This could only happen if you were traveling at sufficient speed (that is, +20mph,) with temperatures below 40ºF, and a suitable range of humidity. Frost above ambient freezing is a result of wind chill.

All of these conditions could be met with tights. Knee warmers provide absolutely no advantages in performance or convenience.

In this case, you are apparently so fast you need to have de-icing equipment installed, like aircraft.

Yes. Exactly those conditions. Frost on extremities due to wind chill, but because of the metabolic effort the core is quite warm and a double layer (tights over bibs) is uncomfortable. To me at least. But yes, you've perfectly described the conditions I'm talking about, which are very common in NorCal during the winter.

Very different conditions here in the inland desert. It's either wet or cold, but seldom both. Usually just hot, actually.

I also feel like I'm the only guy who owns "cycling bib tights," the kind with the chamois in them-- I don't layer, I just wear the tights.

I made "gators" of stretchy windblock fabric and Velco that wrap around my ankle under my tights and go over my boot tops or down to my shoe tops. (I wasn't thinking shoes when I made them or I would have run them longer.) I made them to keep water out of the boots but quickly found myself wearing them on most cold days, wet or dry. They keep my feet a lot warmer. I think not being waterproof helps with foot/sock smell. I'm using the 45North Fasterkatt boots and get regularly surprised how fresh my socks stay, even on days spent indoors wearing the boots.

Ben

Normally I just wear some hiking pants. The once where you can detach the legs. Keep the legs on on chilly mornings and take them off at warmer evenings. But when the temp gets closer to freezing or into subfreezing range I am going to wear some older cross country skiing pants I had still had lying around. And for my shoes I got me a pair of Pearl Izumi Elite shoe covers and they work great for me.

Practical and frugal!

Eep! I'm glad there's no risk of me going over 20 mph on my commute. Ever. I wonder what effect 90% humidity has on the frosting temp...?

It's wind speed, not ground speed.

^ ^ ^ Oh good. I only get wind in the afternoon, and if it's that cold, I'll take the bus.

<--- (weather weenie)

I think leg warmers over jeans look terrible. I wear long socks to keep warm. I used to skateboard in winter in thin jeans and didn't think about extra clothes to keep warm. I now admit that I was young and stupid. Because I made myself a problem with my legs due to hypothermia. I don't make these mistakes anymore and wear clothes for the season. By the way, I recently found a great blog where you can read a review about vegan skate shoes, if you are interested, you can find it on https://getvegan.com/. And I can say that these are the most comfortable shoes for skateboarding.