Bought some Rockshox Revs

heavy_rat

Steerer cut and forks fitted. Now what?

The manual is crap. I set the psi to about the right setting for my weight. Is there anything else to do?

Would anyone be kind enough to explain how the positive negative chambers work?

Anonymous

Basically, positive pressure is your spring. Negative pressure is an opposing spring which is meant to alleviate stiction, making the fork more supple.

Have a look at the tech links sticky,and there's a link to some useful Fox videos on suspension tuning. The same principles apply to any manufacturer though.

nicklouse

read the dual air setting info in the FAQs?

which basically just repeats what is said in the manual.

The Northern Monkey

from what I remember... the dual air guid in the FAQ doesn't work for the 2010 revs... you cant set your sag without having put air in both chambers... the fork effectivly locks out (assuming becasue of a vacuum?).

No matter what I did I jsut got no sag by just putting air in whichever chamber it says in the guide!

Oh and the manual (the on online and the one in the box) doesn't mention how to set up the forks!

I guessed my PSI using the guage on the forks and put that in both +ve and -ve chambers.
Then added more/less as needed for correct sag.
Then tuned the -ve chamber.

supersonic

So with no air in the fork, it did not compress at all? Or at which point did it not compress?

The Northern Monkey

with no air it would compress...

but as soon as you add air to the +ve chamber with nothing in the -ve (and i'm talking as little as 50psi here) the fork would just lock out solid!

Don't think I was doing anything wrong but I just couldn't get the method in the FAQ's to work... tried a fair few times too!

Infact... i'll even have another go tonight for you

Anonymous

50PSI is a lot. IIRC my 66s only needed something silly like 20 PSI.
They didn't work though mind... (which reminds me I need to get in touch with windwave, still haven't got a reply)

The Northern Monkey

yeehaamcgee wrote:

50PSI is a lot. IIRC my 66s only needed something silly like 20 PSI.
They didn't work though mind... (which reminds me I need to get in touch with windwave, still haven't got a reply)

140 - 150psi in the revs for me... so its not much...

RS recommend 130psi+ for someone a bit lighter than me...

Anonymous

hmm. and you're certain that it was locking out with air only in the +ve side?

jairaj

I found exactly the same problem as Ben, took me ages to finally work out what was going on, thought I was being stupid or something.

You defiantly need the same amount of air in +ve and -ve chambers first to set the sag, then tune the -ve.

bails87

The Northern Monkey wrote:

yeehaamcgee wrote:

50PSI is a lot. IIRC my 66s only needed something silly like 20 PSI.
They didn't work though mind... (which reminds me I need to get in touch with windwave, still haven't got a reply)

140 - 150psi in the revs for me... so its not much...

RS recommend 130psi+ for someone a bit lighter than me...

Yeah, I'm oly 10 stone and I need around 100psi in my Rebas.

Aren't the Marzocchis different? So they use the air to tune, rather than as the only spring?

My 08 Rebas don't lock out, but they are very firm with the -ve empty.

The Northern Monkey

yeehaamcgee wrote:

hmm. and you're certain that it was locking out with air only in the +ve side?

1000000% sure...

jairaj
Glad that someone else agrees with me too!

Anonymous

No, the Marzocchis I had were air spring only, but the -ve air spring was meant to set itself up automagically due to some clever valving that never worked.

Seems like a faff to me if you have to have both set the same, just to set sag.

ian_worby

I'm not sure what manual people have been reading but mine clearly states what to do on pages 5 and 6 and gives rough guides on pressures to use

http://www.sram.com/_media/techdocs/95- ... 0print.pdf

The Northern Monkey

ian_worby wrote:

I'm not sure what manual people have been reading but mine clearly states what to do on pages 5 and 6 and gives rough guides on pressures to use

http://www.sram.com/_media/techdocs/95- ... 0print.pdf

think you'll find that is the 2008 manual.

supersonic

The guide I wrote pretty much reflects the older manual and was actually adapted from MTBR.

I know however that RS do tweak things, so if this method is not working for newer forks than I will indeed change it.

Have RS got newer manuals up?

The Northern Monkey

http://www.sram.com/en/service/rockshox ... ubcatID=12

2nd one down is the one in the 2010 box... there's nout to do with setting up the fork in it though


Literally just set your pressure in both +ve and -ve to check the sag... add more/less as needed.
Then tune the -ve as per your instructions.


thats what I did anyways

alexj2233

I think that the reason that why it would not move with nothing in the -ve chamber is because as yeehaa said earlier, the negative opposes the positive to reduce stiction. Therefore, with nothing in the negative there is nothing acting against the positive which i presume is how RS have set it to work therefore it wont move.

Although, i may be completely wrong

Anonymous

there will always be atmospheric pressure in the -ve chamber even if you let all the pressure out though. That shouldn't be enough to totally counter the +ve side.

Quirrel

yeehaamcgee wrote:

there will always be atmospheric pressure in the -ve chamber even if you let all the pressure out though. That shouldn't be enough to totally counter the +ve side.

It's a sealed system isn't it?

Therefore if you have no or little air pressure in the system fighting against 100PSI of air from the opposite direction, there will be no way it can 'push' back and therefore locks out.

Dick Scruttock

I round that the advised RS settings on the fork leg were very high.

Anonymous

but the -ve acts to pull the forks down. Atmospheric air pressure alone shouldn't be able to do that. It also shouldn't be enough to stop the +ve from working at all.

MarkLG

[quote="heavy_rat" I set the psi to about the right setting for my weight. Is there anything else to do?

Would anyone be kind enough to explain how the positive negative chambers work? [/quote]

That really is about it for setup. You'll probably find the recommended pressures on the fork leg are a bit on the high side to get proper sag and make full use of the available travel.
Basically +ve pressure determines spring rate and -ve tunes the feel.
Start with equal pressure in both until you get the sag set.
Once you're happy with the sag you can add a bit of air to the -ve air to give a softer, more supple feel. Or take a bit out if you prefer a firmer feel.

I set the robound at about 4 clicks from fastest on the red adjuster at the bottom of the leg.
If there's a small adjuster above the lockout dial then this will adjust the force needed to overcome the manual lockout.