Jasper Janssen said:Quoted message said:For the fuss and trouble, consider spending $10, including
tax, at WalMart for a Schwinn cyclocomputer with battery and
instructions. It's as ridiculously accurate as any ordinary
cyclocomputer.
Is that the one where you set the wheel size as circumference in inches,
rounded to the nearest inch? Cause that sounds inaccurate.
Jasper
Dear Jasper,
No, that's the one whose speedometer reads in thousandths,
not hundredths of a mile, and is calibrated in millimeters.
The basic technology for a wired cyclocomputer is about as
complicated as a digital watch (invariably included), which
is why a $10 model is likely to be just as accurate as an
expensive one.
Increasing the display resolution to thousandths of a mile
illustrates how basic the features are. Strictly speaking,
5.280 feet is a touch less than a typical wheel revolution,
but it's trivial to force the display to turn over whenever
the total wheel revolutions divided by 5.280 feet break the
next integer.
Accuracy to 4-digits (millimeters) is hardly asking much of
a computer circuit.
As for practical matters, the handlebar mount is nicer than
most of the $20 Nashbar and Performance mounts that I've
used and the seating of the computer on the mount adds a
latch to the usual push-in system that eventually weakens
and lets the contacts occasionally disconnect.
And in any case, the nearest inch is still ridiculously
accurate, despite your assumption. For a 700c tire, the
industry suggests 2124 mm, or 83.62 inches. Rounding that up
to 84.0 inches would lead to a mileage reading that was a
whopping 0.45% high.
Carl Fogel
