Originally Posted by
tomato coupe
The distance error of a wired computer accumulates (linearly) as the distance increases, however, giving a GPS-based computer the advantage at long distances because GPS positional errors do not accumulate linearly.
This is what I thought your reasoning would be, but I didn't want just assume it. It's a mistake IMO. Distance actually travelled is the length of the actual path, not the difference between the end points. It's actually the GPS that accumulates errors linearly, because 1) it disregards small path variations, and 2) errors in an instant's position result in fictional movements. The second depends on the programming of the GPS of course, but you can see that it's true by examining the GPS track.
In contrast, there is no accumulated error from the wired bike computer other than calibration. That error is, as you implied, linear with respect to the total line distance. If it's off by .1% for instance, the entire distance is off by .1%. I'm not sure if that's what you meant by "accumulated linear error" (to me that implies a linear error accumulated geometrically)
4) If a GPS-based computer is used with a speed sensor, there's no reason it couldn't measure distance as well as a wired computer at short distances, but I don't know if they use speed sensor data when they calculate distance.
I submit that using the wired wheel sensor on a GPS is not technically different than a using a wired wheel sensor on a bike computer. That it improves distance and speed calculations indicates to me that it generally is used for that purpose, and that the wired sensor is superior in accuracy and precision.