Freeze-thaw cycles have taken on a broader meaning for mountain bikers since the advent of fat bikes and groomed trails has extended the riding season. Today, riders need to be aware of how rising and falling temperatures impact snow and soil conditions, as well as how even minimal but high-impact riding can cause lasting problems.
If you’re newer to mountain biking and fat biking, or just need a refresher, find out how freeze-thaw cycles can negatively impact trails and force our volunteers to invest extra time to repair damage.
What Are Freeze-Thaw Cycles on Mountain Bike Trails?
As the name suggests, these cycles are the freezing and thawing of soil as temperatures rise throughout the day and fall overnight. Freeze-thaw cycles are very common in spring (think March-April) and late fall (November-December).
For groomed trails such as the Winter Sports Singletrack, Glacial Hills, and Cadillac Pathway, these cycles also affect snow conditions. Warm, above-freezing temperatures cause snow to melt, resulting in “mashed potato”, slushy snow, while below-freezing temperatures cause trails to harden up and, in many cases, freeze over.
The problems arise when riders cause deep ruts due to riding in soft, thawed conditions. During these times, riding and hiking in soft snow or mud leaves deep ruts or footprints.
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Dirt with ruts collects water, resulting in mud, which in turn makes the soil even softer and causes even more damage.
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Snow with ruts is very difficult to repair, especially without a solid base. This forces riders to ride in a single, narrow rut - and that’s not a lot of fun.
How To Prevent Damage from Freeze-Thaw Cycles
Understanding the temperature and moisture conditions that raise the risk of trail damage is the first step to preventing further problems.
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If temperatures are below freezing overnight and above freezing the next day, expect soft conditions; if trails are still wet from rain or snowmelt in the spring or fall, expect the soil to be relatively muddy.
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Check with NMMBA (or your local trail association) to see if the trails are safe to ride. Most trail associations post closures or recommendations to prevent damage during freeze-thaw cycles.
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If you show up to ride and leave a clear rut in the snow, maybe go ride a road or a two-track instead. Remember that running the correct tire pressure is a big part of protecting groomed winter trails (and having way, way more fun).
Support Trails in Northern Michigan
Trails don’t fix themselves. Damage from irresponsible riders during freeze-thaw cycles costs our volunteer groomers a lot of time and effort that would be better spent on trail expansion and improvement. Do your part by steering clear of soft, wet trails that may be at risk of damage, and support our work by becoming an NMMBA member today!