For winter commuting, am I better off buying or building a bike with MTB running gear or Road Bike? I ask because one of my commuting buddies complained that his Derailleurs got gunked up (highly technical term here) during several winter rides and he had to stop in crappy weather and clean them so he could continue his ride. I rode last winter on a mtb and never had the problem, though I did get a lot messier even with fenders.

Am looking to go to a little quicker bike so going from big fats to 28mm and was wondering how to select the rigging? Deore XT or Shimano 105s?

My vote is for MTB as you can have better gearing and really fat tires (the key to fun winter riding), and IMHO flat handlebar makes the bike more nimble. I also happen to really like mountain bikes so my opinion may be biased This was my first Winter riding no-matter-what and I had no problems with derailleurs. The trick is to use light oil not grease so it doesn't get sticky and brush it off after messy ride. You just have to re-apply the oil more often, but you have a clean chain. But this applies to both MTB and roadie drivetrains.

Also, I've been told several times that MTB parts are generally tougher than roadie parts.

I have never had a dérailleur seize, freeze, or otherwise become gunked up on me. Not riding through a foot of snow, not in -20F temps. Like the poster before me, sounds like poor choice in lubricants.

Road or mountain, neither one is going to be more prone to shifting problems. Fenders are a difficult fit on roadies, but then you can go with a cyclocross or touring frame which are designed with more clearance for bigger tires. Whether or not you want drop bars in snow is the question.

Derailleur gunking in winter is entirely a function of the the type of snow that day and how much you shift. Shifting often, clears the gunk most of the time. Cranking along in the same gear lets the gunk build up on the other 7 to 9. It has nothing to do with whether Shimano's marketing department calls it a road or MTB piece.

I'm a steady cadence cyclist. To keep my cadence steady, I run close-ratio cassettes and shift frequently. I seldom have gunking issues. I've run MTB stuff (but with road cassettes) and road stuff. I've never been able to tell the difference when it comes to gunking. I've run 105 for the past three winters and gunked once.

I ride with others who treat their geared bike like a single-speed and hardly ever shift. Their cassette becomes so gunked that then they can't shift.

And again, it only ever happens when conditions are just so--fresh, wet snow at around 29° or so as I recall.

Short form, don't worry about it.

The typical problem I have occurs when the weather turns really cold after a warmish day. Moisture can freeze in cable housings and elsewhere causing shifting problems. It hasn't affected my road or MTB components any differently. The other problem I have tends to more of a cumulative thing that manifests itself in the spring. A lot of sand gets dumped on the roads. Even with full fenders and a big mudflap, grit works it's way into the pivot points. Soggy, slushy weather seems to aggravate this. Over time this can affect shifting.

Corrosion on jockey wheel bushings has caused issues for me too so I'm going to try a set with sealed bearings next winter.

The one winter that was problem free for me in terms of shifting was when I was primarily using a road bike but I think that had more to do with the weather than anything else.

You would think that MTB components would be designed to be more tolerant of dirt, dust, and sand and might work better in the winter but so far I haven't really seen evidence of that. So I would mostly choose what works best for you in terms of gearing. For me that's generally meant MTB stuff. Studded tires and riding through snow can be a lot of work and I find lower gearing to be helpful.

Sounds like I should hang on to my MTB for the winter rides and maybe build a quicker commuter for the nicer weather. It is taking me about an hour to ride the same distance I was riding in about 40mins on my roadbike last summer. Now to just decide whether to try to build my first bike or to just buy one. Thanks everyone.

There are some good reasons to use a mountain bike on a winter commute.

Avoiding gear gunking is not one of them.

I bought an old MTB bike for the winter commuting. That was more to do with tire clearance and fender clearance than anything else. I threw on some drop bars and stem shifters and am now totally loving it as a winter commuter.

c_h: Whichever way you go, suggest you make sure you have room to mount studded tires. I did this past winter a little north of you (Herndon) with a cross-style bike & 700x35 studded tires. Missed a couple of days with the major business closures and I think I drove a few times, otherwise rode thru it. There were 1 or 2 days after the big snows where I would have liked an MTB with really low pressure tires. That might have made dealing with the slush piles on the roads a bit easier. The 700x35s were fantastic on icy and packed snow areas, but sketchy on soft stuff (front wheel tended to get knocked askew). I had a 2nd set of wheels with 700x32s mounted when I didn't need studs or got tired of listening to the tire knobs on pavement. One more thing - fenders rule!

If you think we will have another winter like 2009-10, I'd probably go with an MTB just to get better riding in snow. If a more typical winter, I think a cross or touring style bike that can take wider/studded tires is fine.