Originally Posted by grnmasi

My partner had been using a Bolt on her Trek along with the Duotrap S speed/cadence sensor while I use the Edge 830 with Garmin Speed 2 and Cadence Sensors on my bike. We noticed that for every single ride that we do together, and I am counting dozens, the Bolt always registers 0.2 to 0.4 miles (most often 0.2 miles) less total distance on ~ 25 mile ride. We have both computers set to autocalibrate wheel sizes. We have seen that difference on both longer and shorter rides. Although the consistent difference (rather than a random difference due to precision) bothered me a bit, I just attributed it to differences in the pairing of the computers with the different sensors on the two bikes.

But recently I was able to compare both computers paired with the exact same sensors (Garmin Speed/Cadence 2) on my bike for close to a dozen rides. The difference of 0.2 to 0.4 miles (Bolt always lower) on a 25 mile remain still remains even using the same bike and paired sensors. I really don't have a possible explanation except that it is something regarding the difference in the autocalibrate functions on the two computers. I guess the next thing to try when I get a chance to ride is to enter a fixed and same value for the wheel calibration for both computers and see what happens.

In the meantime, any ideas on what is causing the difference? In reality, I don't know which is "correct".

Thanks.