Bicycles are alright, but I don’t understand the lycra. Seeing men in that stuff is like seeing them in ballet outfits.
You see, I’m on a remote part of the Rockies. Most of the year, something like traditional Mongolian clothing would probably be best (but with better boots and goggles—frequent high winds, spraying ice and way below zero).
The nearest highways are two lanes with no shoulders, many blind curves, hills and 65 mph speed limit. Packs of summer bicyclers make those roads extremely dangerous for everyone near them. Elevations 9,000 to over 11,000 feet, too. The temperature can drop from 65 F to 35 F or less within minutes during summer, when storms come through.
Most of them are tourists in groups. The passes are even worse. But where you’re at, the situation is probably very different from the situation here.
Friction and chafing, primarily. Aerodynamics too, not that any of the ones we’d likely encounter will ever participate in the Tour De France though, lol. But, their idols wear it and it does prevent painful aftereffects, particularly for males.