Originally Posted by diverguy

I use the iPhone 4 in a handlebar bracket running MotionX GPS software. Works great. Using sites like RideWithGPS, MapMyRide or one of the many others, you can preplan your routes and export them as gpx files to your computer. They can then be imported to MotionX GPS so you can overlay them on the map and follow the preplanned route. The app tracks your time, distance, current, average, and maximum speed, altitude, descent/ascent rate, etc. Cheap - $2.99.