At 2°C, i used two sets of thermal underwear, ski socks and winter gloves to my regular leather jacket and pants. As long as the sun was shining, this combination was good for about an hour or so. I ended the season not because it's to cold, but because they will start soon to strew salt on the streets.
I ride as long as it is 50 degrees (F) or higher. I have an old (thick and heavy) Hein Gericke leather jacket, with a Gerbing battery powered heated vest, Olympia cordura overpants with liner, and Aerostich winter gloves. Keeps me toasty, with a smallish shield (cutdown slipstreamer on Dart brackets), and I keep an extra charged battery for the vest. They are good for about 1.5 hours each at 3/4 power. And my winter rides rarely go over 3 hours.
Check those tire pressures, too, they drop in colder temps.
I rode a week ago 3C but I am done. I wear glove liners, under armor top and bottom, 2 pairs of socks, balaclava, hoody and leather jacket. I found my new shark helmet warmer than the lanesplitter. Next year I may upgrade to heated gear
My winter riding takes place in Arizona. I trailer my bike there about December 27th and stay as long as I can, usually till about the first of April but it's still too damned cold for me in northern Michigan to ride much. I do have heated gloves for colder riding (12v from the bike's electrical system) but one thing is for sure, cold weather like we have here takes a lot of the fun out of riding.
Best trick for warm feet is to wear some thick MX style socks and a pair of tall Dual Sport boots without any big plastic chunks on them. The tall boot keeps shins warm with the padding. I have an old pair of Hi Point enduro boots from 1973 that I wear, riding down into the low thirties. Hands are a problem even with good gloves. Hand guards are a must to help that, heated grips the next trick. I've never tried the "Hippo hand" covers, if they are wind proof they'd do it.
I wore a Heine Gericke Boost Jacket for years, waterproof/wind proof, only flaw was a cold spot at the upper chest where the thermal lining didn't cover, the jacket liner was it. A good jacket is the trick though. I have some nerve damage that makes it hugely painful wearing long sleeves and barely tolerable with a coat, so my experience is with an insulated coat and short sleeve shirts riding into the 30°F / -1°C for a 50 mile commute one way (suffering for a 70°F/21°C ride home on a road known as one of the best technical rides, Ohio state route 164) and into the 20°F/-7°C range for a short commute.
I rode in cold temps year around, as low as 20°F/-7°C when I worked only 6 miles from home. In the afternoon when it was warmer I'd take the 12 mile fun ride home. Biggest problem was having the 650 single warm enough to start at the end of the day. One day I had to bring it in the plant to warm enough to spin over. It was usually worth it for the enjoyable ride home. Now where I am at it is flat and straight, I'll drive the truck and have a cup of coffee, more fun than riding that flat crap... although with the XSR it is more fun coming home, I found one of the very few good roads that gets me close to home with a bit of "roller coaster" riding.
I use heated gloves (Gerbing G12), the best invention ever, Daytona GTX boots, which are one size too big with "Woolpower 800 Socks", ski underwear with "Woolpower Full Zip jacket 400". When it's really cold I pull a "Woolpower Turleneck 400" underneath. Then my Stadler textile suit comes over it.
And when it gets even colder, I pull my original Thermoboy, which I bought from Helmut Dähne (record holder on the Nordschleife for years), over it.
Since "winter" means 12°C and sunshine in south germany right now, i removed all unnecessary layers and rode a few hours today in my standard outfit, leather jacket, cevlar jeans and three season gloves.
I bought Wells Lamont leather gloves for riding. These are some of the toughest ones I've used, and I've use a lot. The leather is very soft and the tightening strap is a nice feature. Yes, they were tight on my hands to begin with, but they stretched nicely and are now like a second skin.
I ride when the outside temps down to mid-high 30s up in the mountains but I don’t like to ride any colder than that. Have had some sketchy cold tire/road icing issues and I’m done chancing it. The big thing is preventing air from touching any of your bare skin especially on your neck, hands, ankles. I stop every so often to warm my hands and get some blood flow through them. I’m looking at handguards to take some of the wind off, hopeful it will help. The windshield just increased buffeting.
Thermal compression gear on top and bottom.
Long sleeve shirt over that.
Heavy leather jacket with insulation.
Heavy leather riding bottoms
**heavy neck scarf cover thing to cover my neck. This one is important.
heavy leather riding gloves with latex gloves underneath.
Either heavy leather full engineer boots with thermal socks or full riding boots, either way the riding leathers are tucked in.
That’s pretty much it. Nothing really very special. The thermal compression gear is incredible. I use the”32 degrees” gear from Costco.
Nofel Winter Cycling Lobster Gloves, Hi-VIZ, M aximizes finger dexterity for shifting and braking of Bike. The multiple spots of silicon on the palm keep the optimal grip for the rider. Synthetic Leather provide softness feel on palm.
I ride all year-long, except on snowy days (extremely rare). I have heated gloves, Racer Heat 4 (I had the Heat 3 before). And the previous owner of my XSR had heated grips installed. I haven't tested them during winter yet, but I did in April, with summer gloves, and it was very comfy!
For the rest, if I do an actual ride (not just a work commute), I can wear mountaineering clothes (pants + long sleeves shirt), + waterproof over pants if needed.