I too went for years following the rule Never Ride With Underwear.

Last year I discovered that I can wear my seamless Patagonia Active Hipster underwear under bike shorts, with no detriment. (In fact, that is how I do touring now...Instead of washing the shorts every single day, I can just switch out the underwear.)

In conclusion: The No Underwear Rule was written by/for men...who maybe do not have some of the nice seamless undie options that we do

- Mariposa