Here’s What Happens to Your Suspension When It’s Freezing Out
Updated: Apr 7, 2020
Some cyclists can spend all winter inside chasing their virtual buddies up imaginary mountains on the internet. Other cyclists will ride no matter how frigid the weather.
If you’re in the latter camp, you might have noticed a decrease in suspension performance. This isn’t just your perception, or the misery caused by the cold. When it’s cold enough for your water bottles to freeze, and your non-cycling friends to ask: “Are you sure it’s really a good idea to go out in this weather?” your shocks feel it too and they act a whole lot different than they do on a balmy summer’s day.
Yes, by the way, it is a good idea to go out. Bike riding is way more fun than couch surfing, even when the couch is warm and the air is freezing. Second, yeah you should make some adjustments to your bike. I spoke to Josh Coaplen, an engineer at Fox, about what happens to suspension in the cold and how you can maintain the best performance.
Coaplen explained: “Fluids used in bicycle suspension components increase in viscosity as temperature decreases (and vice versa). This includes damper oils, bath oils, and greases. In general, as viscosity increases, actuation forces go up so your suspension will feel less plush and move more slowly for a given input.” Translation—when it gets really cold, your squishy bits require more energy to move. We’re not talking Arctic temperatures either. This change can begin when temps are as high as 50 degrees Fahrenheit.
Gases are also impacted by changes in temperature. In really cold temperatures, seals can get funky. The most likely issue here is something rubber or plastic freezing to a sliding part (the male part of a fork or dropper post) and being forced through a dynamic seal. “I have seen plenty of bikes taken off of bike racks with frozen chunky stuff on sliding parts and the rider using the wiper seal to scrape the stuff off,” Coaplen says. “That isn’t going to help anything.”
Understanding how air shocks are impacted by cold is fairly easy once you grasp the ideal gas law. This law is often expressed in the equation form PV=NRT where P and V are pressure and volume, and T is temperature, N is the number of moles of a gas, and R is the ideal gas constant. Don’t worry, you don’t need to work out the number of moles your shock contains, but knowing this equation helps us understand that as temperature drops, air pressure in the shock also drops, while the volume of air remains the same.
Often riders will claim that just riding a bike in cold temps will warm things up, but Coaplen says this is a fairly haphazard approach and depends a lot on the terrain. “If you are riding fast on a relatively smooth surface, you will probably never warm stuff up. The convective heat transfer will move the small amount of any heat built up to the environment too quickly. If you are riding slower but going through travel, things will warm up more quickly since the convective loss to the atmosphere is slower and the heat generation higher. Also, driving to a trail on a cold day with a bike on a rack will cool [suspension] down really quickly.”
Luckily there are a few easy solutions. First, riders should set their tire pressure and their sag for their intended riding temperature, not that of their heated house. If you dial in your sag in a 75-degree garage and ride in below-freezing weather, there is going to be less pressure in your shock and therefore more sag. Coaplan suggests riders set their rebound and compression to slightly ‘faster’ settings when cold. Remember the increase in fluid viscosity when it gets cold we talked about earlier? Bumping up the rebound and compression compensates for that. Coaplan also says running a fender and cleaning sliding parts will protect seals and wipers. There are more involved solutions too, like swapping out damper fluids, but that gets pretty technical pretty fast and if you’re already doing that, you probably don’t need advice on tweaking your rig for the cold.
It is worth noting that no matter what you shouldn’t expect the same performance in below-freezing temperatures as you would in 60 degrees. Remember that your tires, grips, and even shoes contain compounds that just will not work as well when it gets cold. That doesn’t mean you can’t ride, just that you might not want to go hucking the biggest gaps in town when the mercury plunges.
Of course, if it’s really cold, there’s always ski biking. But I really enjoy brakes.
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