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 on 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.
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. 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 in the tire, the valve closes and the air cannot escape again.
From here it gets a bit more complicated, as you will find different valves on bicycles.
What valve does my bike 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 large, then car valve and Dunlop valve 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, with a little practice you can immediately recognize which one is on your bike.
> If you only have a rim (without an old tube with a valve), you can also simply measure the hole.
You can also get bicycle valves with an angled valve stem buy. This makes it easier to inflate particularly small wheels, such as children's bicycles or wheelbarrows. Therefore, tubes in small sizes, like 12 inches or 14 inches, often have angled valves.
What types of bicycle valves are there?
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 their main distinguishing features:
Valve |
Presta Valve |
Schrader Valve |
Dunlop Valve |
|
Other names |
Sclaverand valve, French valve, racing bike valve |
Auto valve, MTB valve, motorcycle valve |
Normal valve, bicycle valve, Blitz valve |
|
Abbreviation for the bicycle valve |
SV, RV |
AV |
DV |
|
Diameter of rim hole |
6.5mm |
8.5mm |
8.5mm |
|
Allowed pressure (also depends on model and manufacturer!) |
15 bar |
10 bar |
6 bar |
|
Which bicycle? |
often on racing bikes and MTBs |
frequently used on mountain bikes |
on everyday bikes like city bikes, trekking bikes, and children's bicycles, on older bicycles |
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 inner workings of a Dunlop valve can also be replaced without tools if it becomes leaky. To insert a new tube, you must first remove the cap nut and the valve core, 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
- sturdy construction
- widely used and compatible with most pumps
The disadvantage:
- the air pressure cannot be measured accurately
- low allowable 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 easily inflate a bicycle tire with an auto/Schrader valve "at the gas station" with the compressor. So you don't have to carry a bicycle pump 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 into 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 to handle
- sturdy construction
- maximum pressure of 10 bar
Disadvantages of the Schrader valve:
- some (older) bicycle pumps are not compatible
- to replace the valve in the valve stem, you need a special tool
How is an auto or bicycle valve mounted and inflated?
The installation of these two valves is very simple:
- For both, remove the locknut, for the bicycle valve/Dunlop valve also the actual valve from the valve stem.
- Then you can push the valve through the rim hole.
- Subsequently, both are screwed back on, with the rim nut only lightly screwed on with the 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 rims, such as road bike tires. Mountain bikes are also increasingly being ridden with Presta or Sclaverand valves, as the smaller borehole 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 road bikes. Since the valve stem is 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 unintentionally releasing pressure. It is – and this doesn’t sound world-shattering, but is always appreciated on road 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 borehole weakens the rim less
- allows high tire pressure
- tire pressure can be reduced without tools or a pump
- a few grams lighter than other valves
- air pressure can be precisely adjusted
The disadvantages of the French valve:
- the plunger at the tip of the valve is quite thin and 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 too tightly.
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 may be a bit tighter. However, it usually loosens with little pressure, releasing some air.
- 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 valve; otherwise, the bicycle valve will not open and air cannot be pumped into the tube.
- If the pump has a lever, you can now fix it with it.
- Now the pump is securely seated on the bicycle valve, and you can inflate your tire to the desired pressure.
- You can now pull the pump off the valve.
- 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 and without tilting onto the valve.
- If the tire does not inflate or is difficult to inflate, you may not have unscrewed the valve pin far enough.
- Even when you pull the pump off the valve, you should make sure not to tilt or move it too much. The tip of the valve is quite delicate, it can bend or even break.
What 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 state 6.5mm or 8.5mm, with 6.5mm only suitable for Presta valves, and in rims with an 8.5mm hole, all tubes fit.
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 not recommended to use a narrow valve in rims with a large hole, because 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 use a valve extension to adjust the length of the valve to the rim wall or use the valve or lock nut to secure the valve. Here are some of the most important accessories for bicycle valves:
The valve extension
You can buy bicycle tubes in different valve lengths, there are valves with 48mm or 36mm lengths, 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 pump up the tire. In this case, you can look for tubes with an especially long valve or attach a valve extension.
The valve extension makes pumping easier for 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, cap 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, as it prevents the tube from slipping away when you attach the pump.
The valve cap
New tubes have a valve cap on the valve, you should screw it back on after pumping. If it's 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. However, the cap is particularly important on spare tubes! There are actually reports of valves that have pierced through the wrapped tube, 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 "move"; this happens when the locknut was forgotten.
A Presta valve in a large hole can also detach 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's only one thing to do: 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, then the smaller hole fits French valves and bicycle valves (Dunlop), while the larger opening allows you to inflate car valves.
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 with French valves, a pump with locking (i.e., a locking lever) is recommended to ensure the pump holds and the valve is not damaged.
You can inflate car valves with a corresponding floor pump or hand pump, but you can also ride your bicycle to the gas station and use the compressor there. For the other two valves, there are adapters. For the high pressure that is pumped into road bike tires, the 5 to 7 bar that a gas station compressor can achieve is often not sufficient!
Which bicycle valve is the best for your bike?
If you ride a road 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 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, on children's bikes and trekking bikes.
If you travel a lot, a car valve is quite practical, as 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:
