FAQs - Suspension
Rockshox SID problem diagnosis
Note: these diagnostic procedures will apply to pretty much any Rockshox dual air fork including Reba, Reba 29er and Revelation forks.
Issue: fork stuck down or not returning to full travel
There are two potential causes:
- damper fluid leaking past rebound rod seal into fork lowers;
- leaking air piston seal allowing positive air pressure into the negative air chamber;
- leaking positive air spring schrader valve or top cap.
Diagnostic procedure:
- let all air pressure out of neg side - does the fork return to having full travel?
- increase air pressure in pos side (say 100psi) with no pressure in neg side - does the fork length increase?
- cycle fork with 100 psi pos and no neg pressure - is there now any pressure in neg side?
If the answer to any of these questions is "yes" then the o-ring on the air piston is leaking. If the answer to all three questions is "no" then damping fluid in the damping leg has leaked into the fork lowers and the rebound rod seal (possibly just an o-ring) needs replacing.
If you suspect a leaking positive air spring schrader valve or top cap then paint a water and detergent mix around the top cap and schrader valve and see if there are any air bubbles. To fix see if the top cap is tight, replace the valve or the top cap o-ring.
Issue: fork not achieving full travel
There are three potential causes:
- too much pressure in the positive chamber;
- too much pressure in the positive and negative chamber;
- damper fluid leaking past rebound rod seal into fork lowers.
Diagnostic procedure:
- let all air pressure out of the positive and negative air chambers - can you compress the fork all the way down?
If the answer is YES, then you're running too much pressure in the positive chamber. Set your positive pressure to achieve the desired amount of sag .
If the answer is NO, then damping fluid has leaked into the lowers past the rebound rod seal. You can't compress damping fluid so this is stopping the forks achieving full travel.
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