Originally Posted by
Mr. Fly
However, as you said so yourself (underlined), there are fluctuations in GPS units that introduce significant errors when measuring small distances. These small errors, when added up, will give you a larger error than the tiny 0.3% error (estimated in my last post) of a conventional cyclocomputer.
As I said, you can measure the approximate amount of error introduced by just letting the unit sit in place for an hour. An hour at, say, 20mph in 105,600. If you have 400 feet registered in that hour (about what I have observed), that is .3% as well. So the error amount is similar.