Travel on Rockshox Revelation Race Dual Air

myopic

Just about to fit these new forks. They are supposed to be 140mm, and if I let out all of the air, then there is 140 mm of stantion between the seals and the crown. However, if I compress the forks, there is only 120 mm travel before they bottom out.

Does this mean that the
(i) internal spacers have been set-up for 120mm travel, or
(ii) 120mm is as much as I would expect to get, or
(iii) does this suggest there is another problem?

nicklouse

sounds like there is still air in there

but what year are they?

myopic

They were sold as 2010 (they have the powerbulges on the legs if that's any help), so I would have exxpected max of 150 mm was possible in theory, though I don't want that much, so if they are 2009 with max of 140mm that's not a problem. No box or manual with them....

Pretty sure I have let all the air out, I compressed them before trying again and only a little air came out with no more compression. Also it feels like they are up against someithgn solid at the end of the travel

nicklouse

TBH i would be talking to Merlin and find out what you have bought.

as it sounds like it is an OE fork so could be anything.

myopic

Thanks, Nick. I'm going to talk to them, but before I do, I just want to establish if there is a problem or not. the fork hadn't been fitted to anything - no cut steerer tube or any fittings to it. The likely answer will be send it back if I'm not happy, which I don't want to do if all I need to do is open it up and move some spacers - but I don't want to do that if I then find a problem and need to send them back anyway!

nicklouse

well the spacers change the total length of the fork and it could be 150/140/130 but is it is OE it could be anything and may not be changeable.

so find out what you have been sent.

myopic

Thanks, Nick. I gave them a call and it sounds like these were a batch shipped with spacers set to 120mm travel. So I should be able to move these around to get the travel I want.

On my other forks travel spec = stantion length. In other words, will these always be 2 cm longer than the travel, and is that normal?

nicklouse

should not be a 120 option if 2010.

nope travel change on RS forks equals longer/shorter forks

travel and AC measurement for 2010 Revs
150 529
140 519
130 509

download-able

http://www.sram.com/_media/techdocs/MY2 ... 20Axle.pdf

The Northern Monkey

I think you only get the powerbulges on the 2010 revs.... 09 didn't have them IIRC.

2010 all travel race revs can be adjusted using spacers. Travel available is 150mm, 140mm and 130mm.


The only rev race to go down to 120mm is the air U-turn.

myopic

Is the AC distance from the centre of the axle to where the crown race would sit? If so, I've got 520mm, which would suggest that it is correct for a 140 mm fork, but only with 120 mm travel. Which would suggest that either there is something strange inside the fork or it has been made with extra long stantions

If it is to the base of the crown (ie bottom of steerer tube), then it is 499mm, which would fit with what might be expected of a 120mm travel from the table.

nicklouse

center of axle to the top of the crown where the race sits.

drawing for the Pike (no rev available!)

http://www.sram.com/_media/techdocs/Pike%20(MY2009)%20-%20User%20Specs%20and%20Standards.pdf

myopic

Thanks, Nick!

So, if I do move the spacers to get 140mm travel(assuming this is possible), I'll increase the AC by 2 cm which would be 540mm, which would be too long and would screw up the geometry?

The only way I can see this happening is if the fork has been specc'd with shorter inners, or longer stantions, which seems improbable! Unless there is something put together wrongly inside it - is there anything that could cause this?

The Northern Monkey

Like nick said... if its an OE fork, it could be any combination.

If merlin say its 120mm and you were expecting a 150mm (with 140mm/130mm spacers) i'd phone them and get them to confirm what they actually have sent!

Then send it back if they've sent you a random OEM fork!

myopic

I just don't get it Ben - you wouldn't spec different lengths of stantions or inners if you wanted to change the travel - you would just use the spacers surely - even if it was an OEM order?

There must be abother explanation. Talking to supplier about it, in the meantime if anyone has ideas I would be grateful!!

nicklouse

personally i would be sending it back.

as the travel should be about the visible leg length.

myopic

Cheers, Nick. I'll update once outcome established.

Peterpoddy

Righto.....

If there's 140mm of stanchion showing when the forks are pumped up, then you have 140mm of travel. That's a fact. No need to faff with spacers.
If the travel has been reduced, then you'll have less stanchion showing, as the spacers drag the fork down to reduce it. That's the whole point of a shorter trvel fork - It's shorter overall to fit different frames

When you let the air out and try to compress, there's still air in the chamber which compresses as you push down on the fork, limiting the travel, in a way.

There's also a rubber bump stop inside the fork. In use, you'll probably find the fork stops 10mm-ish before full travel is given up. BUT if you hit the fork hard enough, and I mean REALLY hard, the bump stop WILL compress and you WILL get full travel.... Believe me, you will....

It's the way lots of forks are made "140mm" is almost a nominal figure in daily use to be honest.

myopic

Don't think it's a rubber bump stop Peter, but thanks anyway. Its a metal on metal "clunk" 20mm before end of expected travel.

Regarind some residual air, I tried releasing extra air with fork compressed and its definitely not that.

nicklouse

when fully compressed there should be about 5 mm of "leg" visible.

myopic

That's what I thought - there's actually about 24mm left showing when it bottoms out with a metallic sounding "clunk". (ie actual travkle is less than 120 mm) Speaking to supplier about getting it all resolved, but good to have the reassurance that its not right!

myopic

Problem was a faulty cartridge - Merlin took the forks back, replaced it and now working as they should.

The Northern Monkey

Yay

Glad you got them sorted!

myopic

Me too