had a new Reba installed on my bike just a few weeks ago and the guy in the shop inflated it to 120 psi for my weight which is approx 80 kgs or 180 lbs. I''ve been riding reasonably frequently but not especially hard riding. Anyway today I bought a shock pump and the gauge showed the pressure to be down around the 80-90 psi level. Is that a normal loss of pressure in such a short time?

Is it something you should check frequently like weekly, fortnightly, monthly?

I didn't own a shock pump when the LBS installed it but the guy said I should get two months use before needing to pump it up again. If it was indeed inflated to 120psi I'm just a bit surprised it's lost about 30-40 psi so quickly?


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## Shibby (Jan 13, 2004)

When you attach the pump to the shock, some air exits the shock's air chamber to fill the pump hose. If you inflate the shock, detach the pump, then attach it again immediately afterwards, you'll probably see a big drop in pressure which would mean your not leaking. Shock air chambers are pretty small, so that bit of air can make a big difference in the pressure reading.

A frequent follow-up question is whether the air you hear hissing when you detach the pump hose is air escaping from the shock. It's not, it's escaping from the hose - most pumps have a mechanism to prevent air leaving the shock when you detach the hose.

On my dual air Reba, I'm refilling every couple of months which seems to be fine.


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## zebrahum (Jun 29, 2005)

I find that you usually lose between 5 and 15 psi depending on fork or shock when you attach the pump. 30-40 psi seems like too much. I would pump it up to whatever level you should be at (you did work that out, didn't you?) and then check it again in a couple of weeks. I also tend to check air pressures about once every couple months, usually just long enough that I can't remember what I pumped them to the last time.


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## Burt4x4 (Feb 21, 2013)

Question ~ If your air pressure gets low wouldn't you be able to tell by amount of movement you get when you sit on the bike..what did you call that..pre-sag you know the 20-25% movement you get by just getting on the bike..sorry brainfart on the term that is used...


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## kapusta (Jan 17, 2004)

This^^^

Also, different shock pumps may differ from each other in pressure readings. So the 30-40 psi drop could be partially due to differences in the pressure gauges on your pump and the shops pump.

I would pump the shock up to whatever pressure you want to try. Disconnect then re-connect the shock pump and see how much it drops. Do this a few times to be sure. Now you know how much pressure drop is due to re-attachment.


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## attaboy (Apr 4, 2008)

I check before each ride. Almost always needs a few pumps in the negative air side. I ride technical trails and I think that cycling the shock more frequently is a factor. Also, notice when temps drop significantly (40 degrees) between fills that the shock looses more air.


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## zebrahum (Jun 29, 2005)

attaboy said:


> I check before each ride. Almost always needs a few pumps in the negative air side. I ride technical trails and I think that cycling the shock more frequently is a factor. Also, notice when temps drop significantly (40 degrees) between fills that the shock looses more air.


Sounds like you need to rebuild your fork. No way a fork or shock should loose air that quickly. Actually, if you have a shrader valve core tool, check the valve core on your negative side, it might be loose.


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## Kiwi_GR_Biker (Nov 17, 2012)

Shibby said:


> When you attach the pump to the shock, some air exits the shock's air chamber to fill the pump hose. If you inflate the shock, detach the pump, then attach it again immediately afterwards, you'll probably see a big drop in pressure which would mean your not leaking. Shock air chambers are pretty small, so that bit of air can make a big difference in the pressure reading.
> 
> A frequent follow-up question is whether the air you hear hissing when you detach the pump hose is air escaping from the shock. It's not, it's escaping from the hose - *most pumps have a mechanism to prevent air leaving the shock when you detach the hose.*
> 
> On my dual air Reba, I'm refilling every couple of months which seems to be fine.


Thanks I have figured this out now. :thumbsup:

Maybe you're right and I simply let out a bunch of air when I screwed the pump on the first time. Anyway inflated the fork to 120 psi tonight and went out for a ride but to be honest the fork felt too firm.

Can someone please explain the adjustability with this fork? The air pressure is self explanatory. The Motion Control (floodgates) adjustment just seems to affect the amount of give in the lockout. The rebound adjustment you turn it towards the hare (faster) or the turtle (slower). What type of riding is the faster/slower setting appropriate for?

I have been riding mostly easy trails but have some buddies who will be taking me out on some tougher rides. Just wondering what setting is more appropriate for the tougher trails.

Thanks for all the tips in advance.


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## DiRt DeViL (Dec 24, 2003)

On every ride is a bit overkill but a sanity check every month or so isn't a bad idea, I haven't checked mine in months and is fine.


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## zebrahum (Jun 29, 2005)

Kiwi_GR_Biker said:


> Thanks I have figured this out now. :thumbsup:
> 
> Maybe you're right and I simply let out a bunch of air when I screwed the pump on the first time. Anyway inflated the fork to 120 psi tonight and went out for a ride but to be honest the fork felt too firm.
> 
> ...


There are nearly infinite resources on setting up forks across the internet, with a very quick google search I found these: 
Setting up your Reba

Rockshox_SID_Motion_Control - YouTube

Those should be able to help you get the thing dialed in.

Really, everybody is different and one setting doesn't work for all people. I want my fork active so my LSC is moderate and my HSC is too while my rebound is fairly fast. No so fast that the bike pops up when it's unweighted, but fast enough that the fork doesn't pack up under stutter bump braking. Playing with your adjusters, knowing what they all do, and adjusting while riding will all help you get your suspension where you want it to be. When in doubt, take it to someone who can help you; 15 minutes at your LBS can prevent years of thinking you got your fork in the right spot when you actually weren't even close.


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## Kiwi_GR_Biker (Nov 17, 2012)

zebrahum said:


> There are nearly infinite resources on setting up forks across the internet, with a very quick google search I found these:
> Setting up your Reba
> 
> Rockshox_SID_Motion_Control - YouTube
> ...


Thanks mate. :thumbsup:

That first article is very clear. I have been searching but couldn't really find anything as clear and concise as that and the Sram site just seems to offer tech advise on the assembly/installation and maintenance of the fork. When I tried to read up on motion control all it offered was some BS about 'walking on the moon' or some such marketing nonsense. Anyway thanks again. That is very clear. Time to go and tinker. 

Just one other question about cleaning and maintenance. I tried reading the noob guide but I think it ended up with two guys arguing over the best cleaning method. LOL Do you guys use a lubricant on the fork stanchions? The Sram site recommends it but but my LBS just recommends keeping it clean.

Just wondering what you think and what products you use?


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## kapusta (Jan 17, 2004)

Kiwi_GR_Biker said:


> The Motion Control (floodgates) adjustment just seems to affect the amount of give in the lockout.


Actually, it does effects fork even when it is "unlocked". The floodgate acts as a blow-off of the compression damper. When you lock out the fork, the damper is closed, so the fork can't move. The Floodgate adjustment adjusts the force needed to over-ride the damper and let fluid flow through (and the fork move). However, even when unlocked, at high shaft speeds pressure still can build up at the compression damper, and you can get what is known as "spiking", which can make the fork feel harsh on high speed hits. With a very light floodgate setting, the floodgate can respond to this pressure and open up and over-ride the compression damper and avoid this spiking.

You will never be able to detect any of this standing around pushing up and down on the fork (you can't push down fast enough), it's something that is really only noticed when riding fast over the rough stuff.

Long story short, a very light floodgate setting can help on very high speed hits. As a result, on my Pike I end up running the Floodgate so light that it is virtually useless as a lockout.


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## moronm (Mar 23, 2011)

dont forget temperature can have a large impact on pressure, if at the bike shop they filled it at room temperature 25oC and you then leave it in your garage which this time a year could still be quite cool (0-5oC), you will actually read a lower pressure, even if there is no air leaking.


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## zebrahum (Jun 29, 2005)

Kiwi_GR_Biker said:


> Just one other question about cleaning and maintenance. I tried reading the noob guide but I think it ended up with two guys arguing over the best cleaning method. LOL Do you guys use a lubricant on the fork stanchions? The Sram site recommends it but but my LBS just recommends keeping it clean.
> 
> Just wondering what you think and what products you use?


Well unless your LBS manufactures your fork, I would stick with what Sram says. I try to clean the stanchions and dust seals every ride and I drip a little bit of T-9 on the stanchions and cycle then clean about once a month. Don't forget the routine fork service like oil changes and dust seal changes.


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## Kiwi_GR_Biker (Nov 17, 2012)

kapusta said:


> Actually, it does effects fork even when it is "unlocked". The floodgate acts as a blow-off of the compression damper. When you lock out the fork, the damper is closed, so the fork can't move. The Floodgate adjustment adjusts the force needed to over-ride the damper and let fluid flow through (and the fork move). However, even when unlocked, at high shaft speeds pressure still can build up at the compression damper, and you can get what is known as "spiking", which can make the fork feel harsh on high speed hits. With a very light floodgate setting, the floodgate can respond to this pressure and open up and over-ride the compression damper and avoid this spiking.
> 
> You will never be able to detect any of this standing around pushing up and down on the fork (you can't push down fast enough), it's something that is really only noticed when riding fast over the rough stuff.
> 
> Long story short, *a very light floodgate setting can help on very high speed hits. As a result, on my Pike I end up running the Floodgate so light that it is virtually useless as a lockout*.


Thanks. Very useful info. Through playing around and running it on a light setting I also noticed the lockout was not very effective.


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## Kiwi_GR_Biker (Nov 17, 2012)

moronm said:


> dont forget temperature can have a large impact on pressure, if at the bike shop they filled it at room temperature 25oC and you then leave it in your garage which this time a year could still be quite cool (0-5oC), you will actually read a lower pressure, even if there is no air leaking.


I'm in NZ and we're experiencing pretty balmy autumn temperatures so don't think that is the problem on this occasion.


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## jjaguar (Oct 6, 2011)

A systematic way to dial in your suspension is a technique called bracketing. It takes a little time, but your bike will be dialed in perfectly for your riding style and local conditions.

Start by turning the adjuster all the way to the minimum and take a test ride on a section of your regular trail to see how that feels. Then, set it to maximum and ride the same section. Now you know what the two extremes feel like. Next, set the adjustment to the middle, ride the test trail again, and decide if you would like more or less. Split the difference, test again, and repeat until you settle on the setting that feels best.

For example, lets say some adjustment has a knob with 20 clicks. After trying the extremes, set to 10 clicks. Lets say after that you want more, so turn to 15 clicks. Okay, that's a little too much so back off to 12 or 13, and so on.

Work on one parameter at a time, otherwise it's hard to tell what is doing what. Setting everything to factory recommended settings usually will give you a reasonable starting point at first, too.


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## Kiwi_GR_Biker (Nov 17, 2012)

jjaguar said:


> A systematic way to dial in your suspension is a technique called bracketing. It takes a little time, but your bike will be dialed in perfectly for your riding style and local conditions.
> 
> Start by turning the adjuster all the way to the minimum and take a test ride on a section of your regular trail to see how that feels. Then, set it to maximum and ride the same section. Now you know what the two extremes feel like. Next, set the adjustment to the middle, ride the test trail again, and decide if you would like more or less. Split the difference, test again, and repeat until you settle on the setting that feels best.
> 
> ...


Thanks. Great advice. I had set most things to a mid setting or approximately 10 clicks in your example and that seemed to work pretty good. I can try and fine tune it from there now that I have a better understanding of what the different adjusters do.

Using the 60% weight setting as the starting point means setting the fork at about 105-110 psi. Starting at 120 may have been a tad high.


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