While contemplating my idea of what the ultimate winter commuting bicycle would look like, I had to decide what brakes would be the best for the conditions I ride in. I chose rim brakes.
Rim Brakes? I knew when I put out pictures of my new Surly Belt Check winter commuter I would be asked, or criticized, about why I chose rim brakes over disc brakes for a bicycle designed for the sloppiest of winter conditions.
Again, I was building this bicycle for my specific winter conditions and what I felt worked the best. It is also part personal preference.
What conditions are specific to my winter commute? I mainly contend with steep hills. Duluth is built on a hillside overlooking Lake Superior. Through the course of one winter I can have just about every imaginable winter condition you could come up with. Snow of course. Freezing rain. Wet, sloppy roads from snow melt. Slush. Dry roads with intermittent icy spots from freeze/thaw cycles. Lots and lots of sand and salt. Packed snow or frozen rutted ice. Fresh powder. Fresh "greasy" snow when temps are around freezing. On and on. Winter conditions can last six months out of the year here. Early November until mid-April.
In a lot of these conditions, I'm going quite slow, 5-10 mph. Having lots of stopping power is not an issue. The most challenging terrain and the stopping conditions I'm most concerned about is when I'm going down a steep hill. Almost always there is a stop sign or stop light at the bottom. This is when I need to know I can stop my forward movement without worry.
A lot of it is common sense. Just like when in a car. Drive according to your conditions. If you want to be safe, you don't go screaming down steep hills covered in ice or snow and expect to be able to stop on a dime.
A disc brake in the slipperiest conditions is simply overkill. Dave Moulton recently did a post about disc brakes and road bikes . On slippery snow or ice covered roads while going downhill you can't even use your front brake. Or if you do, it's only a quick touch now and then. You essentially lose 60% or 70% of your stopping power because you can't use that front brake. The front brake will lock up on ice or snow. In those conditions it doesn't matter if it's a rim brake or a disc brake. It's going to lock up and cause a lose of control. I've been known to use the Fred Flintstone method of stopping when the back brake isn't up to the task and I can't use the front brake. I simply put one, or both feet, on the ground while braking the back wheel.
If you where to look at snowbike racing like the Iditarod Trail Invitational or the Arrowhead 135 , you'll notice that many of the bicyclists don't even have a front brake on their bikes. When riding on 100% ice and snow and averaging a blistering pace of 8-10 mph, a front brake is completely unnecessary. You never use it. It becomes extra weight that you never use, so why carry it on the bike. When I attempted the AH135 in 2007 and 2008 I had front and rear brakes. I always said, if I were to do anything like that again the front brake would come off. I never used it. If I could, I'd use a rim brake on my Pugsley since 90% of the riding I do on it is on snow. However, it's dificult to set-up a canti brake on a bike that has 4" wide tires.
One issue I did find with cantilever rim brakes is the salty water works it's way into every thing. It causes the brake arms to get sticky and the arms wouldn't release after you use them. I spent lots of time pulling off the brakes and lubing them. I solved this problem last year by switching to Paul Components Touring Canti's . It has a sealed stainless steel pivot that slides on over the canti studs on your frame. The brake arms then pivots on these. They go the whole winter without ever sticking and without any additional lubing.
Stopping power? Like I've already tried to say, you don't need gobs of stopping power when on slippery surfaces. You end up locking up your wheel. This may not seem like a plus, but when the road is covered with sand and salt, it gets all over everything. A little bit of sand on your rims actually provides more friction and more stopping power. Sure it will eat away your rim sidewall, but not as fast as you think. If I clean my rims on a regular basis during the winter, I can easily get three or four winters out of them before the rim gives way.
Don't you go through a lot of brake pads? No. I use Kool Stop salmon colored pads . They have a harder compound then other pads. I replace pads once a year. A single set of pads lasts me all winter, and then some. Occasionally I take a file to the pads to remove any embedded debris. This greatly increases the life of my rims.
Again, this advice is directly influenced by my own experience here in Northeastern Minnesota. Conditions where I would want disc brakes for commuting would be in rainy parts of the country. Rim brakes are no match for discs in rain. We really don't get a lot of rain overall here.