
Introduction
Fat biking in the snow is an incredible experience. The freedom to explore winter landscapes, the unique challenge of navigating soft surfaces, and the sheer joy of gliding over a pristine snowpack are all part of the allure. But maximizing your enjoyment, minimizing your misery (for example when you’re not prepared) and minimizing your impact on the trails hinges on one crucial factor: Tire pressure. "How low should I go with tire pressure?" is the most common question I get from my fat biking clients, so here's what I teach them.
The Goldilocks Dilemma
Finding the "just right" tire pressure is a bit of a Goldilocks problem:
Too high, and you'll be fighting the bike and snow every inch of the way. The tires will sink in, you’ll lose traction and come off the bike (often crashing off of it), you will expend significantly more energy, and your tires will dig into the snow, creating ruts that ruin the trail for others. Not fun.
Too low, and you'll be creating too much drag (more energy expended) and won’t enjoy the speed that you could at a higher pressure. Getting really low may lead to tire sidewall damage, pinch flats (with tubes), burbing (for tubeless) and even the tire coming off the rim. Also not fun.
The Sweet Spot
The goal is to find the sweet spot where your tires float on top of the snow with minimal drag while still providing enough support to prevent excessive drag. This will vary significantly depending on several factors:
Trail Conditions: Groomed trails (and the timing of the grooming), freshly fallen snow, packed powder, and deep snow all require different pressures.
Weather Conditions: Temperature, wind, sun/cloud conditions - these all play a factor.
Rider Skill: More experienced riders may be able to run higher pressures based on their skill in handling softer snow conditions.
Rider Weight: Heavier riders will need lower pressures.
Tire Width: Wider tires can run lower pressures. 4.0” width or bigger works best and the wider the better.
Front vs. Rear: As a general rule, you will want 0.5-1.0 PSI less pressure in the front tire (example: 3 PSI rear, 2 PSI front). This has very little impact while climbing and is safer while descending.
Tubes vs. Tubeless: A tubeless setup offers a significant advantage by allowing you to run much lower pressures. This is crucial for achieving optimal floatation and minimizing trail damage. Tubeless also saves about a pound of weight, which is very significant especially as rotating mass in the tires.
"Low" is Relative
If you're accustomed to riding 20-30 PSI on your summer trail bike, 5 psi on a fat bike might sound dangerously low. However, in most cases, it's not nearly low enough for optimal snow riding.
How to Measure Tire Pressure
Get yourself an analog tire gauge with small increments (¼ PSI or less). Here’s a non-affiliate link to my favorite.
The Science of Snow
Groomed trails require time to "set up" after grooming. The process of refreezing and firming allows for better snow riding conditions and minimizes the impact of fat bike traffic. Riding on freshly groomed trails can be a miserable experience for yourself, can damage the trails, and can negatively impact the experience for other users.
Snowshoe traffic also greatly speeds compacting of the snow resulting in improved snow riding conditions so be sure to hug a snowshoer today! Check trail condition reports early and often.
Finding Your Ideal Pressure
The best way to find your ideal tire pressure is through experimentation. Start out with a lot less pressure than what you think you need. In most cases, it will be too much as most people start out way too high. Let air out as needed while on your ride (each time you spin out or make a rut is the time to do it). Keep reducing tire pressure until you find the sweet spot based on all the factors discussed here. It’s a good idea to carry a small pump or a CO2 cartridge in case you let out too much air.
Key Takeaways
Tire pressure is crucial for a positive fat biking experience and minimizing trail damage.
Find the balance between floatation and support.
Consider factors like trail conditions, weather, rider skill, and weight.
Tubeless setups allow for lower pressures.
Respect groomed trails and allow them time to firm up after grooming.
When conditions cause you to sink in or create ruts even after tire pressure adjustments, chalk the ride up to an excellent learning experience, get off the trail, go home and come back another time.
Thanks for Riding with Me / Wrap Up
There are a lot of factors involved in selecting the correct tire pressure. Begin to master them (through experimentation and education) so you can unlock the full potential of fat bike joy! And ALWAYS turn around to go back to the trailhead if you are sinking in after adjusting tire pressure. Don’t turn what should be a joyful ride into a poor experience for yourself (by over working) or for others (by ruining the trails).
I hope this article has helped you learn about selecting the right tire pressure so you can enjoy your fat bike riding to the fullest!
Oh, and if you're looking for tips on riding in cold weather, check out this post (a quick 6 minute read).
**Bonus** Get Coached
A shameless plug? Maybe, but I believe that skills coaching is the fastest way to reach your full riding potential. Nothing beats having a qualified coach giving you real-time feedback regardless of your riding ability. If want to ride more safely, have more fun, go a little faster and/or just feel less fear on your bike, let me help you get there. Mountain biking doesn’t need to be extreme or dangerous: learn the fundamentals of safe, confident and fun riding.
Click Here to Book Your Next Lesson
Don't miss out! Get notified as soon as new mountain bike skills content is published. Sign up here.
About the author: Joel Zieve is a Certified PMBI Mountain Bike Skills Coach in the Ogden Utah (Northern Utah) area. He specializes in helping beginner, novice and intermediate riders ride more safely, have more fun, go a little faster and feel less fear on their bikes. He is also the host of the Podcast "Aging on Dirt". Click here for more information about his coaching programs.
Special Thanks: Thank you to Alan Wheelwright and John Pendelton for your contributions to this blog post!