When I was a kid, I loved working on my bike. It was a single-speed BMX, and I would put it together, take it apart, and tweak and tune it in-between. In the intervening years, my bikes have gotten more complex, but my repair skills haven’t kept up. Which is why I’m a fan of Atomic Software’s Bike Repair ($4). This universal app offers 58 repair guides, and 95 “tips and tricks” for fixing problems, keeping your bike in top riding shape, and even helping you avoid common injuries that stem from poor bike fit.