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x-post.....

Googled and searched mtbr and read til I was confused. Trying to set up my Reba 29 Brain fork on the Evo R Stumpjumper Expert and need help.

Released air from both neg and pos chambers. Filled pos chamber to 60% of body weight (I'm about 170 geared up) which is about 105 psi and put 90 psi in the neg chamber.

The o-ring does not move when I sit on to check sag.

I'm a Brain newbie and know what it does while riding, but presumed sag would still be measured. I have the Brain anywhere from full slow to full fast and it does not effect sag. Same with rebound.

My other bikes have Fox front & rear, and sag settings are a no-brainer (pun intended) to achieve 20% or 25% sag.

Is it not supposed to show measurable sag (and therefore the o-ring is to check full travel?).

Mods please move to the appropriate forum if more applicable than the Speci.
 

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You should have zero pressure in the negative chamber when setting the sag
No, you should never have greater than about 15psi difference between the +ve & -ve chambers.

The procedure for sag is as above: brain fully off, and +ve/-ve pressures the same. If you are just starting out, the pressure should be the nominal value marked out of the fork for your weight.
 

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I have just started attempting to get this dialed in with my bike shop. We are recording every change and it seems to be coming around, keep working on it.
 

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Yea, this fork really confuses me. I tried the no air in negative chamber sag.... way no good. I tried the info on the fork leg, settings on the doc that is posted and just could not get good sag numbers but didn't open the brain all the way up. will try that next.

My issue is lack of plushness, just way too harsh. Then when in corners and hitting roots or changes in the trail the fork is just not compliant enough to give me confidence so I am running the brain wide open and still not really happy.

Also not sure a inerta/platform fork is a good choice for a SS, that is what I am running... should be a true compression circuit and or lock out.

I did notice that the pressures on the specialized tuning doc are a lower range then the numbers on the fork leg...

So my question is: Is the brain a stable platform blow off like the old Teralogic forks or a tuneable compression system?

Just my experiences and questions.....
 

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old fart
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Yea, this fork really confuses me. I tried the no air in negative chamber sag.... way no good. I tried the info on the fork leg, settings on the doc that is posted and just could not get good sag numbers but didn't open the brain all the way up. will try that next.

My issue is lack of plushness, just way too harsh. Then when in corners and hitting roots or changes in the trail the fork is just not compliant enough to give me confidence so I am running the brain wide open and still not really happy.

Also not sure a inerta/platform fork is a good choice for a SS, that is what I am running... should be a true compression circuit and or lock out.

I did notice that the pressures on the specialized tuning doc are a lower range then the numbers on the fork leg...

So my question is: Is the brain a stable platform blow off like the old Teralogic forks or a tuneable compression system?

Just my experiences and questions.....
Start with the correct sag first. Then tune from there. Otherwise you end up chasing your tail. Just remember to have the brain fully off when you set sag. The psi numbers on the fork are just a starting guide. Sag will be right when your psi is correct.
 

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No clue about specialeds and the brain (personally hate the idea and think it's for racer boys) but I know I have never had the perfect sag on any of my Rebas, ever. I generally set it up to about the 60% of body weight and then set neg pressure about 70-80% of that and give it a go and check how it feels and uses travel. If it feels fine and uses up the travel nicely, say 90% on most rides and on the occasional big stuff all, then I'm happy.
 

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x-post.....

Googled and searched mtbr and read til I was confused. Trying to set up my Reba 29 Brain fork on the Evo R Stumpjumper Expert and need help.

Released air from both neg and pos chambers. Filled pos chamber to 60% of body weight (I'm about 170 geared up) which is about 105 psi and put 90 psi in the neg chamber.

The o-ring does not move when I sit on to check sag.

I'm a Brain newbie and know what it does while riding, but presumed sag would still be measured. I have the Brain anywhere from full slow to full fast and it does not effect sag. Same with rebound.

My other bikes have Fox front & rear, and sag settings are a no-brainer (pun intended) to achieve 20% or 25% sag.

Is it not supposed to show measurable sag (and therefore the o-ring is to check full travel?).

Mods please move to the appropriate forum if more applicable than the Speci.
Here is the manual for that fork:

http://service.specialized.com/coll...df/Fork---RockShox-Reba-29-SID-Brain-Fork.pdf
 

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