"robgraham" wrote in message
...
The distance that my bike computer is measuring is not in agreement
with what I plot out on Google Earth.

Yes, it's pretty obvious that that depends on how well the path is
traced on GE, and on the setting of the wheel size into the computer.
So taking those out of the equation, given a careful plotting of a
calibration road distance of 4.0 miles on GE, what is the accuracy of
their 'Path' measuring system?

The alternative question is how does one get a reliable distance to
obtain a calibration.

I've just had an argument with myself as to whether I increase the
wheel calibration figure or reduce it to compensate for the 5% high
error I'm getting on the 4.0 miles, and have won the argument by
realising that the entered circumference is the multiplier for each
pulse from the sensor, so counter intuitively (initially to me anyway)
to reduce an over-mileage, you reduce the computer wheel calibration
figure.


Using Google Earth is not going to give accurate figures. Probably the way
to do it is to use a GPS and measure two marks on a length of road and then
check to odometer against it.


Peter Crosland