‘Tis the season. No, we’re not jumping on the Christmas-decorations-before-Thanksgiving bandwagon. We’re talking about an evil much deeper and harder to fight: freeze-thaw.
We’ve already seen our first snowflakes of the season, and while it’s exciting to whip out the fat tires and dig out your pogies from the “Winter Gear” bin, it’s worth refreshing your weather app and taking a look ahead. This cold snap is just the first taste of a month that promises to see temperatures tickle the high 40s and even low 50s, sometimes just a day or two removed from overnight lows. That has a big impact on more than just your sanity, because these big temperature changes can make your rides hard to plan and trail conditions hard to predict.
It’s the season of the freeze-thaw cycle, when trail that is frozen solid gradually melts as daily or weekly temperatures rise. Frozen ground leaves moisture in the soil, and even if it’s been a while since it has rained, that moisture puddles and pools as it melts. This can be really tough for trail associations to manage, with riders heading out in the mud and causing damage. Sometimes, it isn’t intentional; some people are honestly oblivious to the issues that make this time of year a challenge. That’s why we’re putting this together!
One important thing to remember about freeze-thaw cycles is that they don’t impact all trails equally. Different types of soil drain or retain moisture better, with sand being probably the most resistant to the issues we associate with freeze-thaw. Locally, trails like Merrell and Luton are more susceptible than sandier places like Yankee Springs. Even specific sections of trail that are lowering lying, are composed of different soils compositions, or see more shade and perhaps melt later in the day can make even three to ten-foot sections of trail drastically different from other areas. That’s a big reason why just “having a look” from the trailhead can get us in trouble; things might be fine for miles before you find yourself in a veritable swamp, but at that point, you’re committed to the ride.
There are two main ways freeze-thaw contributes to trail damage, and neither are terribly different from simply riding after a period of heavy rain. As the ground softens, it’s much more susceptible to ruts. Tires cut through the softer topsoil until they hit something hard. This might be another layer of firmer soil, like clay, but it can also be just another layer of icy soil. If that becomes exposes, it also gives under tire pressure, which means the one-inch rut becomes two inches, then three, until there is significant damage that sinks the trail bed lower and the singletrack becomes a permanent rut itself. This also tends to expose more roots, rocks, and other trail hazards that aren’t always safe or fun to ride.
The second source of damage comes from that totally human and relatable desire to avoid having to wash your bike. When riders come upon a mud puddle, they go around it. No harm done, right? Nope. Most often, skirting around puddles only causes that puddle to get bigger. That’s never more true than when the soft, moist ground surrounding the existing puddle is squashed by more tires. The effect is to not just expand the puddle but to add even more water to it. The next rain or the next cycles contributes even more moisture, creates an even wider footprint and sees a new perimeter for riders to go around.
Unfortunately, certain drainage and trail systems make puddles almost impossible to stop, but we do have the ability to recognize poor trail conditions and make smart decisions when we come upon mud. If you’re riding, always go straight through the mud puddle. This will still risk a deeper trail bed, but at least our singletrack won’t end up being five feet wide.
One or two puddles won’t close an entire trail network, so respect trail directors when a trail is closed. That means the trail as been inspected and deemed not only too muddy but also just not a fun place to ride. We rely on mountain bikers across the region to check-in and update others on trail conditions on TrailForks, but if you prefer to post and check on Facebook, that’s okay, too. The damage caused by riding in freeze-thaw conditions can take countless hours to fix, and that’s time our volunteers would rather spend making expansions and improvements, not cleaning up after irresponsible riders.