Many valve types have been invented since the invention of pneumatic tires. But for bikes mainly, Presta and Schrader are still in use.
The Presta Valve is the slimmer of the two and it is a bit more complex to use because it uses a lock nut rather than a spring for closure.
Originally, Presta valves were used in sports and racing bikes because they were slim and allowed racers to pump tires using a pump attached with chunk without a hose.
Presta valves are relatively easier to pump because there is no valve spring to deal with. Although valve depressors designed for Schrader valves can also be used to alleviate this, a check valve would be required.
The small diameter of the Presta valve needs a smaller hole in the rim. The size is relevant for narrow rims where cross sectional strength is greatly reduced by a stem hole. In narrow rims, the space left between tire beads for wider Schrader valves by clincher tires is insufficient.
In contrast, Schrader valves are more universally used. They are larger, more robust and have an easily removable core. They are easier to use because of the spring closure mechanism, which means you only need to press the inflation chuck (that is, the pump head) onto the Schrader valve at an automobile service station. For hand pumps, a screwed or lever chuck makes the valve depressor. The depressor makes inflation easier, and is also necessary to read back pressure in the tire.
Although Presta valves have been made with removable cores, these types of Presta valves are very uncommon. A Presta core is removable if it has two wrench flats on the coarse valve cap threads.
There is no general syllogism of which is better because it has more to do with the type of bike and the biker’s preferences. However, the major differences and advantages of each over the other are discussed below.
Advantages of Presta Valves Over Schrader Valves
1. They’re slimmer and require smaller rim holes, which enhances strength.
2. They can be extended with adaptors which makes them good for deeper-section aerodynamic rims.
3. They’re lighter, which enables balance for the stem weight to spin smoothly.
4. They seal tightly without mechanical check valves. (Schrader valves on the other hand, need a mechanical check valve to seal tightly.)
5. Presta valves are easier to pump.
Advantages of Schrader Valves Over Presta Valves
1. They have easily removable cores.
2. They are more universally used.
3. They are simpler to use because of the spring closure mechanism possessed.
4. Schrader valve allows more air for a tubeless set up.
5. Either valves can be used on Schrader drilled rims.
DIFFERENCES BETWEEN PRESTA AND SCHRADER VALVES
1) Schrader valves are thicker, and can hardy fit through the tube of a road rim. In narrow road tires the space might not be enough for the Schrader valve to fit in.
Presta valves will also need electrical tape, shims or adapters to fit on a mountain bike rim because they are narrower in contrast to Schrader valves.
2) Presta valves are easier to pump with little efforts required. they can be inflated with small capacity hand pumps, due to the fact that there is no spring in the valve. Schrader valves are relatively more difficult to pump as it requires a pump with a mechanism to deflate the spring in the schrader valve.
3. The two valves require different types of pump head, which implies that a Schrader headed pump cannot inflate a Presta tube valve and vice versa.
There is a solution to this as pump head with dual attachments have been invented. This type of pump features both head, thefore, you can use either of the pump head designed for your valve.
4. Schrader valves tube valves are wide and flat on the end. While Presta valves tube valves are narrower and have a locking nut at the top. The locking nut can be loosened to add or release air. Releasing the air is quite easy, it is done by loosening the locking nut then pressing to let the air out.
REPLACING A VALVE
Most valves are attached to the tubes so in most cases you will have to change the tube. However, you can replace valves in cases where you have;
1. Replaceable Cores.
Some Presta valves have the replaceable core that unscrew key for adding tire sealant, or adding valve extenders to aero rim. Replaceable cores are available for sale at almost every local bike shop. Your valve has replaceable cores if it’s sides have small, flat parts right as the valve tapers across the nut at the top.
2. Presta Valves.
Presta valves for tubeless tires are sealed by a knurled nut that fixes the valve to the rim. If the seal happens to fail and is letting air out of your tire, the valve can just be replaced. Some tubeless valves have a specific rim model. Make sure you get the correct replacement, or the gasket might not seal properly.
Because the rims of bicycles drilled for Presta valves cannot contain the wider Schrader valves, drilling the rim is usually necessary for such replacements to be made, which can weaken the rim in a way.
On the other hand, when a Presta valve is fitted into the bigger Schrader rim hole, reducers or grommets are used to fill up the excess space sometimes. The standard Presta valve has an external thread. An adapter can be used to fit the thread to allow Presta valves connect to a pump with Schrader chuck.
The major differences between a Presta and Schrader valves are the diameters. While Schrader valves are larger, Presta valves are rather slimmer and consequently, the valve holes on bicycle rims are drilled to suit a particular size or another.
The major concern with using a Presta valve in a rim drilled for a Shrader valve is not necessarily movement of the valve stem, but rather a hernia of the tube through the excess space at high pressure, causing a blowout.
Most mountain bike tires maintain a low pressure, therefore you might get away with it. However, there is an adapter, also known as a ‘valve grommet’, which is made out of rubber or metal. It helps to make the valve hole small enough for a Presta valve to fit tightly. It will also remain tight when under high pressure.
In conclusion, there is no general consensus on which is better. It all depends on the factors discussed and preferences.