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The biggest performance improvement you can make to your bike isn't a lighter wheelset or a fancy electronic change. In fact, it's not an upgrade at all—and it shouldn't cost you more than some time, probably less than you'd spend on a new roll of handlebar tape.
It compresses bicycle tires. If you don't pay attention to inflation, the amount of air in your bike's tires is probably not just perfect, it's wrong enough to cause flats and serious drops in performance and comfort. Here are our experts' top tips for finding the perfect bike tire pressure.
- Proper tire pressure allows your bike to roll quickly, ride smoothly, and avoid flats. Narrow tires need more air pressure than wide tires: road tires typically require 80 to 130 psi (psi); mountain bike tires, 25 to 35 psi; and hybrid tyres, 40 to 70 psi.
- To find your ideal pressure, start in the middle of these ranges, then take your body weight into account. The more you weigh, the higher the tire pressure should be. For example, if a 165-pound rider uses 100 psi on his road bike, a 200-pound rider should run close to 120 pounds, and a 130-pound rider can get away with 80 pounds. Never exceed or fall below the manufacturer's recommended tire pressure.
- Check your bike's tire pressure regularly.
- Tires leak air over time. Properly set up tubeless tires, and tires that use butyl tubes (the most common type), leak much less than lightweight latex tubes. But air leaks out of all the tires, from less than a few pounds per square inch a week to extreme drops overnight. The rate of loss increases with pressure and reaction to external factors such as low temperatures (about 2 percent fade for every 10-degree Fahrenheit drop). Some of us bikers check tire pressure before every ride, others once a week. The important thing is that you develop and stick to a habit of regular check-ups and follow-ups that work for you — if you don't, your pressure is probably wrong most of the time you're going.
- Properly inflated bike tires conform to bumps and absorb shock. An over-inflated bike's tires transmit shock to the rider, sacrificing speed and ride comfort.
- More isn't always better. The general bias is always in over-amplification. The maximum pressure listed on the sidewall is generally high – plus it doesn't take into account any factors that affect tire pressure such as rider size and terrain. Especially if you've recently moved to wider tires, or are about to embark on a ride full of turns and slicks, or riding surfaces like chip seal, you'll want to lower your pressure.
It is very common to simply inflate the front and rear tires identically. But your weight balance is not 50-50 front to back. For road riders, that's 40 percent in the front, and 60 percent in the back in most cases, according to a University of Colorado study. But it can vary: The study found a range from 33-67 to 45-55 among the tested athletes.
This means that the pressure you prefer will depend on a variety of things including tire choice and riding style, but it's also clear that you shouldn't be running the same pressure front and rear. If you weigh 150 pounds with a 40-60 weight distribution, that's 90 pounds at the rear wheel and 60 pounds at the front. So it makes sense to apply relatively less pressure up front. It won't be 50 percent less, but it's not unreasonable to think it could be 15 to 20 percent less.
- If the tire pressure is too low, more energy will be lost in the deformation of the tire casing and the friction between the tire and the road. It also increases the chance of punching flat holes.
- If the tire pressure is too high, the tire will be too stiff and your bike will start to vibrate due to imperfections in the road surface, which will negatively affect comfort and waste energy.
- As a caveat, it's important to adhere to the pressure limits set by manufacturers for both your tires and your tires, particularly with regard to the upper limits. These are usually printed on the tires or the sidewalls of the rim.
Although most bicycle tires are labeled a specific size, such as 700 x25c , the actual inflated size for any given tire will depend on both the tire design and the inner width of the wheel.
Most new tires are now designed to the latest 2020 ETRTO (European Tire and Rim Technical Organization) standards with an inner rim width of 19mm, so wheels with a wider inner rim width are more likely to increase this measured tire width when inflated to a certain pressure (and vice versa ).
Also, the nature of the road you take has an important role in determining tire pressure. For example, if you are riding on a completely smooth track , higher pressures are faster. However, on imperfect surfaces, such as roads, pressures that are too high simply increase vibrations and can slow you down.
As the roads get rougher, with larger holes and bumps, the optimum tire pressure drops further.
When the roads get very rough, smaller tires (i.e. 25mm or smaller) running at relatively low pressures may not be able to provide sufficient rim or inner tube protection - especially for heavier riders - which can lead to pinch flats or even rim damage.
- High temperatures, whether ambient or caused by rim braking, can increase tire pressure.
- If you're riding long descents on hot summer days on a bike with rim brakes (especially those with carbon clincher wheels or latex inner tubes), be careful not to over-inflate your bike's tires. Doing so could cause dangerously high pressures to build up inside the inner tubes or tubeless tyres, if too much excess heat is introduced to the system.
