# Rockshox Reba Race



## smithy92 (16 Jun 2011)

Hi All, 

I've recently invested in a new mtb, which came with the rockshox reba race dual air 100mm fork.

Can anyone explain (or point me to a guide), what effects the rebound, compression, floodgate and positoce/negative air pressure will have?

Thanks in advance.


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## Cubist (16 Jun 2011)

I'll do my best.

You need to put air into the fork via the schrader valve on the top of the left fork leg. There will be an approximate guide on the leg itself or in the manual as to how much pressure you need to put in. . If you put as much air in as the manual suggests you will have a pretty stiff fork that is unlikely to reach the end of its travel on most rides. The amount of air pressure in the fork affects the amount that the fork will compress when you go over a bump or down a step. 

You can find the best setting for the fork by trial and error.The first stage is setting the sag. This is the amount of travel that the fork will move when unlocked, with just the weight of the rider on it. Most people say 25 to 30 percent of the full travel of the fork, but personally I like to run mine a bit plusher at 33%. 

Get a cable tie and tie it round the fork stanchion (the shiny bit that moves in and out of the fork lower) and push it down to the seal. Now, being careful not to bounce, get onto the bike and stand on the pedals in the "attack" position. It'll help if you are wearing your normal riding clobber. Get off the bike and look at where the cable tie is. It should have been pushed up the stanchion. If it is higher than 25 to 30 percent, you have too much sag, and need to put some more air in. If less than 25 percent you need to let some air out. 

Make a note of how much pressure you have in to get the desired sag. 

Once you have set the sag leave the cable tie in place, you'll need it for feedback later on. 


You now have positive air pressure in the air spring, and the negative lower chamber will be balanced at the same pressure. This negative chamber is designed to fine tune the spring compression rate. It can only really be found by experience and trial and error. If you find that the fork is blowing all the way through its travel on some bumps but not responding to little ones ie all or nothing, try tweaking the rate by reducing that lower negative pressure. Trial and error is the key. You adjust the lower spring pressure via the schrader valve at the bottom of the left hand fork leg. 

Now move onto the right hand fork leg. On it you have the fork lockout (it may be a remote lever to the bars or a manual lever). This is simply a means to stop the fork compressing when you don't want it to, such as on the flat or climbing. Unlocked forks can "bob" when you pedal and waste energy which could otherwise be used for forward motion. 

You also have a blowout gate adjuster. This is designed to save the seals and internals (and the rider) from moderate to big hits when the forks are locked. If you like it is a safety valve for when you unexpectedly hit a pothole when you have locked the fork. The adjuster has a plus and minus sign on it, which increases or decreases the energy needed to blowout. 

On the bottom of the right fork leg is the rebound adjuster. It affects the speed at which the fork returns to normal after being compressed. This damping effect means that the fork responds to bumps and drops in a controlled fashion. Too slow, and it won't decompress quickly enough to hit eh next bump, and too fast and it will bounce off an obstacle possibly pitching you off in the process! To set this adjustment ride the bike off a kerb and get someone to watch how the fork behaves. If it returns smoothly and quickly to normal without bouncing it's just right. If it bounces turn the adjuster towards the tortoise pictogram, and if it returns sluggishly, turn the adjuster towards the hare.

Now ride the bike. Remember the cable tie on the stanchion? Push it all the way down at the start of the ride, and use it to check how much travel the fork is using. I sometimes check it after the first drop or whatever. If the fork has used all of its travel without topping out (you'll hear it bang on a drop or bump) then it's set just right. If it uses less than 90 odd -percent of its travel you have it set too stiff and need to let a bit of air out. 

By keeping a record of how much travel each ride uses, you'll be able to guesstimate whether or not you need to put more air in depending on what you intend to ride. For example I run a stiffer fork on a flattish run like Sherwood where the bike isn't going to take any big hits, but a stiffer but well damped ride will mean extra speed. At Dalby I'll use a plusher, compliant setting because of the extra drops and steps. 

Trail and error is you friend!


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## smithy92 (16 Jun 2011)

Thanks for that Cubist. 

Absolutely massive help and far more comprehensive than most of the "guides" I've been able to find online!

I guess I'd best get riding!

Thanks again.


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## VamP (17 Jun 2011)

That is an awesome write up and deserves to be a sticky!


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## plainlazy (21 Jun 2011)

Hi smithy92

Try the link below, it has a link to the user manual which i found useful.
There is also some good advice in the Beginners rules and FAQ tread on there too.




http://www.bikeradar.com/forums/vie...sid=91dad986566f414c4cf4de7430005c3b#16889996

Hope this helps


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