Trail ruts caused by riding partially thawed trails.
What's the big deal with freeze thaw cycles?
Dirt trails are extremely venerable to rut damage during the transition to and from winter because colder temps prevent the soil from drying. When soil freezes the growth of ice crystals push soil particles apart leaving large gaps that can fill with water when the ice melts. In a thawed state this dirt is much like a sponge and will absorb large amounts of water. It is also hyper sensitive to disturbance by foot/bike traffic and flowing water and will form ruts with little effort. Direct sunlight and above freezing daytime temperatures can thaw the top layer of frozen dirt and create an easily rutted, greasy, muddy mess on the surface. Overnight, lower temperatures refreeze the top surface of the trails, ruts included, and the process repeats when conditions allow (hence the name freeze thaw cycle).
Why are ruts bad for trails?
Expanding ice crystals loosen the compacted trail surface creating cavities that trap water. Result: a very thick mud when thawed.
When ruts develop along a trail they channel water, causing erosion of the trail surface, and slow the drying process. Rain is highly erosive to trails when the ground is frozen and ruts greatly increase the chances of erosion by flowing water. When the soil is frozen, water can't soak in like normal and flows along the top surface in large quantities. Ruts on a trail can intercept these flows and divert them along the length of a trail. As the water flows down the trail and picks up speed it also picks up soil particles and washes them away. This can leave behind deep ruts tens or hundreds of feet long in extreme circumstances. Come spring time, ruts can also hold pools of water on the trail surface and prevent it from drying as quickly. If these puddles are disturbed by bike tires or foot traffic they can quickly turn into large mud pits. Fixing these areas eats up trail volunteer time that could be better spent on other projects. Wet areas like this also prolong trail closures.
Frozen footprints left in a trail after a midday thaw.
Do freeze thaw closure conditions ONLY apply to bikes?No. Both bikes and foot traffic have negative impacts on soft trails.
Is it ok to ride fat bikes in freeze/thaw conditions?
While fatbikes have lower ground pressures than regular bikes, they can still form ruts and degrade soft trails. We advise against riding ALL bikes on dirt trails when conditions are not suitable.
If there is snow on the ground is OK to ride/hike?
In most cases it is OK to use trails when they are snow covered but if the ground below is not frozen and there is only a thin covering of snow it may still cause ruts/footprints. Use your best judgement and hit the pavement if you're leaving marks in the trail.
Footprint ruts hold water causing the surrounding trail to stay wet and closed longer. They are also very time consuming to repair since a single user can create hundreds of impressions in a matter of minutes.
Tips for riding during the winter months
- Pay attention to the trail status on the FORC homepage as well as the signs posted at local parks.
- Don't use frozen trails when the temperature is above freezing.
- Use frozen trails early in the morning before they have a chance to warm.
- Don't ride if the temps are hovering around freezing and it is sunny. Wait until temps are below 28F and even then there may be thawed areas.
- If after following all the above guidelines and the trails are still too soft, turn around and come back another time. A single user can damage thousands of feet of trail under these conditions.
Other options to stay active during the winter
If the trails are too muddy to ride, there are alternatives to get your winter mountain biking fix.
- Urban rides and trips to Rays Indoor Mountain Bike Park are common during the winter months. Keep an eye on the Lets Ride and Road Trippin' forums for ride and day trip announcements.
- If there are a few inches of snow on the ground and the trails are frozen below, a fat bike can do wonders to relieve those winter riding withdraws.
- Exploring the shores of Credit Island via fatbike is also a great way to spend a day and because it's a floodplain and there are no maintained trails, freeze/thaw and mud aren't an issue.
- The many local bike paths are also an option for winter riding. They are not crowded during the colder months and cities usually plow them quickly after snowfall.