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RockShox Revelation fork setup

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RockShox Revelation fork setup

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flag P4w3l
Posted: Mar 20, 2021 at 12:33 Quote
Hi,

Firstly, sorry about the lame questions, I've never played with suspension before and couldn't find an answer online.

I have a 2015 RockShox Revelation RL that originally came on my bike (Giant Anthem Advanced SX 27.5)

I am playing with the fork setup and am a little confused with the sag. The fork travel according to Giant website is 120mm, according to RockShox website is 130mm, and the exposed part of stanchions is about 116mm. Without any load on the bike the sag sits at around 18%. Am I correct to assume that Giant basically shortened the travel of the fork and the sag scale is irrelevant?

I am, together with all the riding gear on me, some 65 kg. I set the air pressure at 80 PSI according to the table on the fork leg. This makes the fork sag some 12mm (~10% of stanchions' length) and on the stanchion scale it shows about 28%. I also tried setting the pressure at 60 PSI, and this gives about 16mm of sag (~14%). Should I lower the pressure even more for the fork to sag some 29mm (25%)? This seems like a big difference, the O-ring already goes all the way up to the crown at 80 PSI after a few runs down a trail. This, however, may be due to too low a rebound, which I'd not adjusted until now, and which was at 3 clicks from fully closed. I now changed it to 8 clicks (out of 20)

The photo below shows the sag with 80 PSI and no load on the bike. Note the sag scale reading ~18% with the fork fully extended (it doesn't extend any more even if I hold the wheel down and try to pull the fork crown up)

photo

photo
flag 8tom8
Posted: Mar 21, 2021 at 9:21 Quote
P4w3l wrote:
Hi,

Firstly, sorry about the lame questions, I've never played with suspension before and couldn't find an answer online.

I have a 2015 RockShox Revelation RL that originally came on my bike (Giant Anthem Advanced SX 27.5)

I am playing with the fork setup and am a little confused with the sag. The fork travel according to Giant website is 120mm, according to RockShox website is 130mm, and the exposed part of stanchions is about 116mm. Without any load on the bike the sag sits at around 18%. Am I correct to assume that Giant basically shortened the travel of the fork and the sag scale is irrelevant?

I am, together with all the riding gear on me, some 65 kg. I set the air pressure at 80 PSI according to the table on the fork leg. This makes the fork sag some 12mm (~10% of stanchions' length) and on the stanchion scale it shows about 28%. I also tried setting the pressure at 60 PSI, and this gives about 16mm of sag (~14%). Should I lower the pressure even more for the fork to sag some 29mm (25%)? This seems like a big difference, the O-ring already goes all the way up to the crown at 80 PSI after a few runs down a trail. This, however, may be due to too low a rebound, which I'd not adjusted until now, and which was at 3 clicks from fully closed. I now changed it to 8 clicks (out of 20)

The photo below shows the sag with 80 PSI and no load on the bike. Note the sag scale reading ~18% with the fork fully extended (it doesn't extend any more even if I hold the wheel down and try to pull the fork crown up)

photo

photo
I once had this with my fork it wasn’t fully extended and what is was for me was there was more air in the negative chamber than the positive chamber which are the two air ‘systems’ (I don’t know what to say). The positive is what suspends your weight and the negative is the one that pulls the fork back down. What I did was take all the air out the fork (make sure you know what pressure you had in before hand) pull it down and then get all 130mm of the stanction showing and then pump it up.
flag johnovey
O+
Posted: Mar 21, 2021 at 10:20 Quote
That is a Solo air, so no negative air chamber on it.
I would suggest than there is pressure built up in the lowers. Do a lower leg service, or for a quick fix, remove the wheel, loosen the bottom leg bolts & give them a tap to loosen them. That should let out the built up air. Pull up on the legs to see if full travel is back. Then tighten the bolts.
I see this is a 2015 model. If you have never done a fork service, you absolutely should!
flag 8tom8
Posted: Mar 21, 2021 at 11:31 Quote
johnovey wrote:
That is a Solo air, so no negative air chamber on it.
I would suggest than there is pressure built up in the lowers. Do a lower leg service, or for a quick fix, remove the wheel, loosen the bottom leg bolts & give them a tap to loosen them. That should let out the built up air. Pull up on the legs to see if full travel is back. Then tighten the bolts.
I see this is a 2015 model. If you have never done a fork service, you absolutely should!
can you not realease pressure by purging the seals with a zip tie?
flag johnovey
O+
Posted: Mar 21, 2021 at 15:25 Quote
Yes, maybe. I've had better luck the other way.
Really though, if the fork has not been serviced in 5 yrs........Do it!
flag TibZ
Posted: Mar 21, 2021 at 15:33 Quote
johnovey wrote:
That is a Solo air, so no negative air chamber on it.

There is a negative chamber on the solo air. The debonair version just increased the size of it (relative to the positive chamber).
It is supposed to passively equalize with the positive chamber (the one you pump up). The port between the 2 might be blocked by grease. The best option would probably be to do an air spring (and lower legs, obviously, as it will be necessary to remove them anyway) service.
flag johnovey
O+
Posted: Mar 21, 2021 at 15:47 Quote
I guess I should have said that there is not an adjustable negative chamber on the Solo Air.
flag 8tom8
Posted: Mar 23, 2021 at 13:12 Quote
TibZ wrote:
johnovey wrote:
That is a Solo air, so no negative air chamber on it.

There is a negative chamber on the solo air. The debonair version just increased the size of it (relative to the positive chamber).
It is supposed to passively equalize with the positive chamber (the one you pump up). The port between the 2 might be blocked by grease. The best option would probably be to do an air spring (and lower legs, obviously, as it will be necessary to remove them anyway) service.
yeah if they arnt equal the fork gets like yours it happens to me kinda often when you go into a really deep compression probably because o don’t have enough air in and many volume spacers
flag P4w3l
Posted: Mar 24, 2021 at 8:06 Quote
Thank you for all the answers, the fork indeed has not been serviced since I got the bike 5 years ago. I’m a roadie and the MTB is being used very occasionally (one trip to the Alps, several to Lake District, probably no more than 500 miles in total). I will get it serviced nonetheless, hopefully it’ll solve the problem.
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