I've had my bike going 500+ mph, at least according to my Garmin. My CatEye said 12 mph at the time, and since this was on a crowded section of MUP going across a bridge, I don't think I was going about the speed of a Boeing jet. Another time, my Garmin said I rode my bike from Seattle to China and back in about ten minutes. I must have had a lot of air in my tires. ( In short, Garmins are unreliable, and if common sense ever tells you not to trust your Garmin, it's common sense you should believe. )
Originally Posted by
tntyz
How far off was the max speed reported by the unit v. Training Center? I sometime get the same thing using Sport Tracks, but the difference is small (0.1 mph). The application may actually recalcuate speed based on GPS information and the algorithms used may differ slightly. Just speculation on my part.
They both use the same math to calculate your speed, but SportTracks "smooths out" the data before applying the speed formula.