Freeze Thaw

Last year was my first-ever experience with mountain biking in the winter. Back in the ’90s, I was a casual, weekend-only, warm-weather mountain biker. Nowadays, in Patapsco Valley State Park, it’s all about avoiding the crowds. That means riding on weekdays, usually in the morning, and often in the cold.

One of the first things I learned about mountain biking in the winter is that I stay warmer on the trails than I do on roads. My first few times out, I dressed essentially the same way I do for cold road rides, and found myself getting hot and sweaty. I’m not sure why this is, but it probably has something to do with the slower speeds involved, as well as the tree canopy and terrain, all of which combine to reduce wind chill. Mountain biking is also more like interval training than road biking. There are short stretches of heavy exertion, alternated with downhill bursts, and occasional dismounting to get around obstacles. On top of that, you have to move around on the bike a lot more to keep a stable center of gravity through technical sections. All in all, it’s a much more dynamic activity than road biking, and involves a lot more muscle groups (particularly the core muscles). The upshot of all this is that I’ve learned to dress somewhat lighter than I do when I hit the roads. Of course, the only problem there is that whenever I do hit a short stretch of pavement, I get cold really fast. I try to minimize riding on pavement when on the mountain bike, but a certain amount of it is unavoidable.

The other thing I learned about is the strange phenomenon known as the “freeze thaw cycle” that affects the trails during the colder months. Overnight and in the morning, the trails are frozen, which makes for fantastic riding conditions. However, once the sun warms the ground above freezing, all of the moisture thaws out, and the trails turn into a muddy mess. This was a constant problem when I was commuting by MTB. The morning commutes would be total frozen awesomeness, but my afternoon rides would be mud baths. There were a lot of days where I rode home on roads, in the interest of staying off the trails. Of course, with my current work-from-home situation, this is not really a problem — I just stick to riding in the mornings.

We’re just now starting to get into the freeze-thaw cycle for the winter of 2020-2021. This morning, with the temperatures hovering right around freezing, the exposed trails were frozen, but the trails deeper in the woods were still thawed and a bit soupy in places. Trail conditions have been less than ideal lately because of our extremely wet fall weather, so I’m counting the days ’til the overnight temperatures fall down to the low-to-mid 20s, which will freeze everything up really nicely for my morning rides.