I've ridden the last 3 days, temps from 20's to low 30's.
Kind of takes the pressure off of keeping a pace.
Varying my attire to avoid excess laundry, but something always gets sweaty.

Under 40 degrees, I only go an hour. Over 40, business as usual, try to dress smart.

Today, I looked a lot like an alien. With a runny nose.

It's supposed to snow tonight but be in the 40's tomorrow, so I'll go again.

Just like running, the first 10-15 minutes are a PITA, then you're fine for 30-35 minutes, then you'd better head for home, because you're wet and it's only going to get worse.

I'm liking Pearl Izumi's shoe covers, some great arctic gloves I have, and keeping my ears warm. I think I may get a larger helmet for layering that stuff. I get everything, and I mean everything, on sale or through a co-op on CL that sells new donated gear to raise operating capital. I'm about to meet a guy who is giving up winter cycling, so I should be expanding my scheduled stuff, maybe even dropping the allowable temps to the teens.

I also wear a Giro Air Attack Shield helmet. My opinion is this helps a ton.

Plan A, low 30's:
Fleece-lined bib knickers by Capo, full Pearl Izumi shoe covers.
Under Armour base layer, , long-sleeve (heavy) fleece-lined jersey.
Head cover (incl ears) and helmet, Brooks knit gloves in New Balance mitten shells.
Pro: Ease of movement, still feel like a cyclist.
Con: You sweat in those bibs if you even slow down, then you get cold.

Plan B, upper 30's:
Fleece-lined bibs by Hincapie, almost too warm, the shoe covers.
Riddell base layer, Chicago Marathon long-sleeved running top, Livestrong anorak.
Headband with ear flaps, Headsweat over that, helmet.
Giro winter riding gloves.
Pro: quick to put on, and warm.
Con: Gloves are too cold, anorak flaps in the wind, no pockets.

Plan C, mid-upper 20's:
Performance riding underwear, In-Sport running tights, Hincapie wind pants, shoe covers.
Riddell base layer, Bellwether long-sleeve jersey, Pearl Izumi wind vest, then a windbreaker jacket.
Headband with ear flaps under full-head cover.
Arctic gloves not designed for riding.
Pro: You will not get cold, anywhere.
Con: I rode 55 minutes and the tights and base layer were soaked. that's bad news if I'd gone too far.
My hands sweated on the cuff area.

Plan D, low 20's:
Any pair of bibs, lined Asics running/wind/rain pants, shoe covers.
Descente long-sleeve base layer, loose Livestrong cotton long-sleeve base layer.
A fleece-lined long-sleeve jersey that's loose, and XL wind vest.
LG fleece cap with ear flaps and visor. Head cover w/open face.
Arctic gloves.
Haven't tested it yet.

Most of my rides, if my chest, fingers, ears and feet are fine, I'm fine.
I generally don't worry if my arms or legs are cold, if my core and extremities are warm.
Bare legs never bothered me, but they get wind-chapped and itch/burn.

I plan to add a couple more of the open-face head covers, plus the larger helmet to fit over it all.
I've got toe covers but once I rode in whole shoe covers, that was the end of them.

What I don't like about winter riding:
1-By the time you get dressed, you're sweating. Solution: get dressed in the garage.
2-Not real crisp shifter feel. Solution: don't hurry, anticipate hills.
3-Doing laundry. Solution: ride clean, let things dry between rides, go twice per laundering anything that didn't get wet.
4-Can't really do long mileage because of the sweat factor and having to change clothes to stay dry.

What I like about winter riding:
1-Chances of meeting other riders and wasting time talking is slim.
2-Chances of stopping at convenience stores for water is slim. I never carry water in the winter.
3-No pace pressure. I just finish the route, get my miles/time in.
4-No one else wants to ride, so it's on my schedule.