Dumb Computer Question

[Pedal Wench]

And my dumb computer question is: are there bike mileage-measuring computers that don't need a wire that has to run back to the rear wheel?

Actually, most wired computers use the front wheel, so you only need a cable running down the front fork. Only if you want cadence, or the ability to record speed on a trainer do you need to run the cables to the rear of the bike.