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Fork oil - why give heights not millilitres?

Discussion in 'Technical and Troubleshooting Torque' started by Loz, Sep 5, 2009.

  1. Just wondering if anyone might know - why do so many manufactureres specify fork oil in mm from the top of the tube as opposed to straight millilitres? Firstly, it's harder to measure. Secondly, if you don't pump the damping rod around a bunch it's easy to get it wrong.

    Seems to me that giving the exact amount of oil to put in each fork is a much more consistent instruction...

  2. probably to make it difficult for people to service them at home.
  3. Good question actually!
  4. Because there's empty as in had everything apart, and then all different sorts of "drained" but not disassembled.

    The critical thing is the air gap above the oil level because the air volume determines part of the overall spring rate.
  5. +1 to that. The only relevant measurement is the air gap.
  6. Besides Loz, I thought you were all about the rod pumping.
  7. And with oil too. Pumping rods with lots of oil....
  8. +1, if you just unscrew the drain bolt, you'll need to put less oil in then if you split and cleaned everything. And it's more critical that the air/oil ratio is equal. Same as increasing the oil height to harden the ride.
  9. Just to be contrary (me, contrary? :wink: ), I'd vote for distance from fork top being easier to measure with more widely available tools.

    Maybe it's just me though. I don't own any accurate volume measuring devices (none that I'd trust for the relatively small volume of fork oil required anyway), but an accurate depth measurement can be made with a suitable dipstick and a steel rule, which I do have.
  10. Ooo errr.