So I live in one of most bike-friendly cities in the US. Easy-to-access trails go all across our city, including a new one that just went in this summer that goes within a couple blocks of our house. I've used the trails a lot for running (pushing the jogging stroller), but I hadn't biked during the whole time we've lived here. In fact, I don't think I'd biked since my son was born, back when we lived in Michigan (and Dearborn is not a bike-friendly city).
But I love biking. So this past week I finally pulled my bike from the little space where I keep the lawnmower and other yard tools to see what kind of work it might need. Pumped up the tires, WD-40ed the chain and gears. It's an old bike. I bought it used when I was about 10. But my cousin owned a bike shop, and he sold me a very high-quality touring bike. So it's served me well. In college it was stolen (because of a faulty bike chain) and recovered months later in the basement of a different dorm, minus a seat.
And yesterday morning, before anyone else was up, I took it for a ride. It still needs some work. I can shift between most gears, but if I go down into gears 1-5, I can't shift back up to 6-10 without getting off the bike and manually moving the chain over. But I seldom use those lower gears anyway, and wow, it was so good to be able to bike again. And with the new trail, I could easily get to the opposite side of the city and back. Now we just need a trailer for my son, and we can explore much farther than we can running.
Oh, and this is what I discovered for myself right now. I'm in pretty good shape from running. The running I do is somewhat of a muscular workout, but mostly it's a cardiovascular workout. Biking is the opposite. I could have gone much farther and faster without bothering my heart or lungs much...but my legs were dead.
So, go biking!