View Single Post
Old 12-30-18 | 11:12 AM
  #13  
Robert A
Senior Member
10 Anniversary
 
Joined: Sep 2012
Posts: 758
Likes: 64
From: Los Angeles

Bikes: 2019 CAAD12, 2015 Specialized Sirrus Comp

Yes, that's how I measured the circumference of exactly 84" or 2133.6mm. The Bolt is calibrated to 2136mm, so that explains 0.2% of the 5% difference. The overread on the Bolt is rather consistent compared to GPS and by a fairly wide margin -- about 1 mph. Makes me question if the speed sensor is correctly calibrated.

Originally Posted by woodcraft
Did you do a roll-out to measure the wheel circumference?

Just for kicks I tried wrapping a (fabric) tape around the tire, vs rolling out & it came out at least 1cm different.

I would get that dialed in, & then not worry about it. GPS does stuff like measure to the riverbed when you go over a bridge,

& Strava on a phone can include your trip into the bathroom- it's all an approximation.
Robert A is offline  
Reply