I've started riding my bike for a few days and have a couple of questions mostly regarding accessories.

1. What do you guys use to lock your bikes? I have a cable lock right now but with a brand new $700 bike, I'm a little worried about how easy it would be to cut a cable lock. On the other hand a U-Lock might be heavy and I don't know if I want to carry it around (might have to though - just interested what you guys do)

2. Lights - on days that I have been riding, I've been getting in to work later and leaving later because the sun still isn't up early enough. Any advice about lights that people have? Do I need a front and rear light or will a reflector on the back work? Any advice about being visible right before sunrise would be great.

3. Tubes - been looking to find some spare tubes online - I have 700 x 28c tires. I see online 700 x 20/28 tubes and 700 x 28/36 tubes......which ones do I get?

Thanks for your help!