Quote Originally Posted by nc23
Second, where does the policy of not wearing underwear with bike shorts come from? Word of mouth? Both of us have been wearing underwear with bike shorts for years. It isn't ideal, but I'm not sure that no underwear is ideal either.
As others said: chafing is the major issue.

Second: bike short chamois is actually more hygienic for exercise than underwear. It manages perspiration (and my inner legs sweat A LOT during cycling), and is usually treated to be antibacterial. By adding another layer of fabric (especially cotton) between yourself and the chamois you actually diminish its capacity to wick perspiration away.

I know some people wear underwear under their shorts, but I think it totally defeats the purpose of getting shorts in the first place. I don't need the padding as much as I need to avoid anything causing friction between myself and the saddle.