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  1. #1
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    Oil, cold and damping performance

    I recently did the fluid and seals in my Fox. The oil this time was 10wt. as opposed to the 7wt, I had been using. No real reason, just a matter of availability.

    I was riding yesterday in the low 30s F. Stopping at a pond to watch the sun and clouds on the water, I absent mindedly squished the fork and noticed the rebound was a good bit slower than normal.

    Obviously cold has an effect on viscosity, but I wouldn't think the low 30s would be cold enough. Am I wrong? How cold does it have to get before damping performance is altered?

    I'm just curious.
    "Bikes aren't fast--people are fast. Bikes are overpriced. It's an important distinction."---BikeSnob NYC

  2. #2
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    Also, depends whether it's synthetic or not.

  3. #3
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    Quote Originally Posted by GrantB
    I recently did the fluid and seals in my Fox. The oil this time was 10wt. as opposed to the 7wt, I had been using. No real reason, just a matter of availability.

    I was riding yesterday in the low 30s F. Stopping at a pond to watch the sun and clouds on the water, I absent mindedly squished the fork and noticed the rebound was a good bit slower than normal.

    Obviously cold has an effect on viscosity, but I wouldn't think the low 30s would be cold enough. Am I wrong? How cold does it have to get before damping performance is altered?

    I'm just curious.

    I doubt the cold is the significant factor. Most if not all shock oils have a very high viscosity index, meaning the viscosity does not change much with temp...(it of course still does)...

    The pour point of most shock oils is around -15F or so so colder...

    My fork starts to set up at about -10 C, the shock at about -15 C.

  4. #4
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    I had the same problem with my dj3 fork. Granted a dj3 is not a high quality fork, and has grease instead of oil, at 30 degrees, the rebound is at least three times slower. Sorry I couldn't be of any assistance.

  5. #5
    www.derbyrims.com
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    I feel the damping firmness change with about 20F degree differences, warmer or colder.

    Like every thing about suspension, some feel differences more than others. I feel the difference in my car's shocks in the morning when the temp drops below 45F or so.

  6. #6
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    Do you know the oil brand?

    Whatever rockshox was using in the late 90's was noticably thicker approaching freezing. Replacing the same oil with the PJ1 and silkolene I was using at the time made a significant improvement in the cold while feeling similar in the warm.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  7. #7
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    I don't know the make of the oil. It is in a Fox branded bottle, marked 10w.
    Last edited by GrantB; 12-14-2010 at 05:05 AM.
    "Bikes aren't fast--people are fast. Bikes are overpriced. It's an important distinction."---BikeSnob NYC

  8. #8
    Waiting for peace
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    In with derby... I notice a change in flow quality at about that change in temperature....

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