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Old 12-30-18 | 02:14 PM
  #18  
Robert A
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Joined: Sep 2012
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From: Los Angeles

Bikes: 2019 CAAD12, 2015 Specialized Sirrus Comp

I did measure rollout unloaded. Is measuring the wheel loaded likely to make anything close to a 5% difference in circumference?

Originally Posted by njkayaker
You have to measure roll-out with the rider on the bike since the tires deform.

You want the circumference of the circle with the vertical radius from the hub to the road with the bike loaded. This radius is shorter than with the tire without any load.

GPS distance will tend to be lower than the distance measured by a correctly-calibrated wheel sensor. The measurement "error" (variability) is larger for GPS.

Last edited by Robert A; 12-30-18 at 02:22 PM.
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