Winter biking. Still a novelty to some, it's become a go-to activity for many of us. No more off-season. Once the snow finally accumulates every fat tire enthusiast is itching to get into the powdery goodness. After the snow flies, conditions are usually soft for a few days. If you’re used to riding the semi snow-covered or hard-packed trails, this may be a huge awakening for you. And then later in the season, it gets hard and icy.
Tire selection and pressure can make or break your ride in sketchy or soft conditions. Good pressure means the difference between walking every hill or dancing up the grade. Wide tires with deep, well-spaced treads are your friend on powder days. But you can make any tire work by making sure your pressure is low enough.
It’s hard not to leave a rut in deep snow, but if you can’t track in a straight line, or your back-end is breaking loose when you pedal, your pressure is likely too high. You need to let out some air.
Tips for adjusting your fat tire pressure
1. Increase your contact patch
The key to achieving good traction in snow or sand is tire flotation. If you start riding and you find yourself breaking through the snow layers, leaving deeps ruts, slipping around corners and driving off the trail, you probably need lower tire pressure. The graphic below shows how 40% less air in your tire gives you 10 to 30% more contact patch for different tires width and rim combinations. This adjustment means that your tire will squish more to provide float and put more of your tire lugs in contact with the snow to provide traction for climbing and cornering. When conditions are bullet proof, more pressure can help regular tires to push into the hard surface; try a little more pressure to stiffen up those lugs to bite more. With studded tires, you want to adjust pressure to get as many of those sharp metal spikes digging into the ice as possible; your regular low pressures will be a good starting point. Be aware that when you are riding with studs and you lean your bike, at some point the studs will no longer be biting into the surface and your wheel could slip out from under you.
As a starting point, for hard conditions, and freezing temperatures, 6 - 10 psi is a good target pressure depening on rider weight. When conditions are soft and the temps are above 0º, anywhere from 1 - 4 psi can work well.
2. Start out with more pressure than you need
Fatbike tires have lots of volume and are generally a pain to pump up on the trail. Especially when it’s cold. A low-pressure gauge that measures 0-30 psi is the best way to set tire pressure. It’s a good idea to start with 8psi for medium riders and 10psi for Clydesdales and adjust down on the trail. The chart below tells you how much tire pressure to set indoors so when you head outside you get the pressure you want.
To find the lowest safest pressure for almost any tire of 4” or 5”, sit on your seat with your full weight on the tire, if the sidewall starts to pucker or fold a little bit, that is your safest low pressure.
Central Wisconsin Offroad Cycling Coalition, Justin Kauffman Unsplash.