I recommend the Sigma BC509 from REI. wired, $20, basic functions, which is all I need: current speed, time and distance since last reset, odometer, time-of-day. Unlike the entry-level wired Cateye, you can set the odometer during installation. Useful if you need to replace the battery or the entire unit. If going on a long tour and you really like having a computer, you might want to carry a spare, since bike computers can break, especially the wired ones (though I haven't had one break yet). At 45g, a spare BC509 doesn't weigh much.