Originally Posted by
dougmc
I'm sorry you're so strongly against this method of calibrating your cyclocomputer, but it's a perfectly valid and extremely accurate method and very easy to do.
You haven't presented any support that it is
any better than other methods!
Originally Posted by
dougmc
It's no more complicated than trying to measure how far your bike goes in three revolutions of the wheel -- and more accurate. Three revolutions worth of tire rotations works out to about 248 inches for 700c tires. Most tape measures aren't that long, so you'll have to measure out a few times and make marks.
Why "three revolutions"?
Originally Posted by
dougmc
I'd estimate the error when all done at around 3" or so? If so, that's a bit over 1% error -- which is certainly acceptable,
You argument is based on
guesses!
Originally Posted by
dougmc
but a GPS could easily do 2 or 3 times better over a mile or two.
And the path that the bicycle takes
is likely going to be longer than the accurate path the GPS measures. Bicycles wobble all the time.
Originally Posted by
dougmc
That said, all of the ideas given in this thread are good enough and can get you within a few percent even without even being that careful -- and that's probably just fine for 99% of the people out there. And if you're careful, you can get within 1% with most of the ideas here -- and that's close enough that small changes in tires, tire pressure or load will probably introduce larger errors than that.
And here you present the reasons why the GPS method is overkill!