The good news here is that it's entirely possible to cycle through the winter in Ithaca in reasonable comfort. However, it does require some significant investment in clothing and gear, and it takes longer to transition from inside to outside.
The climate in Ithaca in particular is thus:
So it's cold, colder than New York City or Boston. But not cold like Minnesota or Alaska. My particular daily routine at the moment involves riding down the hill from my rental house at about 850' elevation to a cafe downtown at about 400' elevation at 6:30am, when the temperature is usually at or near the overnight low. I think the coldest night we've seen so far was 7oF. Also, there is sometimes a headwind with gusts of up to about 25mph, and thus about 50mph after adding the speed of the bike down the hill.
In addition to daily commuting and errand running around town, I also ride 3-4 hours on a Sunday for exercise. So far, all my riding here has been done on my touring bike - a Rivendell Sam Holstein with fenders, rack, and baskets. (So you can tell already that I'm about comfort and convenience when cycling, not about speed or fashion).
The bulk of the time, I am riding on dry salted roads. Maybe 1/4 of the time, I am encountering either moderate amounts of slush, or icy patches. I also regularly ride on a gravel trail when there is up to 1 or 2" of snow on it. I have not tried riding single-track or on ice lakes, (yet anyway - I might when I get around to getting some studded tires for my mountain bike). I haven't yet encountered deep snow on the roads.
The adaptations I've had to make are as follows:
- Following the pointer of reader kjmclark, Peter White Cycles is a fantastic resource, both as a supplier of useful products but also as a great repository of wisdom and insight. It's worth studying the entire studded tire page at length. I bought from them a set of Schwalbe Marathon Winter studded tires (35x700). These seem to be a fantastic product - they knock maybe 2mph off my speed on dry road, but I have been able to cope with perfectly fine traction on ice and up to several inches of fresh snow. Pay attention to the warning at the link above to avoid heroics, but I have found I can get up the steepest hills around here without traction loss. I have yet to lose a stud. Without studded tires, you simply cannot ride on ice or any significant amount of snow, so the alternative would be to leave the bike at home a certain fraction of the time.
- I wear several layers of fleece/wool under a heavy skiing type coat - the exact amount of layering depending on the conditions of the day. I also use long fleece underwear under my regular pants. So far I haven't needed ski pants to be comfortable.
- I installed reversible pedals (Shimano M-324) on my bike. On the colder/snowier days, I use the flat side with Arctic Sport Muck Boots with wool hiking socks. No points for style, but I've yet to encounter a morning that made my feet cold in these.
- On the coldest mornings, I also use two layers of gloves - thin wool gloves under heavy goretex/thinsulate mittens. The mittens alone were not enough to prevent cold hands on the downhills, and the thin gloves are a help because I can do stuff like locking up the bike and turning lights on and off without removing them. Pay attention to the details of the interface between mittens and coat - you want one to go clearly over/under the other so there isn't much scope for cold winds to get in between. Typically this means a coat with straps/velcro at the wrist that can be tightened to get under the flange of the mittens.
- Also, my experience is that you can't ride when it's actually snowing without eye protection - the snowflakes land in your eyes and hurt, and it keeps happening every few seconds. Regular cycling goggles fog up. So I'm using a cheap pair of ski goggles with clear lenses that have anti-fogging compound. They work great, except that the side visibility is poor and so there are certain situations where I have to actually stop on the shoulder and look back before turning left because I cannot see over my shoulder well enough to make the maneuver safely otherwise.
- Going down the hill in the morning on the coldest mornings is seriously unpleasant without face protection. I initially used a fleece balaclava, which was ok into the late fall, but became inadequate after that. My latest discovery is the Cold Avenger balaclava. This thing is expensive and fits imperfectly, but does solve the problem better than regular balaclavas. It has a more windproof kind of fleece, and a ventilator that does a certain amount of heat exchange between the inbound and outbound air. My experience is that both my face and my lungs are now quite comfortable as long as I'm careful to adjust all the moving parts properly - hood, face mask, goggles, and bike helmet. Plus I look like Darth Vader when I stride into the cafe in the morning!
Although there is a certain amount of hassle involved in figuring out what to wear on any particular day, and getting suited up, to me it's still totally worth it. The thought of exercising by sitting inside spinning away on a trainer going nowhere just seems completely tedious versus being outside in nature watching the changes in the seasons and the landscape. The other thing I've found is that the amount of amazement and kudos I get from bystanders for riding in the middle of winter here is quite gratifying, and out of all proportion to the actual discomfort I experience when properly attired.