I'm in Minnesota so if I didn't ride when it was cold, that would knock out of a number of months I could ride. I typically will be on the road bike starting in the middle of March and continue on through the beginning of December. That means low temps in the 20's but the piece that is the the determining factor for me is whether there is ice or not. That means, here, that the ground is not frozen in the fall and then that's bounded first by the road not having ice and then by getting the salt off the road in the spring so I don't destroy my bikes. In the intervening time, I'm usually skiing and riding my fat bike. I'll ride the fatbike down to -5F depending on the windchill. Below that, it just gets to be too much work getting dressed and I'd rather be skiing anyhow (my other obsession).
The biggest issue for me is clothes. It is really tricky to get it right and I seem to be overheating of freezing if I'm not careful. It has gotten to the point that I've created a spreadsheet of temps vs clothing to wear and I refer to that whenever the temp is 55F or lower, it seems. I've also found
a source to make clothing to my specification and that has really been helpful. I have a jacket that's neoshell in the front and highly breathable power stretch in the back to shed heat. I also have tights made out of heavyweight power stretch that breath very well but are virtually windproof. Those work great from freezing down to -10F.
Gloves in a layered system and feet are the big issues for me and I've spent a fortune on both until I got to some solutions that work well. I have
winter road shoes and
mtb boots that are both amazing. Otherwise, for clothing layering is key and it seems to me that on top its some combination of
thermal jersey, a wicking base layer that's either
light weight or
medium weight thermal. A very key piece of clothing for me that gets used in a wide range of temperatures is this
windproof thermal chest protector I get from Warmfront. Add to all of that a collection of knee and arm warmers that can be work under winter specific tights and my only excuse for not riding is laziness.
As far as being outside in cold temps - I haven't seen a temp too low yet for me to be out in. Every year, it seems I wind up skiing at or near -30F. It's not a matter of too cold it's a case of improper clothing.
I stud the tires on my fat bike. They work great and I've never ever felt like they were going to slip out from underneath me. I also have studded MTB tires, and they're solid too, but not anywhere near as sure footed at the fat bike tires are. A fat bike with studded tires is the cycling equivalent of a monster truck. If you have the legs and the cardio, there is pretty much nothing you can't ride in. I typically ride snow packed trails, slushy roads, frozen lakes and even on a long sand beach
J.