My dh uses a smartphone application for geocaching which works great. I have a Garmin Dakota that I use for geocaching, and I recently realised that I could just put it in a pocket and take it on the bike too. It doesn't give me cadence etc but does record where I went, max/avge speed, altitude etc, I can upload it into mygarmin and get all proudly geeky at the combination of cycling and IT skills. I wish I'd had something similar in my fell-running days.