Help with Sid shock on older NRS XC bike, please- Mtbr.com
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  1. #1
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    Help with Sid shock on older NRS XC bike, please

    Hi,
    I have a 1999-2000 NRS that I have been using as a xc bike. It has a Rock Shox SID rear shock with positive and negative air chambers and no external rebound. I have been running it with my body weight in both chambers and it works okay, but I was told different things about correct setup, or how it was supposed to be setup for the NRS linkage:

    put my body weight or similar in positive air chamber and to only run about 50 psi in negative air chamber. Result: zero sag and has very locked out feel to it but takes small bumps; rear end skips around and does not take bumps or hits well at all on any real downhill, but does pedal much more firmly. but pogos worse probably due to no rebound.

    Please advise on setup-if the bike was designed to have just 50pse in the negative, and/or to have zero sag, I'll run it like that and will just have to figure it's almost a hardtail on any real downhills, and will be prepared for the rear end skipping around, brake jacking and throwing bike onto its nose.
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  2. #2
    Former Bike Wrench
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    1999-2000 the NRS was called XTC DS2 with the non-adjustable SID shock.

    The NRS suspension was designed for efficiency over performance. The system is designed around running the shock with zero sag...running more pressure in the negative air might help a little but the real issue (besides the fact this suspension design was never a good plush design in the first place) is that the rebound setting is simply too light for your weight. You might look for a SID XC or SL shock on e-bay (6.5" x 1.5") which would help as they have adjustable rebound.

  3. #3
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    Yes, NRS was designed to use no sag, it should stay topped-out while pedaliing but move over bumps.

    But, having no rebound adjust on your shock does make setup more difficult.
    Why not try the negative chamber at 50psi as recommended, then lower the positive pressure until it gets smoother over bumps and general riding (while staying topped out while pedaling on a smooth trail).

    if you don't like that setup, increase the negative pressure a bit more.

    Like was said, you might find a used SID with rebound adjust at a decent price, but it may need new seals if it's used.

  4. #4
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    Slightly of topic but seeing how the NRS has a horste link, does this mean that bikes with this type of link should run little to no sag?

    I have a KHS xc004 with a SID XC (with external rebound adj) and I'm running 110lbs in the + and 50lbs in the -. This gives me about 25-30% sag.

  5. #5
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    Quote Originally Posted by the-one1
    Slightly of topic but seeing how the NRS has a horste link, does this mean that bikes with this type of link should run little to no sag?

    I have a KHS xc004 with a SID XC (with external rebound adj) and I'm running 110lbs in the + and 50lbs in the -. This gives me about 25-30% sag.
    The horst link on the NRS is in a different position as other horst link designs and was designed to run with very little to no sag.... This was due to the fact that the rear would extend strongly under chain tension due to the position of the horst link..... If there was 30% sag the bike would bob a lot under hard pedalling due to the shock extending, den settling into it's sag on every pedal stroke....

    Other models of Horst links need sag, so u don't have to do anything to the KHS....

    Cheers!
    Mas

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