There are times when you really need a cycling cap. Like, actually need one: to protect your eyes while you squint away the road spray kicked up from the wheel in front of you; to keep at least some of the rainwater from running down your face into your mouth. I've got the image of a grime-coated rouleur pound out the cobbles in a Spring Classic. Cap under his helmet, bill down.
If that laboring hardman is lucky the rain stops and the sun comes out. He wants to feel the sun on his face. Flips that bill up. It was easier in the days of "hair-net" helmets, but the thought counts.
If you forget which bill orientation you should use when, we've made it easy:
Flip up for sun. Flip down for rain.
Of course, caps aren't just for under-helmet use. Properly wearing a cap is an art in itself. Not just an art... a sign of your commitment to #rodielyfe. Are you the kind of rider who will risk ridicule by 99 out of 100 people who see you so you can prove your tribal affiliation? Flip that bill up. That's right. I'm 6 feet tall, 135 pounds and I wear a cycling cap with the bill flipped up. I'm living the #rodielyfe.
Remember, however and whenever and ifever (I just made that up) you decide to wear a cap, always be you.