Bicycle valves – everything you need to know!

 

Bicycle valves are tiny – and yet they can cause you a lot of headaches. Especially when your tire is flat. You might even have a new tube ready, but oh dear... the valve doesn't fit through the rim's hole. Another common problem: The pump head doesn't fit the valve on your bike. To prevent this from happening to you, in this part of our tire series, you'll find everything you need to know about bicycle valves and the different common types of valves on the market and how to buy the right air pump for them.

 

What exactly is a bicycle valve?

Let's start from the very beginning: There is air in your bicycle tubes. To inflate them, every bicycle tube needs a valve. The visible part of the valve is a small metal tube that is fitted into the bicycle tube, the connection is vulcanized to ensure it holds and is airtight. This metal tube is the valve stem, it comes in different lengths, shapes, and diameters, which is why there are different bicycle valves. Inside the valve stem is the actual valve.
The bicycle valve is a check valve, air can be pumped in using a bicycle pump. When there is enough pressure in the tire, the valve closes, and the air cannot escape again.
From here, it gets a bit more complicated because you will find different valves on bicycles. 

 

What valve does my bicycle have?

What valve the tube can have depends on the rims of your bicycle. The rim has a hole, and the valve must fit through it. There are two possible variants here:

1. The hole in the rim has a 6.5mm diameter. Then a French valve fits.
2. The hole is 8.5mm large, then car valves and Dunlop valves fit.

> When you buy new rims or wheels, you will usually find a size specification in mm in the specifications, or it explicitly states which valve fits. 

> If you have a complete bike in front of you and don't know what fits, you can look at the valve and simply compare. The three common bicycle valves look different, and with a little practice, you can immediately recognize which one is on your bicycle. 

> If you only have a rim (without an old tube with a valve), you can also simply measure the hole. 

The Dunlop Bicycle Valve

The Dunlop Valve, Bicycle Valve or Blitz Valve is very commonly found on bicycles, it is installed millions of times and tested. Tubes with bicycle valves are very easy to fill, which is their great advantage, especially since most commercially available bicycle pumps fit. The interior of a Dunlop valve can also be replaced without tools if it becomes leaky. To insert a new tube, you must first remove the locknut and valve insert, insert the valve through the rim hole, and then screw both back on. However, the maximum allowed pressure here is only 6 bar, but this is sufficient for most everyday bikes and trekking bicycles. The design does not allow for precise measurement of the pressure inside the tube. 

The advantages of the Dunlop valve:

• easy to handle
• stable construction
• widely used and compatible with most pumps

The disadvantage: 

• the air pressure cannot be measured accurately
• lower allowable air pressure

The Schrader valve

As the name suggests, the car-valve or Schrader valve is not only found on bicycles, it also keeps car tires airtight. This is also the biggest advantage of this valve: You can easily inflate a bicycle tire with a car/Schrader valve “at the gas station” using the compressor. So you don't have to carry a bicycle pump with you if you are willing to push your bike to the nearest gas station in case of doubt. For this reason, it is often found on touring and travel bikes.
A car valve has a diameter of 8mm and fits into an 8.5mm rim hole, it can withstand a pressure of up to 10 bar. To open the valve, i.e., to release the air, you need a narrow object to press the valve pin. Schrader valves can sometimes not be inflated with simple or older bicycle pumps.

Advantages of the Schrader valve:

• Inflating at the gas station is easily possible 
• easy handling
• stable construction
• maximum pressure of 10 bar

Disadvantages of the Schrader valve:

• some (older) bicycle pumps are not compatible 
• you need a special tool to replace the valve in the valve stem

 

How is a car or bicycle valve mounted and inflated?

The installation of these two valves is very simple: 

• For both, remove the lock nut, and for the bicycle valve/Dunlop valve, also remove the actual valve from the valve stem. 
• Then you can push the valve through the rim hole. 
• Afterwards, both are screwed back on, with the rim nut only being lightly screwed on with fingers. 
• Under no circumstances should it be tightened with a tool, it should only prevent the valve from slipping into the rim when inflating.
• Now you can attach the appropriate bicycle pump and inflate.

The French valve

The French valve is also known as the Presta bicycle valve, racing bike valve or Sclaverand valve. 

With a diameter of 6mm, it is narrower than other bicycle valves and therefore particularly suitable for narrow wheels, such as racing bike tires. Mountain bikes are also increasingly being equipped with Presta or Sclaverand valves, as the smaller hole affects the stability of the rims less. These bicycle valves can withstand a very high tire pressure of up to 15 bar, which is why they are traditionally used on racing bikes. Since the valve stem is located outside the valve, it can be easily pressed to release air. On the other hand, if you tighten the small wheel at the tip of the valve after inflating, there is no risk of accidentally releasing pressure. It is – and this may not sound groundbreaking, but it is always appreciated on racing bikes – up to 5 grams lighter than other corresponding valves. The air pressure can be very precisely adjusted here with a pump with a pressure gauge.

The advantages of the French valve:

• the smaller hole weakens the rim less
• allows for high tire pressure
• tire pressure can be reduced without tools or a pump
• a few grams lighter than other valves
• air pressure precisely adjustable

The disadvantages of the French valve:

• the stem at the tip of the valve is quite thin, it can bend relatively easily, for example when removing the pump

How do I inflate my bicycle with a Presta valve?

The installation is similar to other valves. The lock nut must be unscrewed, then the valve can be pushed through the rim hole. Afterwards, the lock nut is screwed back on and not tightened too much.

Inflating a tube with a French valve requires a few more steps than with other valves:

1. Unscrew the cap from the valve.
2. Unscrew the small ring at the tip of the valve a few turns.
3. Press the valve stem (the tip of the valve) twice briefly to loosen it. If your tire hasn't been inflated for a long time, it may sit a bit tight. However, it usually loosens with little pressure. Some air escapes in the process.
4. Push the pump head as far as it will go onto the bicycle valve. Some air may escape here as well. It is important to push the pump far enough onto your bicycle's valve, otherwise the bicycle valve will not open and no air can be pumped into the tube.
5. If the pump has a lever, you can now fix it with it.
6. Now the pump is securely on the bicycle valve and you can inflate your tire to the desired pressure.
7. You can now pull the pump off the valve.
8. Finally, the ring is screwed back on and the cap goes back on the valve.

When inflating a tube with a French valve, you should keep the following in mind:

• Make sure to always push the pump straight onto the valve without tilting it. 
• If the tire does not inflate or is difficult to inflate, you may not have unscrewed the valve pin far enough.
• Even when pulling the pump off the valve, you should ensure that you do not tilt or move it too much. The tip of the valve is quite delicate, it can bend or even break. 

What type of valve does a bicycle tube need to fit?

How do you buy the tube with the right valve? It's not that complicated. 

You need to know the size of the valve opening of your rims, then you will know which valve fits. The specifications of the rims indicate 6.5mm or 8.5mm, with 6.5mm only suitable for Presta valves, and all tubes fit in rims with an 8.5mm hole.

If you want to install a tube with a narrow Presta valve in a rim with a large hole, you can use a valve nut or rim nut to prevent the valve from sitting too loosely. However, this is more of a makeshift solution, and it is advised against using a narrow valve in rims with a large hole, as this combination can damage the tube.

Additionally, the valve length is important. It depends on the height of your rims, as the valve must protrude far enough from the rim for the bicycle pump to grip. If the valve is too short, you can install a valve extension.

For new tubes, the type of valve and the length are always indicated on the packaging and in the product specifications.

Here you can clearly see the valve, so you buy the right tube. Image © Tubolito

When do I need a bicycle valve adapter?

There are different adapters and accessories around the bicycle valve. You can adjust the length of the valve to the rim wall with a valve extension or secure the valve with the valve or lock nut. Here are some of the most important accessory parts for Bicycle Valves:

The Valve Extension

You can buy bicycle tubes in different valve lengths, there are valves with 48mm or 36mm length, but also 60mm or even 80mm valve lengths are available. For particularly high rims, however, this is not sufficient. Many road bike rims, especially aero rims, have a particularly high rim wall. A regular bicycle valve is too short for such high-profile rims, meaning there is not enough valve sticking out of the rim to inflate the tire. In this case, you can look for tubes with a particularly long valve or install a valve extension.

The valve extension makes it easier to inflate particularly high rims. Image © Birzmann

The Valve Insert

If your bicycle valve is leaking, you can continue to use the tube after replacing the valve insert. With a Presta valve with a bent valve stem, you can also replace the valve core.

The Rim Nut

The rim nut, lock nut, or valve nut secures the valve in the rim hole. If you want to install a new or freshly patched empty tube, this is very helpful because it prevents the tube from slipping when you attach the pump.

The Valve Cap

New tubes come with a valve cap on the valve, and you should screw it back on after inflating. If it is missing, it's not a big deal, but especially the fine French valve is well protected by the cap. Other valves also collect less dirt under the cap. The cap is particularly important on spare tubes! There are indeed reports of valves that have been punctured by the tube wrapped around them, leaving bikers stranded with a broken spare tube in the wilderness.

The Pump Adapter

The adapter for the bicycle pump is not directly an accessory for a bicycle valve, but it definitely belongs on our list! Since many bicycle pumps do not fit all three types of valves, you can buy adapters that are built into the air pump.

There are also adapters that allow all three types of valves to be inflated at the gas station.

If your pump is not compatible with all valves, you can buy replacement pump heads or attach an adapter. Image © SKS

The dreaded valve tear

A bicycle valve that suddenly tears off... doesn't sound nice and fortunately doesn't happen too often. If the valve is not straight in the valve hole of the rim, it can tear off under pressure at some point. The reason for this can be improper installation. The tube can also “wander”; this happens if the lock nut was forgotten.

A Presta valve in a large hole can also fail in this way. 

Usually, the valve doesn't pop off completely, it tears, and the air escapes more or less suddenly depending on the size of the damage. In this case, there is only one solution: remove the remaining tube. Look at the valve hole of your rim. Is it very sharp-edged? Then it might be possible to smooth it out. Then you need to insert a new tube. 

 

How do I find the right bicycle pump for my valve?

The pump diameter for Presta valves and Dunlop valves is the same, so a pump fits both valves.

Floor pumps often have two openings, the smaller hole fits French valves and bicycle valves (Dunlop), and you can inflate car valves through the larger opening.

Mini pumps or hand pumps often fit only one valve, but there are also models where the sealing rubber in the pump head can be rotated to cover different diameters.

Especially for French valves, a pump with locking (i.e., a locking lever) is recommended so that the pump holds and the valve is not damaged. 

You can inflate car valves with a suitable floor pump or hand pump, but you can also ride your bike to the gas station and use the compressor there. There are adapters for the other two valves. For the high pressure that is pumped into racing bike tires, the 5 to 7 bar that a gas station compressor achieves is often not sufficient! 

Which bicycle valve is the best for your bike?

If you ride a racing bike, a French valve  mostly the only option, most of the narrow rims have a small hole, so the question is already answered. On the Gravel Bike it looks similar.

On the MTB you have the choice. Do you want the greater stability of the rims with a small hole, i.e. a Sclaverand = French valve? Or do you want the stable valve stem of a car valve and the ability to pump at the gas station?

Because they are robust and uncomplicated, bicycle valves (i.e. Blitz valves or Dunlop) are often found on city bikes, on children's bikes and trekking bikes.

If you travel a lot, a car valve is quite practical because it can be pumped up at any gas station. Therefore, car valves are often mounted on trekking bikes and touring bikes, but also on everyday bikes like city bikes.

So there is no general answer here, each valve has its advantages and disadvantages. 

The blog series that tells you everything you need to know about bicycle tires:

• Find the right tire width for your bike
• How to determine the tire pressure for your bike
• How to determine the tire size for your bike
• Gravel tires – what you should know!
• E-Bike tires – useful or useless?