For a cheap wired unit I'm pleased with my Nashbar Tempo Cadence Bike Computer. http://www.nashbar.com/bikes/Product...3#ReviewHeader For $20 you can't beat the price. It is a wired unit with two sensors. One on the rear wheel for speed and distance and one on the crank for cadence. Some of the reviews are negative, but other than a loose battery contact on mine (described in my review on the Nashbar site) I haven't had any problem with mine, and I ride some pretty rough roads.

Jim