Originally Posted by
HD3andMe
From a max speed standpoint the accuracy difference between GPS and the wheel sensor is interesting.
Yesterday my kid slapped one of my speed sensors on his mountain bike. Entered the circumference of the tire, while weighted.
Strava, which disregards speed sensor data, showed 49 mph top speed. Garmin Connect, which reflects speed sensor data, showed 50.9mph.
The faster one goes (and more importantly, the faster one accelerates/decelerates) the more pronounced this effect becomes.
My favorite speed run around is about 1/2 mile straight with a 50 mph speed limit that I always exceed.
I typically hit speeds in the mid 60s as indicated by my wired wheel sensor, whereas the GPS (on a phone no less) rarely goes above 49-52. The wierd thing is, I can hold 65-68 mph for at least a couple yards of that run, but the GPS still lags enough that it 'smooths' out that top speed quite a bit. On my more normal routes, the smoothing is much less noticeable, usually within 3-4 mph peak.