The easiest way to keep your bicycle running well and preventing flat tires is to keep your tires properly inflated. Properly inflated tires ride best, last longer, and resist punctures.
You should check your tires before every ride. Why? Your tires lose air over time, even overnight. How does this happen? The little molecules of air wiggle their way out between the molecules of rubber in the inner tubes and tires. The same thing happnes to your car tires, but it's not as critical because the amount of air lost is so small compared to the large volume of air in a car's tire. But with bicycle tires, a little bit of air makes a big difference. A bicycle tire can lose as much as 10% to 20% of its air in one day.
What happens when there's not enough air in your tires? Besides making your bike not as efficient as it should be, the biggest danger is what's called a "pinch flat." Suppose you run over a pothole, curb, rock, stick, or other sharp obstable. If the air pressure in your tires is too low, the inner tube gets pinched between the tire and the rim, and the edges of the rim cut two side-by-side holes into the inner tube, which is called a "snake bite."
For fatter rubber, such as what's on most off-road bikes, once a week is about right. But DON'T head to a service station and use the car-tire compressor! (They can explode a bike tire in seconds.) Do it with your "floor" (home) pump. Here's how.
Get a "floor" pump with built-in gauge for checking inflation.
Carry a portable pump for fixing flats on rides.
Step 1. Know your valve type
You need to know your tube's valve type to ensure that you purchase the correct tubes as replacements. And, so you know how to set up your pump, how to attach the pump to the valve and inflate the tire.
To add or let air out of Presta valves, you must first unscrew the tip by turning it counterclockwise. To let air out, press down on the tip, which opens the valve. Also, before inflation, press down to make sure the valve is open.
For Schrader valves, to release air, press something into the valve to depress the valve core (the little pin inside the valve). To inflate, simply attach the pump and get to work.
- Presta valves are also called "French," "racing," and "needle" valves.
- Not all Presta valves have threaded shafts as shown; some are smooth metal or rubber.
- Presta valves come in different lengths. Match the length of the valves that came on your wheels. The deeper your rims are, the longer the valves need to be.
- Schrader valves are the same as automobile valves, and are sometimes called "American" valves.
- Valves usually come with plastic caps. These provide a little protection and a "finished" look. But, many cyclists choose not to ride with them because it's easier to inflate tires when the caps are already removed.
Step 2. Attach the pump
There are many different types of pumps and the best way to guarantee using yours correctly is carefully reading the directions. Many modern pumps feature a head that fits both valve types. You simply use the hole that fits on the valve (skinny one for Presta and larger for Schrader).
Some pumps have convertible heads on which you must reassemble the parts when you want to pump up a different valve. If you have this type, set it up for the valves on your bicycle and keep the directions handy so you'll remember how to adapt it when necessary.
It's easy enough to attach the pump to the valve. Be sure to open a Presta valve first by unscrewing and briefly pressing on the tip. And, press the pump head on far enough (cover about one to two thirds of the valve).
If the pump head has a "lever lock," flip it to attach the head to the valve and start pumping (photo).
Tip: Don't pump too vigorously. Slow and steady gets the job done quickly and prevents pump damage (it's possible to harm the gauge by pumping too quickly).
Step 3. Inflate the tire
How much tire pressure should you run? A practical approach is to use the manufacturer's recommended pressure, which you'll find printed on the tire sidewall (it's often on a small label but it might be molded into the casing, too, so look closely). This suggested inflation range is a good starting point. If it's a wide range, for example 40 to 60 psi, experiment to find which pressure works and feels best.
How the tires feel depends on rider weight, too. Check our chart for recommended pressures.
- Many cyclists put too little air in road tires, which makes it harder to pedal, wears the tires prematurely and causes more flats.
- Likewise, many riders use too much air in off-road tires, which reduces traction and control, and creates a harsh ride.