I love building/working on bikes.

In the past few weeks, I have overhauled the BB, hub, and headset of my commuter bike. Now, whenever I ride I can just envision exactly what is going on. I can imagine the BB spindle turning inside the bearings, picture the way the stem is wedged into the steerer tube, and practically feel the tightness/looseness of my hub.

Also, to be honest, I'm a better mechanic that most the guys who work at the shops, so I just like knowing that my bike isn't going to fall apart.

I work on anything that I can. I work on cars, dirt bikes, jet skis, bikes, etc. I would work on my own house if I had one. I'm just a grease monkey, I guess.

There is that element of immediate gratification w/ bikes, though. Everything else i've worked on takes much longer and is much more expensive. With bikes, I can do an entire build in one day for <$600. Shoot, the rear view mirror on some vintage cars costs that much alone!