Fork Spring Rate Verification

From Unofficial Zero Manual
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Reference
How to Verify Fork Spring Rate
Tools
  • A tip-tie long enough to wrap around the fork tube.
Steps
  1. Add a zip-tie to the the fork tube.
    • Make sure it is snug so it stays in the place it was last pushed too.
    • Once the zip-tie is on the fork tube, you push it up to rest it against the upper fork.
  2. Measure bike sag (unloaded)
    Lift the front fork off the ground and measure the gap (zip-tie to fork gap) created by the front weight of the bike.
  3. Measure rider sag (loaded)
    1. Now push zip-tie back up the fork, then sit on the bike and raise your feet so all of your weight is carried through the suspension.
    2. Then carefully dismount and put kickstand down.
    3. Measure the gap (zip-tie to fork) created by your weight.
    4. Add this gap measurement to the bike sag measurement, this is the total sag.
    This measurement should be around 25% of the working range of the front suspension.
    Now that is a guideline; it can be higher or lower than 25%.
    It depends on what is happening when you are loading up the suspension (upper end).
  4. Checking the upper end by using the zip-tie.
    After riding, check the location of the zip-tie: the gap from the fork to the zip-tie.
    Lets say the measurement is 5". Then you would know the total max travel used was 5" + bike sag measurement.
That total measurement should never equal the total suspension travel amount (6", I think based on your posting).
  • If it equal, then you are bottoming out. Increase the preload and see if this keeps you from bottoming out.
  • If you use max preload and are still bottoming out, you will need stronger springs.
  • If you find you are only using 75% to 80% of the max suspension travel, you can reduce the preload spacer length some or you can live with this.
  • If you are only using ~50% or less of the suspension travel, your springs are probably too stiff. You should swap springs to a lower rate spring.