Suspension - Am I getting enough Travel?

Jenny Taylia

Hi.

I've got a set of RS Revelation U-turn Dual air's, which go up to 140mm travel. Just went out for a ride, after fitting a zip-tie to the fork leg and found that I'm only getting 95mm travel. I've previously set the pressures to the RS recommended for my weight but does this mean that I need to reduce the pressures yet further, until I get max travel?

I also have a Fox Float RP2 rear shock and I set up the sag with the Fox Sag-Meter and again, it has recommended pressure, however, I am only getting 25mm of travel on the shock (O-ring on the shaft measured)

How much travel should I be getting from the rear shock? Can't find anything on the Fox site.

Any suggestions for the above please?

Thanks

supersonic

Run more sag, ride, see how it goes. Sounds like they are too firm. Recommended pressures are usually too firm.

nicklouse

Jenny Taylia wrote:

Hi.

I've got a set of RS Revelation U-turn Dual air's, which go up to 140mm travel. Just went out for a ride, after fitting a zip-tie to the fork leg and found that I'm only getting 95mm travel. I've previously set the pressures to the RS recommended for my weight but does this mean that I need to reduce the pressures yet further, until I get max travel?

I also have a Fox Float RP2 rear shock and I set up the sag with the Fox Sag-Meter and again, it has recommended pressure, however, I am only getting 25mm of travel on the shock (O-ring on the shaft measured)

How much travel should I be getting from the rear shock? Can't find anything on the Fox site.

Any suggestions for the above please?

Thanks

read the setting up dual air forks in the FAQs. forget what any fork shock maker suggests as that is only a guess. set your sag go ride and tweek as needed.

Jenny Taylia

[/quote]
read the setting up dual air forks in the FAQs. forget what any fork shock maker suggests as that is only a guess. set your sag go ride and tweek as needed.[/quote]

Can't find the MTB FAQ's, only road bike, can you provide a link please?

thanks

nicklouse

at the top of the tech forum

viewforum.php?f=10004

Jenny Taylia

Well, just read Supersonic's very informative FAQ on setting up the forks. Mine are 2009 so I don't know if they count as "Old" or "New" regarding the setting up (but I've tried both methods) but after an hour of fiddling :roll:
I find that the only way to maintain 140mm of travel and to have 35mm of sag (25%) is to have 40psi in the Neg and 70psi in the Pos chambers (Set with the rebound damping totally off)

If I match the + & - chamber's psi's, I get only about 120mm or less of travel. Ideally, I'd like 140mm of travel, a slightly softer "Start" to the travel (By having 10% more in the -ve chamber, as per the FAQ)

If I boost the +ve to 130psi and the -ve to 130psi, I don't get enough sag and it all seems way too firm. Tried many combinations inbetween too.

I must be doing something wrong but can't figure out what. I'm 100kg and the RS sticker says 170psi upwards for my weight. Where are RS getting their 170psi figures from? it would be like a fixed fork at that!

HELP please

bails87

What are you doing to check the travel? Just bouncing on the forks?

Just set the sag while in the attack position (standing on pedals, weight forwards) and tweak from there.

Jenny Taylia

bails87 wrote:

What are you doing to check the travel? Just bouncing on the forks?

Just set the sag while in the attack position (standing on pedals, weight forwards) and tweak from there.

No, not "Just bouncing on the forks" :roll: doing as RS suggest and sitting on the bike in normal riding position, with all my gear on, climbing off and measuring the distance from the zip-tie to the seal

The position you suggest would give a "False" reading as downhills, where the forks work most, you're leaning back, weight over the back wheel, surely? but what do I know? (Hence the questions )

bails87

That's measuring sag, not travel.


Edit: I clicked edit instead of quote, so rewrote this post....kind of.

The Rookie

+1 that's setting sag not measuring travel!

Jenny Taylia

I've been measuring the Sag, as stated above, on the bike with my riding gear on. measuring from the displaced zip-tie to the seal, once dismounted.

As for the travel, the forks are U-Turn's, as in the 1st post and have travel amounts stamped on the stansions, which is where I've been quoting the "Travel" amount from. When I've said I can't get 140mm travel, I mean that the seals are settled at the 120mm or less marker, even on full wind-up. I have to have the very low pressures quoted above, to achieve the correct sag and the 140mm travel.

Hope this clarifies and enables a forthcoming solution

bails87

Jenny Taylia wrote:

I've been measuring the Sag, as stated above.:

Like this:

Jenny Taylia wrote:

doing as RS suggest and sitting on the bike in normal riding position, with all my gear on, climbing off and measuring the distance from the zip-tie to the seal

?
Right, that's almost right. But as already said you should be in the 'attack position'.

Jenny Taylia wrote:

As for the travel, the forks are U-Turn's, as in the 1st post and have travel amounts stamped on the stansions, which is where I've been quoting the "Travel" amount from. When I've said I can't get 140mm travel, I mean that the seals are settled at the 120mm or less marker, even on full wind-up. I have to have very low pressures to achieve the correct sag and the 140mm travel.

Hope this clarifies and enables a forthcoming solution

Again, are you measuring it while you're off the bike?

EDIT: How can you have 140mm travel on a 140mm stanchion AND 25% sag at the same time?!

But tbh, ignore the travel. The forks shouldn't be fully extended when you're sitting on the bike btw. If you're riding thorugh a corner and there's a little dip in the ground, the forks extend to keep the wheel on the ground. That's why you have sag, forks don't just compress the absorb impacts, they extend to maintain traction.

The main point is: Set the sag while in the attack position. Then come back and hopefully tell us it's working.

Btw, my point about measuring travel by bouncing the forks wasn't sarcastic. That's how you would measure travel, assuming you could put enough force through the forks to push them down. Otherwise you'd take all the air out and compress them.

The Rookie

Clearly the forsk are capable of the 140mm idel, so just set the +ve and -ve pressure to get the ride quality you like, numbers are irrelevant as long as you're not bottoming out to often of topping out to often.....

Jenny Taylia

Sag is measured as I've stated and the travel is done by reading the stansion marker whilst OFF the bike.

Surely the marker should show 140mm travel, if the u-turn is wound out fully? Then, when I sit on the bike, that gives the sag (Which should be 25% - 30% of the 140mm travel) for those "Dips round corners" etc to prevent the topping-out.

This is where I'm missing something. OFF the bike, with higher pressures - the correct sag gives me only 120mm or less of travel (On the markers).

I get the bit about ignoring the figures and getting the "Ride" I like but my pressures are way less than RS suggest for the optimum travel / ride

bails87

Stand on the bike, in the attack position. Set the pressure to give you 25-30% sag in that position.

If you're setting the sag with hardly any weight on the forks then you're going to be running low pressures, which might make the forks sit into their travel a bit when they've only got the weight of the bike on them.

Set the sag in the attack position. Because that's the position you'll be in when you're actually riding the bike and you want the fork to be tracking the ground.

Jenny Taylia

bails87 wrote:

Stand on the bike, in the attack position. Set the pressure to give you 25-30% sag in that position.

If you're setting the sag with hardly any weight on the forks then you're going to be running low pressures, which might make the forks sit into their travel a bit when they've only got the weight of the bike on them.

Set the sag in the attack position. Because that's the position you'll be in when you're actually riding the bike and you want the fork to be tracking the ground.

Well, we're gonna have to agree to differ on this.

the only time I ever stand up, leaning forwards, is when the forks are locked out and I'm climbing a hill. The most part of my riding is seated (How I've been setting my sag and how SRAM say to do it) and the forks work hardest when I'm standing and leaning back as far as I can, on descents.

Sitting to set the sag is the mid / average position of bike use.

Here's what SRAM say (How I've been doing it) - click the top choice, Dual Air Tuning Guide 2001-2011
http://www.sram.com/service/rockshox/7,107

The Northern Monkey

Maybe you aren't riding the bike in a way that needs 140mm travel.. regardless of how you set the fork up. The terrain determins how much travel is required, the fork should be set up as Bails explains above.

If you're sat down all the time, then the likliehood is that you aren't riding anything that warrants 140mm in the 1st place.

bails87

search.php?keywords=sag+attack&fid%5B0%5D=10004

Plyphon

Do you not stand up to sprint?

What about standing up for rock gardens, roots, or faster descents that don't require you to shift your weight back but require you to "attack" the trail?

Even if you ride pure XC you're going to have to stand up at some point.

The Rookie

Hmm never stand up.....never manual? Rock gardens? Corners? Berms? I'm lost on this......

Regardless, standing up puts more weight on the front, so will inevitably use more travel, as you don't 'Attack' anything then you're not putting enough energy into the fork for it to use it's 140mm.

cooldad

I only really ride XC (gnarrly rad XC obviously) and the only time I'm seated is on fairly smooth straight bits. As soon as it's up, down, twisty or bumpy I stand, and that's on a full sus. All the fun bits really.

felix.london

The Northern Monkey wrote:

Maybe you aren't riding the bike in a way that needs 140mm travel.. regardless of how you set the fork up

This ^^

If I pop to the shops I'm not gonna be surprised if I don't use my 120mm of fork travel from maybe hopping off a couple of kerbs. Ride harder.

And re. setting sag - if you're sitting down more than your standing up your on the wrong bike for sure. To use 140mm of travel you need to be standing up or else you'll injure yourself and damage the bike. That's some seriously big hits needed to soak up that lot. I use my 120mm a few times on each ride but I'm clattering down rock gardens and going (little) jumps and drops and sh1t

leaflite

If the forks are getting "sucked down"-less than 140mm stanchion visible when not on the bike-try putting slightly more psi in the positive chamber than the negative.