Bent Presta Valve Core? 4 Ways To Fix It (With Pictures)

Presta valves are typically found on road bikes and high-end mountain bikes. They’re thinner and work a little bit differently than a Schrader valve.

One of the main reasons to use a Presta valve is that they require a smaller hole, which gives you a stronger rim. But, on the other hand, the valve itself can be a little bit more fragile, and if you’re not careful, your Presta valve can get bent. 

This article will talk about what happens when your Presta valve gets bent. Then, we’ll look at some of the options you can choose if your valve gets bent and how you can tell if your valve is leaking. But first, let’s take a quick look at how to use a Presta valve. 

How to Use a Presta Valve

A Presta valve is a thin valve with a tiny nut at the end, sometimes called the valve pin. You gently unscrew the valve pin. If you push it in, the air from your bike tire will flow out. Put the coordinating head of the tire pump onto the Valve stem and pump it up. Carefully remove the head of the pump, so you don’t damage the pin. 

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Then, gently screw the top of the valve in just enough to keep it in place, then replace the dust cap or stem cap. 

It’s very easy for the Presta valve to get bent when pumping up your tires. It can even happen when you’re riding, especially if you don’t put the stem cap back on. 

What to Do If Your Presta Valve Is Bent? 

Most Presta valves are made from brass, which is very soft and easy to bend. So if you aren’t careful when using your bicycle pump or screwing on your dust cap, you can easily bend the Presta valve a little bit. But don’t panic- there are options! 

1.     Check if it holds air

If your Presta valve is holding air and you can still pump it up easily, you might not have to do anything at all. As long as it is working, you can keep using it if the valve core is a little bit bent.

The most likely culprit of a bent valve core is pulling off the bike pump head from the tire. If you don’t remove it carefully and straight, it can bend the core. 

I have had several tires with bent Presta valve cores, which worked perfectly well. They do look a little odd since you intuitively know that the core should be straight, but bent cores aren’t inherently dangerous.

If doing nothing makes you nervous, just make sure you bring a spare tube with you. Then, if the valve begins to leak air on a ride, you can just stop and replace the tube like you would for a typical flat tire. Or, if your tires are tubeless, you can easily remove and replace the valve core with a new one (provided you have one along!). Then, you’ll just need to pump the tire back up afterward.  

2.     Fix it

If the Presta core is leaking air because it’s bent, you can try to straighten it out. You’ll need to do this very gently because the valve core is fragile and can break easily if you bend it too far.

First, loosen the nut on the valve stem. However, don’t loosen it too far because this can cause more damage. 

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Next, use a small pair of pliers and gently apply pressure to straighten the valve core. Again, be as conservative as possible because you don’t want to risk breaking it. You just want to straighten it enough to make it work again. 

Try pumping up the tire, then tightening the nut on the end of the valve. Listen carefully to see if the valve is holding air. 

The valve doesn’t have to be perfectly straight – it only needs to be straight enough to hold the air in your tire. 

3.     Replace it

If you can’t fix the valve core, or if it breaks while you are fixing it, you might be able to replace it. Most tubeless tires and even some tubes have removable stem cores. You can purchase a small bag of stem cores very inexpensively. If yours is removable, you might want to add one to your saddlebag with your other flat tire repair items. 

You know that your Presta valve core is removable if you see a small gap between the stem and the core. If there’s no gap, the core can’t be removed.

Use a valve core remover tool to twist off the valve core. If you don’t have one you can use pliers instead. Put a new one in the stem and finger tighten it. Make sure the threads line up so that the valve core is straight. If you try to twist the core in, and it isn’t lining up correctly, you could cause more damage. 

Use the valve core tool to tighten the stem core just enough. 

Loosen the nut at the end of the valve stem and pump up your tires to make sure the tire is holding air. Then tighten the nut and replace the stem cap. 

4.     Replace the entire tube

If your stem core breaks and your tube does not have a replaceable valve core, you’ll have to replace the entire tube. But it’s better to replace the tube than end up stranded with a flat tire! If this is a recurring problem for you, you may want to consider switching to tubes with removable stem cores or going tubeless.  

What To Do If Your Entire Valve Stem is Crooked? 

If the entire valve stem is crooked, it could be because the tube inside the tire isn’t seated correctly. If you ride with the stem crooked, the rim could cut into the valve, causing a hole in your tube and a flat tire. 

You might be able to fix your crooked stem just by letting all the air out of the tire, making sure the stem is straight, and pumping it back up. This might be enough to fix the crooked stem without too much effort. 

If the stem is still crooked, though, you’ll need to unseat the tires on the wheels and adjust the tube inside the tire as if you were changing a flat. 

How Can You Tell if Your Presta Valve is Leaking Air? 

If your bicycle tire is mysteriously going flat, your Presta valve might be leaking air. If you remove the dust cap from your Presta valve, you might be able to hear or feel air coming out of it. If your tires are tubeless, you might be able to see sealant squeezing out around the arts of the valve core. In this case, you’ll probably need to replace the core or the tube. 

Sam Benkoczy

Hi, I'm Sam. I own and maintain 6 e-bikes, 15 regular bikes (road bikes, folding bikes, hybrid bikes, city bikes among others). I learned about bikes from my local bike mechanic as well as from bike maintenance courses. I love being out there in the saddle, and using my bike as a practical means of transportation. You can also find me on my YouTube channel at Say hi to me at

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