Three-fourths of my rides and over half of my mileage is from commuting. Why do all of that riding on a crappy bike? I commute on very nice bikes but have a safe place to park them at work with security cameras, a Kryptonite NY lock and cable. If someone steals my bike so be it, but I am willing to take that risk so I can ride a nice bike. However, everyone's situation is different. If I worked somewhere that was a theft hotbed with no secure place to lock my bikes, I would probably ride a beater as well.