Tire Pressure: When Lower Is Not Always Better
In 2006, Krista Rust left her job as an Electrical Engineer for Motorola to race her bike, and she's been traveling, riding, and helping people keep their bikes rolling ever since. Krista is an ambassador for the benefits of tubeless and has spent years helping riders make the switch from inner tubes. Originally an XC racer and now on the enduro scene, Krista lives a life on the road traveling and racing around the world. We've asked her to weigh in on some of the most common questions people ask about tubeless performance.
What tire pressure should I ride? It’s a question we’ve all asked at some point. Most of us now realize tire pressure that's too high compromises traction and control and actually make a bike roll slower. But it's also possible to run too low a pressure. Finding your ideal tire pressure isn’t simple and varies based on setup, conditions and riding style, but in this new series of articles, we share the expertise of enduro mountain bike pro racer Krista Rust. Read on for Part 1 of what Krista has to say about tire pressure.
I am often asked what tire pressure I run and what tire pressure I would recommend to others. The answer is not a specific number. Instead, it is whatever pressure allows a particular tire to conform to terrain and is supportive.
The only time a numerical value is used to set tire pressure is after defining the perfect feel for a given tire casing, volume, rider style, rider weight, terrain, etc. Then and only then can one use a number to replicate ideal tire pressure. Of course, this is only applicable while all variables remain constant. You have to be using the same pump so you get a consistent read on pressure. You must continue to use the same kind of tires. Your weight and your riding style must not vary.
Lower tire pressure is not always better. Not only can it drastically affect your cornering, but it’s also no substitute for properly adjusting your suspension.
Trusting Your Tires and Looking Ahead
You make up time by cornering aggressively. Cornering correctly allows a rider to hold speed and momentum in a corner instead of grabbing brakes, slowing down and then having to pedal out. When pedaling is saved for flats and uphills, a rider will be that much fresher or that much faster, whichever is more important.
Cornering on a tire with too low pressure causes the tire to lose its supportive shape and get “squirrelly”. As soon as that happens, cornering confidence disappears. The rider feels the instability and immediately looks at the ground in front of them, stands the bike up and reaches for the brakes.
Your goal should be to lean the bike, look through the turn and commit; be confident that the side knobs and proper body positioning pressure will allow the bike to hold the line. Controlled drifting is included in this. As soon as the tire collapses or starts to fold, it’s over.
Unless You Ride a Rigid Bike, Tire Pressure is Not Suspension
The biggest mistake I see is a rider not dialing in or custom-tuning his or her bike’s suspension. If the suspension is valved too stiffly at some point in its travel, a rider will tend to soften the tires to compensate.
For the best setup, tune suspension correctly AND set up tire pressure correctly. Before I figured this out, I tended to decrease the air in my suspension to soften my ride through the rough stuff, but then my fork would dive in corners or on steep, steppy terrain.
Making this common mistake robs a rider of confidence as a diving fork throws a rider’s weight forward and steepens the head angle. Then the rider grabs brake levers which causes the fork to dive more, further shifting more weight forward and resulting in less ability to control the bike, more braking and a never ending spiral of bad things happening.
Add in squirrelly tires with too little pressure in them to this, and things may end badly.
Avoid Flats and Prevent Rim Damage
Riding with too low tire pressures makes you more susceptible to bottoming out and possibly damaging your rims, and you may also get flats more frequently.
Stay tuned for Part 2 of our series on tire pressure!
All photos by Kenny Wehn.