My bike leans to the right. What should I check? The bike I use to commute - a cheap, no brand city bike - is unbalanced, and naturally leans to the right. This is not noticeable normally, but it's enough to make riding without the hands on the bars requires quite some effort to avoid drifting right.

Of course I can't just ask you what the cause is, but could you help me in finding it? What should I look for/test/check?
a) Is the headset tight? Over time that can loosen up and it'll start to lean in one direction or the other (usually based on which side of the pothole you just hit).

b) Are your wheels true? this probably won't make a major difference but it might combine with the previous point.

c) Is the weight on the bicycle evenly distributed? E.g., do you wear a messenger bag across your left shoulder so the weight of the load pulls the bike in that direction?

d) Does this happen in a parking lot as well as on the road? Don't forget that streets aren't flat - they curve off to the edges to allow water to shed from the roadway (and into nice deep puddles for motorists to drive through and splash cyclists). If it only happens on the road (and you always ride on the right hand side of the road) it's probably because of Gra-vi-ty.