On Fri, 30 Sep 2011 06:50:11 -0700 (PDT), robgraham
wrote:

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?

You've got answers on the bike computer side...

GE will squish and stretch the photos to form one image. This will lead to
errors, some obvious like objects at the edges having two shadows.

I have found GPS coordinates of single points I've marked in the field to be
fairly close in North-South direction, and to be off by up to 50 meters or so in
East-West. Don't know if that's a local effect, or generally so.


Thomas Prufer