Originally Posted by
plumberroy
I down loaded urban biker app this week I have made one ride with it . The cheap ( schwinn ) Wired computer on my bike showed 16.4 phone showed 16 miles I am guessing the gps will be closer to the Actually mileage
How do you know the 16.4 miles is correct?
GPS may show a slightly lower distance than a correctly calibrated wheel rotation counter since the counter is including every wobble (you aren't riding in a straight line). You can also lose GPS reception (which will tend to lower the measured distance).
Counting wheel rotations is easy to do (wired is nice and simple). Being cheap isn't any problem. The issue is using an accurate wheel circumference.
GPS is still very good and good enough.