Pine wrote on 05/24/12 at 09:59:33:I installed a bicycle speedo from Wally-world. It does not work. It seems the vibration from the bike causes the unit to register just any ole speed it wants. Once the bike is shut-off it will go back to zero, otherwise just random numbers, even sitting still. The clock works and it has indiglo backlight.. so I do have a workable clock. $20.
Sounds like you bought the "wireless" kind. Those don't work because of ignition noise, etc, etc.
Get the one with a wire from the sensor up to the display, and it should work OK (mine does).