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A Presta valve adapter converts a Presta valve into a Schrader valve, but why would you want that?
Among all pneumatic products requiring inflation, only bicycle tires ever use the Presta valve. One of its few redeeming features is that it perfectly complements a skinny road wheel in looks. But it can be a troublesome thing.
The Presta valve has a fragile pin prone to bending or snapping, and removable cores, when present, can become loose and leak air.
The Schrader valve is more robust than a Presta valve, and it’s near universal.
What is a Presta Valve? How Does it Differ to a Schrader (Mountain Bike) Valve?
The Presta valve was invented in 1880 by Monsieur Sclaverand, who worked for French company Morin.
Together with another firm, Morin became Zéfal. Thus, the Presta valve is also known as the French valve or the Sclaverand valve.
Photo: Presta valve
A German American named August Schrader invented the Schrader valve in the 1890s. It was created for the bicycle tire, later becoming the standard valve on all motor-vehicle tires.
There are important differences between Schrader and Presta valves:
- Closure: A Schrader valve seals air in using a spring-loaded pin, whereas a Presta valve keeps air in using air pressure alone. A small nut must be unlocked on a Presta valve before pumping a tire up.
- Width: A Schrader valve is 8mm wide, while a Presta valve is 6mm wide. This is one reason why the Presta is found on thin road wheel rims. It is unwise to compromise the structure of such a rim by drilling a wider hole.
- Removable Core: Schrader valves always have a removable core, whereas not all Presta valves do. This is ideal for feeding sealant into tires. In a Presta valve, you also need a removable core when fitting a valve extender.
Presta Valve Adapters Explained
A standard Presta valve has an external thread, so it’s a simple matter to screw a valve adapter onto it. This enables connection with Schrader pump heads and hoses, bridging the gap in diameter between the two.
Once you’ve pumped the tire up to the required pressure, you’d typically remove the adapter and let the Presta’s pressurized seal do its job.
The Presta adapter is so portable that it makes sense to carry one in various situations.
Imagine you’re touring on a road bike. By carrying an adapter, you improve your chances of getting your tire pumped in an emergency, even at a gas station if necessary. And it may enable you to help other cyclists needing tire inflation.
Another place where you might want a Presta valve adaptor is at home, where you could already have other bikes or vehicles using Schrader valves. With an adapter, you can use the same pump that you use elsewhere.
You can even cheat with a compressor or industrial inflator, taking care not to exceed the maximum pressure of the tire and rim.
Read more: How to use a bicycle pump
Video: How to use a Presta valve adapter
How to Inflate a Presta Valve Using A Normal Pump or Gas Station Pump
Most cyclists are going to pump up their tires before a ride and take a pump with them for emergency use, but anything can happen out on the road.
Below is some advice on how to inflate tires with Presta valves, either with a pump or at a gas station.
With a pump
1: Unscrew the Presta valve nut and give the tip a couple of taps to let out a little air. If you don’t do that, you’ll find the seal sometimes refuses to let air in. Screw the adapter in at this point if you’re using one and attach your pump.
2: Ensure when you attach a push-on pump head to a Presta valve that you put it on straight, otherwise you may gradually bend the valve core until it breaks off. (Same thing when you detach the pump head – pull it backwards and not sideways.) Paying attention here preserves the lifespan of the tube.
3: A small amount of air may escape when detaching a pump from a Presta valve. This is normal. If it has one, make sure the valve’s removable core is tightly done up. You can tighten it with a small valve core wrench.
4: Whatever type of pump you use, it’s important to push and pull it to the full extent of its travel. It is only towards the end of each stroke that air enters the tire. This is the point where pressure in the pump exceeds the tire pressure. Stopping the stroke short creates a disproportionate amount of extra work.
5: Once you’ve reached the desired tire pressure, assuming you are monitoring that, remove the pump head or hose and do the nut up on the Presta valve. Replace the cap if you wish, though that’s more useful on a Schrader valve because the vital air-sealing components are exposed.
At a gas station
1: First, read the instructions on the air machine to determine maximum pressure. It might be the case that you can’t achieve enough pressure if you have a thin road tire. If it looks possible, screw the Presta valve adapter onto your Presta valve after first releasing a little air from the tire (if there is any).
2: Enter a target pressure if the machine is digital. It’s unwise to enter the tire’s max pressure, as the way these machines often work is to overinflate slightly then back up. Allow a minimum leeway of 10 PSI. Some air machines have an analog gauge near the nozzle.
3: Fit the nozzle onto your valve and inflate in the shortest bursts possible. Why? Even though the pressure of your bike tire is likely higher than that of a motorbike or car, it doesn’t hold anywhere near the volume of air. It’s the flow of air entering the tube and tire that you need to worry about.
4: When you’ve reached the desired pressure, remove the nozzle. The danger with a gas station air machine is that you may blow your tire and damage the wheel rim, scaring yourself in the process with the noise. Do not try it if there is no way to track pressure. A portable pressure gauge is handy to have.
Some air machines warn against pumping bike tires, while others permit it up to 60 PSI. That’s a rideable pressure on many road tires, even if it’s sub-optimal.
Can You Inflate a Presta Valve Without an Adapter?
What if you’re out on a ride, have no serviceable pump or Presta valve adapter and need to pump your tire up? Or maybe you’re at home with a multi-valve pump head, and the Presta side of it expires just before a ride?
Here’s a common hack using a plastic Presta valve cap:
1: Cut the tip off a plastic Presta valve cap.
2: Screw the lower part of the cap onto the valve upside-down.
3: Attach a Schrader push-on pump head and pump up your tire.
Video: How to use a Presta valve with any pump
A Presta valve adapter offers a more robust and universal way of pumping up a high-pressure tire.
Not only could it get you out of a fix, but it might also extend the lifespan of a twin-headed pump head or hose. Surely that’s worth two bucks?
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