I geocache at times. It's fun with or without a bike. :-) I do recommend getting a real GPS though, something like the Garmin eTrex for instance. I've tried using my phone, and find it to be quite inaccurate in comparison to the eTrex. I was getting annoyed with it last week, and put the phone right next to the eTrex and had a 50 ft difference in location, with the eTrex being spot-on. You can use the phone, just be prepared to get frustrated or widen your search area!