Last week I got a Delphi bike computer for my Trek 1.5, and installed it myself. The ride mileage and average speed seem fine, but the MPH reading jumps aroud a lot. When I am peddling on the flat under 20 MPH, it seems fine, but If I accellerare or go over 20, the reading jumps back and forth from around 10 to 20 or so. If I stop pedalling and coast, the MPH sometimes steadies out. Worst of all, when I go over 25, the readout sometimes just shows zero!
Any ideas? Maybe I should have spent more than $30, but all I really care about is tracking mileage and knowing reliably how fast I am going.