I’ve done many -20 C rides.
I live in Colorado and it gets real cold during winter. I don’t go out riding if there is snow but if it’s just cold, go out and ride.
One with the environment
Ride at any temperature. I regularly ride at -60…it’s a great way to bond with the Eskimo, the polar bear, walrus, and narwhale.
As soon as it becomes feasible I plan to unicycle on the Sun. I know that will be very hot unicycling on the Sun so I plan to land at night and keep the visit short.
This is a great thread.
BTW, the doctor say’s my getting phenomenally 
sick with pneumonia was just a bad bug, nothing to do with riding in the cold. I think I was exhaused from my work duties, and the cold riding was just additional stress to help the sickness get a deep root.
Reading this tread and thinking back, I will improve by wearing hiking boots this year. Last year I wore sneakers. It wasn’t at all cold during the 4-5 mile ride, but as soon as I stopped, the soles of my feet would get very cold.
Here in Western Canada winter temperatures of -30c (-20 f) & -40c (-40f) are not unusual. This morning its -32c with a wind which is making it -41c.
I cycle year round for transportation and have used my unicycle at these temperatures as well.
I’m not suggesting that its any fun, just letting you know that you can do it.
Proper clothing is of great assistance in making your ride a bit more pleasurable. Most people tend to overdress and will quikly overheat as most riding done at these colder temperatures tends to be strenuous. (Stiffer cranks and possible snow resistance.)
Experiment with your clothing needs and you will come up with combo’s that work for you.
You won’t know until you try it, so give it a go and at least then you can say you did it.
I hadn’t meant to imply that riding in the cold actually causes illness 
It just, as you said, may cause additional stress that may prevent your immune system from quickly eliminating it. More orange juice! 
-14degC last winter for me and no problem !
If your testicles are freezing to the seat, its too cold.
Read this thread from Captain Welch about his Alaska ride in 2008, and then make your mind up.
If you don’t ride now, expect to be called a sissy 
STM
I’ve never ridden when it was colder than, say, 10c. But then again I usually try to avoid leaving my house if it gets much colder than -20c; I really, really don’t like the cold.
The ride report (yes, of course I rode!)
Thanks everyone for the great comments! I was probably inclined to give it a go in the first place, or I wouldn’t have made the thread, but the encouragement really locked in my resolve. So last night I decided to commit to riding this morning regardless of the temperature, and I got all my various gear together.
The weather this morning turned out to be a bit disappointing, but I suppose in a good way. 16F, within my usual recreational temperature limits. So I rode, and had a great time. The disappointment is that I didn’t really end up pushing my limits, so I’ll just have to keep an eye out for that opportunity later.
I did have a couple “firsts” this morning. First time riding any distance on the WTB Stout. Took noticeably more effort than my 2" Big Apple (I ride a 29). But I need the traction for the snowy bits, so I’ll keep it on, even for road riding, through the winter.
The other first was my first unanticipated sideways skid on ice without a upd. From my point of view I slid sideways about 2-3 feet before catching it and smoothly riding away. From anyone else’s point of view is was probably more like an inch. Nonetheless, I’m kindof proud of that one.
I agree with the comments about the importance of good gear. I’ve got a number of years of experience doing search & rescue in western Montana, so I’ve been able to build up a decent collection of gear and have tried out enough combinations to get it dialed in pretty well. For the 16F ride, I went with a thin helmet liner, started with goggles (but took them off pretty quick; there was no wind), fleece neck gaitor pulled up over my mouth, fleece vest over a long sleeve mid-weight synthetic long underware shirt, light fleece golves that fit under my wrist guards, my usual work pants (thin cotton-nylon blend khaki’s), knee-high wool ski socks, and gore-tex mid-height hiking boots. Small backpack for work clothes also keeps my back a little warmer. I also carry a windbreaker, but I hardly ever use it if I keep moving. At the beginning of the ride my fingers were a little cold, and at the end of the ride my head was a bit hot - so I figure I got it about right.
So the bottom line for me is that 16F is certainly not too cold to ride. I’ll have to find out about 5F some other time, but I am inclined to give it a try. 
Glad you went for the ride. I just went for a ride yesterday in the first good snowfall we had all year.
I would say that there is no temperature that is too cold but to tell the truth I ended up not going on a couple rides this month due to weather. I figured it probably would not be smart to go out when it was -30 and windy starting to get dark and the temperature dropping on untraveled and partially unmapped trails. My current setup is about perfect for -25ish
Urban rides are a different story. The coldest I have ever ridden in was the blizzard in 2007. It was -45˚C with estimated wind-chill of -80˚C (thats -112F!). My truck would not start so I unicycled the 4km to class On my way home I dropped the unicycle and my handle shattered. I was properly dressed and the only part of me that got slightly cold was the fingers of my right hand (the one that holds the seat handle).
If it is calm and sunny out I can comfortably ride or run in -15 with no shirt.
A great tip for winter unicycling rides is to use the smallest backpack you can fit all your gear in with a camel-pack and wear it under your shell/top layer. Your body heat will keep the water liquid but you still need to drink fairly regularly to keep the hose and mouthpiece from freezing solid. I also have a insulated hose on my waterblader which helps a lot.
Actually, I thought that I implied that cold weather riding caused illness. 
+1. I’ve actually got a really small camelback expressly designed for wearing under a jacket. But it’s only good in a ski area, as it does not carry gear. I have also bitten through the drinking valve before, in an attempt to crush the ice to get some water. Now I use an insulated hose, with a big rubber cover for the valve. Although I’ll admit that today I took the lazy route of just bringing a bicycle water bottle. Worked OK because I wasn’t out that long, although the valve did freeze up a bit.
I always trusted real cold
I live tropical now, but I was raised in CT. We didn’t have any fancy Gore Tex like waterproof stuff then. Just big fluffy non waterproof stuff.
The most dangerous cold in those days was the 30’s F. As long as you knew it wasn’t gonna rain, like 0-30 F, all you needed was a puffy nylon coat. I always felt really relaxed when it was really cold. It was dry, and gonna stay that way. It was when that cold rain came down and soaked my jacket that I froze.
I had a similar experience only a couple days ago. I was riding my Coker back from work and mistakenly thought I could make it through a pile of snow on the sidewalk. I fell, my uni fell, and the bar end on my pi bar hit the ground and broke. I don’t feel like it would have broken had it not been so cold out. Is there any credence to this claim?
One of the two items that I requested for Christmas this year was a balaclava. I’m hoping that I can use it when I commute to college throughout the winter. I’ve been riding without any form of head-warming gear for the past month, and although it has been uncomfortable at times, it does not deter me from riding. With enough clothing (ie thermal underwear, wool socks, warm coats, etc) nearly any temperature is rideable.
Saskachewanian, on the other hand, must either have a few screws loose for riding in -45˚C, or is part woolly mammoth. Personally, I’d probably draw a line around -25˚C (-13˚F) for safety reasons. I do agree with the general consensus, though… push your limits!
It is too cold to ride, when you don’t think it is fun to ride because of the cold.
I like to take this idea one step further (perhaps you do this as well) and fill the Camelbak with hot water. Makes you warm all over As one might expect, this trick doesn’t help with the frozen tube issue.
Hehe…
Well, for us arizonians, 15 degrees is unnatural. The weather we’re seeing out here is about 60’s ( at night time)… Winters my favorite time of year thanks to our oh so welcoming 120’s during the summer
My 2 cents
I live in the Chicago area. When riding in Winter I always carry extra warm weather gear in a backpack or big fanny pack. I don’t need it while I’m riding, but have it for when I stop and am waiting in the cold for the train. That’s when I think I could get hypothermia, especially if I’m sweating some.