Originally Posted by JLauren

I just put a Cateye Astrale on my road bike, mainly because my olde Sigma 500 was showing some anomalies, and partly because it was time to spend some money on cycling . The Astrale has the wheel pickup on the rear, the SIgma on the front.

Today I rode with both computers. For the most part the speeds were identical, occasionally + or - 1 kph. What I found interesting was that the distance was off by .50 km: 30.36km from the front/Sigma and 29.86km from the rear/Astrale. Both computers are set to values published in their respective manuals for my tire size (same front and rear). I can see where, when turning, particularly when turning tight, the rear wheel would track a shorter distance than the front, but I don't know that it would amount to 0.5km over that distance on this course.

Could it be just a calibration issue? Or maybe it's the way my front wheel spins when I come off the ground at the top of the hills .