GPS receivers are now made waterproof, lightweight and small enough to fit on a bike easily. There are 2 basic choices to take on your bike: a GPS unit designed primarily for navigation with a dedicated bike mount, particularly suitable for cycle touring and finding your way in unfamiliar territory, like the Garmin eTrex ; or a dedicated bike computer that uses GPS to track your training routes and provide detailed analysis of your workout like the Edge 305, with more limited navigation capabilities. Most units come with only very basic maps installed and you may need to purchase more detailed maps for your area to be loaded onto the unit for navigation.