I use my gps on my bike - it was originally purchased for kayaking, but I just shove it into my pack while biking. I do have bike computers, I've just been too lazy to hook them up. I do have a heart rate monitor, which I ride with every so often to get an idea of how much effort corresponds to what heart rate - but doing that once a season is usually a good marker.

Thread hijack - since it looks like you live near lake superior and kayak - what do you recommend? I'm planning on heading up there for a week this summer with kayaks and want to kayak tour/camp. Is there much of a water temperature difference between June and August and what should i not miss? I'm just starting to research, so so far I've only really touched on pictured rocks and the apostle islands.