Re: Why I don't trust mechanical speedometers.
I have one of the schwinn 10 dollar ones from wally world. you calibrate the wheel size when you
first put in the battery. I used old tire tubes on the mount to lessen vibration, just like my motor mounts. vibration hasn't killed it (yet), and it is definitely accurate according to the speed trap thingeys on the side of the road as well as my little ladies car.