Also, the foot muscles don't get much exercise while cycling so that limits warming circulation vs while walking or running. Feet & esp toes can swell during cold, I read that some cold-weather bikers emphasize having a roomy shoe though I'm sure rhm has already thought about that. OTOH due to hard-to-fit feet I've been dealing w/inadequate winter footwear for decades so I'm semi-immune to the cold. Cold-numbed feet aren't fun but unless conditions are pretty terrible one won't get frostbite.

Well anyway I look now at posts about electric socks & chemical foot warmers--apparently not perfect solutions but might work for some bikers.

I previously related a recent episode where I stopped on a steel bridge in sub zero weather to take some sunrise photos and my feet froze (well, not literally). I rode for about 1/2 hour without them rewarming and they only got better when I stopped and walked my bike for about 5-10 minutes. I also think it was the fact that the foot stays pretty stationary on the pedals and that thicker socks only really work in a roomier shoe.

I used to ice climb a lot and it was pretty common to spend most of the belay kicking and wiggling my toes even in a thickly insulated boot.

I've never noticed my feet swelling during cold weather. If anything, it's the opposite. My feet tend to shrink slightly during cold weather and require tightening my shoes slightly. During the summer, my feet can swell enough to make the shoe painfully tight even with a relatively thin sock.

The reason that you get a roomier shoe for winter riding is so that you can put more insulation inside the shoe. Thicker socks and thicker insoles take up a lot of room. If you wear the same sized shoe as you do in the summer, you just don't have as much room.

There are a couple of things at work here. Yes, a steel bridge will suck some of the heat out of your feet but, assuming an open deck bridge, your feet are also surrounded by a lot of cold air. A solid deck bridge has more thermal mass and no air circulation so it won't get as cold.

Other issues are that we cyclists don't move our feet much while pedaling. You are correct that if you are any good at riding a bike, your feet are stationary and your ankle is moving and flexing but your feet are mostly locked in one place. That one of the reasons that our feet tend to hurt after hours of riding. We just aren't moving them and they can cramp and hurt. When you walk, you are flexing the foot from the toes to the ankle and the muscles are consuming energy and producing heat. My feet never get cold when I'm hiking or when I cross country ski because my feet are flexing all the time.

Same with our hands. If you are XC skiing properly, your hands are letting go of the pole and recapturing it. On a bicycle, you use your finger to brake but that's not something you are constantly doing.

And, yes, you should wear larger shoes for bicycling in the winter.

I've had a few weeks riding with toe clips. I like it. At first it was very awkward just getting started. Then I could ride but was still thinking I'd made a mistake. Now more and more my toe flips over the pedal and my foot slides in without a fuss.

Switching from clipless to caged pedals
 

I must have flipped the pedal hundreds of thousands of times without thinking about... Then once every other year or so, it takes three or four attempts and I'm wobbling all over the place... Go figure :/

I also wear soccer shoes for biking and lifting weights. And, of course, for playing indoor soccer. They are comfortable, simple, and are less clunky than running shoes.

Do they have stiff soles so as not to flex when you pedal?

Hmm they might not be as hard as some would like. It depends on the model. Some are fairly hard. But they work for me.

I also use clipless though.

I've gone from clipless to clips back and forth over the decades, from one bike to the next. Setting up toe-clips right now after being off bikes for 15 years or so. The main thing I like about both is being able to pull up on the pedals and use different sets of muscles. I hope I'm not the only one that does that:) That's where those half clips would be useless I think...

I have a few hundred miles on these and can attest to their utility, comfort, and simplicity. They hold as well (almost) as my clip less, but are so simple to get out of. I can also wear regular shoes (no more grinding on concrete when I walk, garnering too much attention in places where I'd rather blend in). I feel more secure standing and pedaling too, as the Lambdas have a super wide plate form.

I'm SOLD!

I used toe clips for years before clipless pedals were invented. I prefer clipless (with SPD), but on my foldup bike I use toe clips.

On some of my bikes I use pedals that are SPD on one side, platform on the other. I do not consciously lift with my feet, but I have noticed if I wear regular shoes on the bike, I am so used to lifting my feet that my shoes do not stay on the pedals exactly where I want them.

Half-clips AFAIK intended just to keep foot from sliding too far forward. & maintaining proper foot position is one of the nice features of clipless. One can get good position also with clips or platform but more dependent on having the right shoe.