With a simple adjustment, you have an incredible amount of control over how your bicycle will handle on your next ride. Simply adjusting the amount of air pressure in your tires has a very direct and immediate response on the way your bicycle feels and responds to the terrain where you ride. Many mountain bikers have known this for a long time, but it is completely valid for road and path riders as well. We’ll start with mountain bikes for this installment, and talk road, & path bikes on the next.
When we talk mountain bikes, most tires range in pressure from 30-65 psi. Your pressures will differ depending on the type of terrain that you’re riding. For technical mountain biking, where you’re travelling over exposed rock, roots, logs, etc, the key is to inflate the tire just enough so that it will deform over the rough parts of the trail. A correctly inflated mtb tire will also dig in to loose dirt to give you more confident cornering, & climbing on steep terrain. If you go too low, you run the risk of developing a pinch flat, where striking a tire hard enough on exposed terrain will cause the tube to split as it gets pinched between the sidewalls of the rim & the tire. You’ll also suffer from the tire folding over too much during cornering, giving the bike an unstable-“wallowing” sort of feeling, especially at high speeds.
The most common error we see is mountain bikers with over-inflated tires riding on technical terrain. When you fill your tire to it’s max pressure, it rolls fast, but is unable to deform when you hit rocks, roots and other trail obstacles. What results is not only a rough ride, but it feels like you’re bouncing off everything in your path. You work harder than you need in order to control the bike, and suffer from fatigue sooner as your body has to absorb all the impact, rather than the tires. On full-suspension bikes, it can also cause your suspension to work overtime, not as it is intended.
Your riding weight (your weight + helmet, hydration-pack, etc) and terrain will alter the amount of air pressure required for an optimal ride. We suggest starting with 30-40psi in your tires. (We love the SKS Digial AirChecker gauge for presta valves, and a dial-type gauge for schrader valves). Heavier riders or riders who have a rougher riding style should err on the higher side of the pressure range to start. Methodically lower your tire pressure in 5psi increments until you feel as though the tires are not stable in corners, you feel as though you’re hitting the rim on every trail obstacle, or you get a pinch flat (make sure you are carrying the proper equipment to repair a flat tire and get out of the woods). When any of these occur, it’s time to air your tires back up 3-5psi and keep that value in mind for the next ride. It may take a few rides and some experimenting with your pressures until you find the optimal setting for your bike & style.
A tubeless set-up on your mountain bike allow you to run MUCH lower pressures, allow your tires to conform even more to the terrain, and provide the ultimate performance in cornering, climbing and a smooth, fast ride. Your rims and tires need to be designed to be set up as tubeless system, and you will also need special valves, rim strips or tape (depending on the system), and tubeless sealant.
A quick survey of some of our staff & set-ups they run look like this:
- Bill: Uses tubes- Salsa Bucksaw- 9psi front & rear, Salsa Mukluk- 7psi front & rear, Salsa Spearfish 29er – 24psi front / 27psi rear
- Katie: Tubeless on Salsa Spearfish 29er – 17-20psi front & rear
- Matt L: Tubeless on Salsa Horsethief 29er – 16-17psi front, 17-18psi rear depending on terrain
- Jake: Tubeless on 29er hardtail – 20-22psi front / 22-24psi rear
- Gary: Tubeless on carbon Trek Fuel EX – 16-17psi front / 19-22psi rear
Next time we’ll delve into tire pressures for road bicycles, path bikes and their specific considerations. Thanks for reading! Share your persona tire pressure experiences in the comments below or ask any questions you might have.
Editor’s note: Pedal Power fully understands that there are some other variables that can also affect tire pressure, like rim & tire width, tire type, sidewall stiffness, terrain, what season or weather you’re riding in, etc. It’s a tall order to run down every variable out there, and we simply can’t chase every one. Consider this a primer to getting started with experimenting with your air pressure to change how your bicycle handles different terrain & go from there to find your optimal pressures.