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 hole. Another common problem: The pump head doesn't fit the valve on your bike. To prevent this from happening, you will find everything you need to know about bicycle valves and the different common types of valves on the market in this part of our tire series and how to buy the right air pump for them.
What is a bicycle valve anyway?
↪ Short version: The valve lets air into the tire but not out
Let's start from the beginning: There is air in your bicycle tubes. To pump them up, each 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. The actual valve is inside the valve stem.
The bicycle valve is a check valve, air can be pumped in using a bicycle pump. When there is enough pressure on the tire, the valve closes and the air cannot escape.
From here it gets a bit more complicated because you will find different valves on bicycles.
Which valve does my bicycle have?
Which 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:
- The hole in the rim has a 6.5mm diameter. Then a French valve fits.
- The hole is 8.5mm wide, 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 will explicitly state 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, 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.
You can also buy bicycle valves with a bent valve stem. This makes pumping easier, especially for very small wheels, such as on children's bicycles or wheelbarrows. That's why tubes in small sizes, such as 12 inches or 14 inches, often have angled valves.
What types of bicycle valves are there?
↪ The three types of valves, advantages & disadvantages, and handling
There are mainly three types of valves on bicycles: Schrader, Presta, and Dunlop.
As is often the case with bicycle parts, unfortunately, there is no uniform designation. Here is a small table with alternative names for the different bicycle valves and the most important distinguishing features:
Valve |
Presta Valve |
Schrader Valve |
Dunlop Valve |
|
Other names |
Sclaverand Valve, French Valve, Racing Bike Valve |
Auto Valve, MTB Valve, Motorcycle Valve |
Standard Valve, Bicycle Valve, Blitz Valve |
|
Abbreviation for the bicycle valve |
SV, RV |
AV |
DV |
|
Rim hole diameter |
6.5mm |
8.5mm |
8.5mm |
|
Allowed pressure (also depends on model and manufacturer!) |
15 bar |
10 bar |
6 bar |
|
Which bicycle? |
commonly on racing bikes and MTB |
often used on mountain bikes |
on everyday bikes like city bikes, trekking bikes, and children's bicycles, on older bikes |
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 can be filled very easily, 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 lock nut and the valve insert, insert the valve through the rim hole, and then screw both back on tightly. However, the maximum allowable pressure here is only 6 bar, but for most everyday bikes and trekking bicycles, this is sufficient. The design does not allow for an exact measurement of the pressure inside the tube.
The advantages of the Dunlop valve:
- uncomplicated handling
- stable construction
- widely used and compatible with most pumps
The disadvantage:
- the air pressure cannot be measured accurately here
- low permissible air pressure
The Schrader Valve
As the name suggests, the Auto-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 simply inflate a bicycle tire with an auto/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.
An auto valve has a diameter of 8mm and fits in an 8.5mm rim hole, it withstands 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 sometimes cannot 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 shaft
How is an auto or bicycle valve mounted and inflated?
The installation of these two valves is very simple:
- In both cases, you remove the locking nut, and with the bicycle valve/Dunlop valve, you 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 being lightly screwed on by hand.
- Under no circumstances should it be tightly fastened with a tool; it should only prevent the valve from slipping into the rim while 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 is therefore particularly suitable for narrow wheels, such as racing bike tires. Mountain bikes are also increasingly equipped with Presta or Sclaverand valves, as the smaller drilling 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. 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 corresponding other 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 drilling weakens the rim less
- allows for high tire pressure
- the 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 plunger 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 locking nut must be unscrewed, then the valve can be pushed through the rim hole. Afterwards, the locking 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:
- Unscrew the cap from the valve.
- Unscrew the small ring at the tip of the valve a few turns.
- 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 might be a bit tight. However, it usually loosens with little pressure. Some air will escape in the process.
- Push the head of the pump as far as it will go onto the bicycle valve. Some air may escape here too. It is important to push the pump far enough onto your bicycle's valve; otherwise, the bicycle valve won't open, and no air can be pumped into the tube.
- If the pump has a lever, you can now secure it with it.
- Now the pump is securely attached to the bicycle valve, and you can inflate your tire to the desired pressure.
- You can now remove the pump from the valve.
- Finally, the ring is screwed tight again, and the cap goes back on the valve.
When inflating a tube with a French valve, you should consider the following:
- Make sure to push the pump straight and without tilting onto the valve.
- If the tire is not inflating or is difficult to inflate, you may not have unscrewed the valve stem far enough.
- Even when removing the pump from the valve, you should be careful not to tilt or move it too much. The tip of the valve is quite delicate and can bend or even break.
Which valve does a bicycle tube need to fit?
↪ The drilling of the bicycle rim determines which valve fits
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. In the specifications of the rims, 6.5mm or 8.5mm are given, where 6.5mm is only suitable for Presta valves, and in rims with an 8.5mm large hole, all tubes fit.
If you want to install a tube with a narrow Presta valve into a rim with a large hole, you can prevent the valve from sitting too loosely with a valve nut or rim nut. However, this is more of a stopgap 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. This depends on the height of your rims, as the valve must, of course, protrude far enough from the rim so that the bicycle pump can grip it. 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?
↪ Make bicycle valve compatible with accessories
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 search for tubes with a particularly long valve or install a valve extension.
The valve extension makes inflating easier with 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 fixes the valve in the rim hole. If you want to install a new or freshly patched empty tube, this is very helpful because the tube cannot slip away when you attach the pump.
The Valve Cap
New tubes come with a valve cap on the valve, which you should screw back on after inflating. If it's missing, it's not a big deal, but the fine French valve is well protected by the cap. Other valves also collect less dirt under the cap. The cap is especially important on spare tubes! There are indeed reports of valves that have pierced through 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 installed in 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 purchase pump heads or attach an adapter. Image © SKS
The Dreaded Valve Tear
A bicycle valve that suddenly tears off... doesn't sound nice and luckily doesn't happen too often. If the valve is not straight in the rim hole, it can tear off under pressure at some point. The reason for this can be improper installation. However, the tube can also “wander”; this happens if the lock nut was forgotten.
Even a Presta valve in a large hole can detach in this way.
Most of the time the valve doesn't completely come off, it tears, and the air escapes more or less suddenly depending on the size of the damage. In this case, there is only one thing to do: remove the rest of the tube. Look at the rim hole of your rim. Is it very sharp-edged? Then it might be able to be smoothed. Then you need to insert a new tube.
How do I find the right bicycle pump for my valve?
↪ Attention! There is a suitable pump for every 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 to keep the pump in place and prevent damage to the valve.
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. Adapters are available for the other two valves. For the high pressure pumped into road bike tires, the 5 to 7 bar that a gas station compressor achieves is often not sufficient!
So which bicycle valve is the best for your bike?
If you ride a road bike, a French valve is usually the only option, as most narrow rims have a small hole, so the question is already answered. It is similar on a Gravel Bike.
On an MTB, you have the choice. Do you want the greater stability of rims with a small hole, i.e., a Sclaverand = French valve? Or do you want the sturdy 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, children's bikes, and trekking bikes.
If you travel a lot, a car valve is quite practical, as it can be topped up at any gas station. Therefore, car valves are often mounted on trekking bikes and touring bikes, as well as 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:
