Right, the 1.8C difference is substantial in terms of human physiology and indicates a diminished level of comfort as the body fights to keep the temperature up.
I also found it funny how they mentioned that modern clothing keeps you warmer longer once you stop moving, then tried to minimize the significance of that. There's a reason "cotton kills" is a cliche. Modern fabrics, windbreaker shells, and engineered layers don't make a huge difference in warm, dry, active conditions - it's when things go sideways that they can be the difference between comfort and fatal hypothermia.
There are times when layering is not the way to go. One of them is heavy activity in extreme cold. Layers can cause moisture to freeze in bad places. Having lived in a place that often got down to -40, I was always most comfortable with a light synthetic shirt under a single winter coat. No complex layers. And waterproofing isn't needed as there isn't any water around.
I also and have gone to -46F and for me a thick wool sweater and wool felt coat makes huge difference. I can not even wear my wool sweater until it gets to -20F otherwise I will burn up :)
My record was -63f/-53c. But it isnt all that bad. There is literally no weather/wind below about -40. No snow. No wind. No clouds. Only strange stuff like ice crystals falling from a clear sku, and snow that squeeks like walking on styrofoam. -35 and windy always felt colder than -50.
I know someone who has three or four different thicknesses of pure lambswool jerseys for wearing while he's cycling, at different air temperatures. It never really gets all that cold down south here at 56°N and frankly I think spending ten minutes dicking about over which jumper you're wearing for optimal performance takes a lot of the fun out of it.
That said, I'm a fat 52-year-old, and I cycle in jeans and a T-shirt, and if I start to feel cold it's a sign I'm not pedalling hard enough and I should get the boot down a bit, burn some calories.
Does it take 10 minutes to choose? Back when I was commuting, I had different kit depending on the temperature, and it wasn't exactly hard.
>50F: Summer gear, and not much of it. I run hot, and there's no need to make it worse.
>20F: Add a thick sweatshirt and gloves
>0F: Add wool socks, long pants and a wool underlayer, a windproof outer shell, glasses, a hat, a thicker windproof layer over my gloves, and sometimes a scarf depending on how short I'd cut my beard.
>-20F: Similar, but with some extra layers over my core, and the scarf is mandatory.
>-40: Similar, more layers.
<-40: I know my limits. I've nearly gotten in serious trouble before when it's too cold out and I didn't plan for extra wind and a cold pocket near the river or having to walk because of a poorly maintained road or whatever. My gear wasn't especially high-tech, and I just called work and emailed my professors to let them know I wasn't going to make it.
Wind would have me reaching for wind breaking and insulation at higher temperatures.
It wasn't a 10-minute process by any means though. I'd pull out my phone in the wee hours of morning, see that it was X temperature on the homescreen, and plan accordingly. If he's just selecting between a few jerseys that should be even easier, right?
I didn't have a lot of choice. I was pretty broke and also couldn't afford to skip 2 months of work or school. Nowadays I'm a bit more careful with my time.
If you start doing longer rides you learn there are general temperature ranges and kit that's fine to commute in or ride an hour in traffic with a rucksack is very different from the kit you want on a 6 hour ride in the countryside. I generally have kit for 0-10, 10-15, 15-22, 22+°C. My 0-10 jersey will boil me alive after an hour cycling in 13°C but likewise my 10-15°C will risk hypothermia in 8°C. There's only so much layering you can do with cycling kit before it starts becoming restrictive.
At one point I was stationed at a military base in the north which got to -40, even -50 somewhat regularly in the winter. Part of the orders for extreme cold was "no bicycles". Too many cardio nuts were seen riding in inadequate clothing, especially lack of proper boots. The worry wasn't them getting cold, it was them falling.
A light jacket is all good when you are pumping out the calories, but take a fall and you are now sitting on the ground unable to move. At -40 you may have only minutes before life-altering cold injuries (lost toes). Add to that the darkness and snowbanks and you might not be found for hours... IF anyone is actually looking for you. Cellphone screen get tricky in serious cold. A person walking to work, which was still not advisable, would at least be wearing clothing warm enough to stand still in the cold.
The radio used to have public service announcements calling for people to keep blankets in their car. Not in the trunk. Within reach of the driver. Get into a wreck, trapped without heat, and that fleece blanket under your seat might save your life.
Much further north. I was working with the canadians. I saw weather phenomena that i have seen nowhere else, from sun dogs every morning to watching the northern lights and realizing they are actually in the southern sky.
I'm curious: I do cycle in jeans and a t-shirt while in the city. Up to 45 minutes I'm perfectly fine, but if I'm on the saddle for over one hour I really start to miss the chamois. What's your experience with that?
Seconded. Old-school leather saddles are pretty good for riding in street clothes. But, they do tend to require a slightly different fit - I never managed to run one with my normal saddle-bar drop - the Brookes really wanted saddle and bar at the same height and the nose of the saddle pointed up a bit. This was good for ~2 hours or so, never tried it for longer, since I had normal road bike with normal saddle for that.
My old bike had a Brooks saddle and I gave it to someone to use with no real expectation of getting it back, and sure enough I didn't get it back. They're still using it though :-)
I wish I'd swapped out the really nice saddle for a more entry-level one though.
I also found it funny how they mentioned that modern clothing keeps you warmer longer once you stop moving, then tried to minimize the significance of that. There's a reason "cotton kills" is a cliche. Modern fabrics, windbreaker shells, and engineered layers don't make a huge difference in warm, dry, active conditions - it's when things go sideways that they can be the difference between comfort and fatal hypothermia.