Why can't my Schrader valve be pumped?

Season tips

Insufficiently inflated tires require a greater effort from the driver. Often you are not even aware of this and believe that you are no longer in shape! The same "drop in performance" also applies to e-bikes: If there is not enough air in the tires, the motor and muscle power have to use more energy. That's why more electricity is needed to drive ...

3 valve types

If you haven't used your bike for several months, it can happen that the tires are so flat that you think they are broken. However, it is quite normal for the air to gradually escape from the tires. Difficulty inflating can be related to the valve, but there are usually very few problems with solving them. There are basically three different types of valves, and for all three there is a trick to either loosen or repair the valve before the air pump is connected (see below or on the page Inflating bicycle tires).

Presta valve (Sclaverand valve): first unscrew the small nut on top of the valve a little (but do not unscrew completely), then press on the valve to loosen it - if there is still air in the tire, you can hear it hissing.

Schrader valve (Auto-valve): Before inflating, release the valve by pressing the small pin with your finger, a key or the back of the valve cap - if there is air in the tire, you can hear it hissing.

Dunlop valve: If the air does not stay in the tire while pumping - or the tire suddenly loses air during inflation, unscrew the valve and check the small rubber tube that is pulled over the valve. It should cover the small hole in the valve. If it is torn, dry or has fallen into the tire chamber, it must be replaced (included in the tube repair set). Sometimes the old one can also be used again: turn it so that the intact area closes the hole.
Danger: only unscrew the valve when the air chamber really does not contain any air, otherwise it could be thrown away by the pressure!

A good air pump with a pressure gauge

To inflate a bicycle tire you can of course use the small pump that you usually get when you buy a new bicycle. Its main purpose is to fix a flat tire while riding, but it is less suitable to keep the bike in good condition. If you use your bike regularly, you will not regret buying a solid air pump that is easy to use. Models that are held with the foot on the ground have proven themselves (see photo above). Make sure the tubing has interchangeable valve heads that fit all three common valve types. Air pumps with integrated are a very useful extra manometer, i.e. with a pressure gauge that shows the air pressure in the tire. Air pressure is usually expressed in two units: in bar and in PSI (pounds per square inch)

1 bar corresponds to approximately 14.5 PSI
100 PSI corresponds to about 7 bar

With the optimal tire pressure on the go

The more a tire is inflated, the less the wheels will flatten under the weight of the driver. This reduces the contact area between the tire and the ground: the bike runs well, the rolling resistance on the tar is low, and you ride quickly with less effort. If the tires are inflated too much, however, they become so hard that they bounce over bumps in the ground instead of cushioning them. These vibrations are not only detrimental to comfort - they also require more effort from the driver and thus lead to a decrease in performance. In addition, the bike is more difficult to steer and brakes less well, especially on wet roads.

Optimal tire pressure is therefore a compromise between performance and comfort. It varies depending on the type of tire and the weight of the driver. The narrower the tire, the less air it can hold, which is why its optimal tire pressure is rather high. The heavier the driver, the more the tire should be inflated.

Mountain bike fans, on the other hand, only inflate the tires of their off-road bikes slightly (2.5 to 3 bar), because they are supposed to cushion the obstacles, stick to the slopes and brake well. Racing cyclists choose a pressure that is up to three times higher (7 to 9 bar), because they must first and foremost maximize the performance of their muscular strength.

If you ride a bike in the city, you usually roll on tar. The optimal tire pressure for this is usually between 3.5 and 6 bar, depending on the type of tire and weight.

Information on the tire flank

The minimum and maximum tire pressures specified by the manufacturer are printed on the side of the tire. It is usually given in two units: bar and PSI (pounds per square inch). Note that "inflate" means to inflate in English. The heavier you are, the more you benefit if you inflate the tires to the specified maximum. Be careful, however, because tires with excessive pressure can burst! Therefore, keep an eye on the pressure gauge of the pump and the tire when inflating - this will prevent it from cracking. Wear, solar radiation and environmental pollution (nitrogen oxide and ozone) make the tires less durable over time.

If you feel the uneven ground uncomfortably after inflating, you can always let some air out of the tires to increase your driving comfort. This is also recommended when taking a drive on dirt roads.

If you have to change a tire, compare the tire pressure of the different models and choose one that can withstand more bar or PSI for the same size, especially if your bike has to carry more than 70 kg. This is especially true for the rear tires of city bikes, as they take up almost two thirds of the weight.

Inflate the tires regularly

As mentioned above, even bicycle tires in good condition can lose air, up to 0.5 bar per week. In order to keep your exertion within limits and also so that you do not lose the pleasure of driving, the tires should be inflated regularly, but at least every two weeks. With a good pump, this can be done in no time.

Inflate Bicycle Tires, an interactive page on this Internet site.

PDF 3.7 MB leaflet "Inflating Velopneus", which can be hung in the bike room, for example.

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