Hey all!
I started bike commuting on my Giant road bike with caliper brakes this summer. That wasn't too hard to get into. I already had most of the stuff I needed, so I bought a couple bright lights and got going. My commute is 5 miles one way, with lots of hills. I'm fortunate to have 4 miles of bike lane and the additional mile is fairly wide. When it started raining I put rain gear on and kept going. I fell once making a turn over a slippery wet manhole cover. That didn't phase me too much. It wasn't a bad fall, I understood the cause and effect and how to prevent it from happening again. Now, though, I'm struggling a bit. The temperature has been fluctuating around freezing and one day I fell going down a hill that turned out to be icy. I was surprised because it hadn't rained recently. This fall has kind of gotten into my head. I started worrying about falling in traffic, or just having a bad fall that resulted in serious injury. I purchased Marathon Winter tires for my bike, and of course the weather got warmer right after I put them on. For the past week I've been riding on basically dry roads on these studded tires. Today I went out and realized that I had left my road bike's headlight charging at work (I got a ride home with a coworker yesterday) so I decided to ride my mountain bike to work instead of trying to swap headlights (my mountain bike headlight is an older style that is annoyingly difficult to get on and off, especially when you are worried about being late to work). The ride in was decent. My Novarra mountain bike has disc brakes and fat knobby tires. I felt a lot more comfortable than on my road bike. My commute is short and it wasn't much slower on knobby tires than on the studded tires. Is the stability I felt on the mountain bike today just a figment of my imagination? I've never fallen on the street on my mountain bike, so maybe my hind brain is convinced that it isn't as scary as the road bike.

So, what would you do in my situation? How would you set up a road bike and/or a mountain bike for winter commuting in the Pacific Northwest? What criteria would you use to determine which bike is better for a given day's commute? Should I return my Marathon winter road tires to Amazon and just keep the road bike for days that are well above freezing?

I'm not super familiar with all of the terminology, but if you have questions about my current setup, I'll do my best to answer them. Thanks in advance for any help!

Hokay... you've managed to put out a lot of information, and not enough information at the same time. Where in the PNW? It matters, I think. You have an advantage in that you have two bikes. I've managed 10 winters in the PNW without a set of studded tires. Last year I thought about it. I'm riding right in the city. NE Portland mainly. Highway overpasses freeze if the overnight temps drop below 32*F. Most everything else will be safe on regular tires. The hill you fell on may have had moisture condense overnight even without rain falling. If you are say in Seattle or someplace like that you may well be advised to have that mountain bike ready to roll with the studded tires and only use the road bike for 'heat waves'. Road vs. Mountain as to handling should not be an issue. Mountain is, of course, 'better' for the purpose of carving through rush hour traffic because you are relatively upright and we are wired to orient ourselves in space bolt upright. Nevertheless I do 1/2 my commuting on a pretty aggressive road racer type bike with clip on fenders and clipless pedals and 700C, 25mm clinchers. The riding position on the race bike is radically different from the riding position on the city bike with the 26"x 2.0 comfort tires. Either will get the job done. I haven't fallen yet on the roadie but that may be because overall I ride it less and have had it for a shorter time than any of my other bikes. When I have fallen, it has always been because of some road surface issue. I try very hard not to hit, or get hit, by other road users, especially motor vehicles. Good luck. Post back with more info about your route and you may get more detail from others.

I'm down in the southern Willamette Valley. Pretty odd weather lately with a lot of frigid temperatures and not much rain.

I don't use studded tires because I can usually work my riding schedule around ice and snow. If I was riding studded tires for short rides, they'd probably go on a MTB. On the other hand, my average RT commute is somewhere between 25 and 50 miles, and I just like riding more road oriented bikes. Drop bar MTB?

Commute on what you are comfortable with, be it road/gravel/cross/hybrid, or MTB.

Sorry for the word vomit on the first post, but I'm not sure what is relevant and what isn't! :-) I'm in Western Washington, specifically Tacoma. We rarely get snow, but temperatures have been dropping overnight into the high 20s/low 30s. I've ridden my MTB and my road bike for roughly the same amount of time in my life, and before my second fall on my road bike, I would have said I was equally comfortable on both of them. Honestly, the reason I got the studded tires for my road bike was because I just didn't think about my MTB. I associate my MTB with recreational riding during the lazy days of summer, not a business like, make-it-to-work on time commute.
I want to be more mindful about continuing my commute through the winter. I know 2 people who have broken ribs because of black ice in this area. I also want to spend my limited funds on the right equipment for my situation. I jumped into studded tires, but now I'm wondering if just switching to the MTB for days that are freezing would be better.

My commute:
5 miles
Hilly
Temperature often fluctuates around freezing
Frequent precipitation
I have to leave early in the morning. I can't wait for it to get lighter and warmer. My job doesn't have that kind of flexibility.
Traffic is not much of an issue. It's not like Seattle. I don't have to maneuver through multiple lanes of traffic to make a left hand turn or anything like that.

My bikes:
Giant OCR1 Road bike
Marathon winter tires (700x35) could switch back to Gatorskins (700x25)
Rim brakes



Novarra Bonita Mountain Bike
Stock tires (26x49/52)
Disc brakes

Thanks for any feedback. Even typing out my situation has helped me think about it a little more clearly.

I didn't realize you got the studded tires for your roadie. That being the case, that is the one I would ride through the winter, if an early morning commute and overnight temps below freezing are the norm. Just because you haven't fallen on your MTB doesn't mean you couldn't. All bets are off on ice. Knobbies are just as vulnerable as anything else on ice.

I'm thinking about returning my studded road bike tires to Amazon or selling them on offer up and getting studded MTB tires. I really liked the feel of the disc brakes and the more upright stance on possibly icy days. Then I can just keep my road bike setup for the days where ice isn't a possibility. I'm going to my LBS today to see what they have in stock for studded MTB tires.

So you bought tires, used them, and now want to return them? I could see a return if you didn’t use them or they are defective, but they are yours now. Unless of course the seller offered a free trial period with no questions asked return policy.

It's Amazon. They take returns on stuff for any reason. It's part of their business model. I'll have to pay return shipping, but they will put them back up for sale in the warehouse as used. If bike tires don't have the same policy as everything else on Amazon, then I'll sell them on Craigslist something similar.

If your tires are super knobby I would say yes that's an illusion, the contact patch of knobs is no larger and certainly less reliable than road slicks. Now, fat slicks, those are awesome! 2" fat slicks run at lower pressure so they deform to stick to every declivity in the pavement, you never lose contact (except in the case of black ice as you have been discovering...)

I have settled on a cross bike w/ 35mm marathon winters for black ice season for my ownself but I think a mtn bike w/ 2.0 slicks and 2.0ish studs would be perfect for all commuting conditions around here. Black ice season is worst right now (in PNW), until Feb maybe, especially when it is in the high 30s and clammy; the high 30s is measured at chest/head height, the asphalt is 32F and you can pretty much count on it being frozen. Check this out: Cliff Mass Weather and Climate Blog: Black Ice

I don't find *knobby* tires of any use on roads and they drastically hurt traction on thermoplastic road markers and metal stuff. Conversely, the light tread of marathon winters and marathon extremes (my regular tires for that cross commuter; marathon winters minus the studs) is great for digging into the leaf paste layering my fall/spring commute. Marathon winters are not great for heaps of snow but we don't get that here, I think they are perfect for the black ice we get.

I have a road bike (2 actually) but I just don't ride them at all during headlight season.

Thanks for your input Hardy! I'm going to buy some Marathon Winters for my MTB and save the road bike for spring, summer, and early fall.

Welcome to winter commuting! SheldonBrown.com has some great articles on winter commuting.

My guess is your MTB has a lower standover height; this is good in case you have to bail unexpectedly. Also, you'll like the disc brakes because they still stop you when they get wet. I echo everyone else's responses regarding knobbies, don't use them for commuting. Studs may or may not help, you can try them for yourself and see what you prefer.

I would add that your winter commuting kit should be well stocked so you don't freeze to death in the event of a tire blowout/etc.

Sheldon also warns against using any sort of pedal retention in the winter because it decreases your flexibility in footwear and also can be dangerous.

A lot of folks prefer IGH/SS/Fixies in the winter because they are not as susceptible to snow/ice buildup in the rear cassette/derailleur, IMO, I would not make major changes to your nice MTB unless this becomes a real issue.

I live in Spokane but lived in Bothell for 1 year