it depends on the purpose of the ride. on my road bike--when I go for long rides, i wear your basic road outfit--lycra shorts, jersey, road shoes (look pedals); water bottles. If I am just running a quick errand and my commuter is out of commission--I wear regular clothes and sneakers (the pedals are big enough to support my reg. shoes).

on my mtn bike: lycra shorts (same problem others have had--mtn bike shorts get caught on the saddle); mtn bike shoes (time atac set-up); same jerseys as road; same helmet; camelback type set-up(brand name: "source" out of Isreal);

on commuter: lycra under baggy shorts; mtn bike shoes (time atac pedals); baggy t-shirt. I try to be comfortable.