Long-wind caution: this is entirely too long of a story for what it is. Apologies.
This is my second winter of cycling and my first using clipless pedals. I'm using speedplay frogs, which I have been more than happy with since I got them last spring. So far, just riding to work, I have had no trouble at all with clipless in the winter. I would not even consider switching back to platforms. In the one 'close call' I've had so far, I unclipped without concious thought and was ready to plant my foot in case I slid out any worse. Thankfully this was not the case as I straightened things out, clipped back in and went about my commute.
One thing I have done in the snow after walking out of my workplace to the bike rack is to tap my feet against the crank arms before clipping in to expell any snow caught in the cleats.
Well, today I started taking classes for winter quarter and had an interesting experience. Upon exiting my last class, I did the tapping routine, yet could not come close to engaging my cleats into the pedals. After banging my feet against the bike several times and trying to clip in to no avail, I looked at the cleats. There were quite large mounds of ice covering them!
What I didn't realize at the time was that as I walked into a campus building, the snow of course melted off my shoes, but after leaving, the remaining moisture turned to a layer of ice. Though my longest walk was maybe 250m, this was enough to cause significant ice build-up.
To resolve the issue, I walked my bike up to the door of the nearest building, went inside and knocked the ice off the cleat with the back side of my pocket knife blade. After that it was smooth sailing.
Just a note to those new to winter clipless use - watch out for ice build-up if you're walking around for any kind of distance!
