this is not an endorsement of a product, but all the 305 series Garmin EDGE are GPS-enabled cycling computers with a temperature compensated barometric altimeter.The lower priced EDGE 205 doesn't have a barometric altimeter and relies on GPS for the altitude reading.

If you get the Edge WITH cadence you also get a wireless speed/cadence sensor. you can also get it with heart monitor functions, or both heart rate and cadence.

it does not let you look at nice maps on the screen although it does do waypoint nav as well as offer post ride downloads that let you extrapolate your rides on maps via your computer.

it is primarily a tool for training and etc, designed first and foremost as a cycling computer.