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Supply chains are unpredictable these days, and that can make bike tubes scarce. You may be wondering whether installing a Presta tube onto a Schrader rim will do the trick.
Or maybe you just have some extra Presta tubes lying around. Either way, if you’re asking this question you’re likely familiar with the differences between the two options. But for the beginners, let’s start there.
Presta vs. Schrader valve
Presta valves, also known as French valves, were designed specifically by the cycling industry to work with the narrow, deep and aerodynamic rims most often found on road and track bikes.
They are slim with a long valve stem, and come with a metal nut on top that must be loosened before you can pump air into it to inflate your bike tire.
Schrader valves are more universal. You’ll almost always see them on a BMX, comfort or hybrid bike. They are the same valves used throughout the motor vehicle industry. They use a check valve system that allows airflow in only one direction.
The most relevant difference for this question is that Schrader valves are wider in diameter, so they need a larger valve hole in the rim to fit through.
Presta tube on a Schrader rim
Physically, a Presta tube will fit into the hole on a Schrader rim. Whether it’s a good idea is another question.
There are plenty of cautionary tales out there that suggest cyclists should avoid doing this. For example, since the opening for the Schrader valve is larger than the Presta valve, you increase your risk of getting dirt, mud and water inside your rim.
Even more concerning is the movement of the valves, and the possibility of tearing the tube. At high pressure, the extra space around the valve increases the risk of causing a ‘hernia’ of the tube, which could cause it to burst.
What if you don’t have any other option but to use a Presta tube in a Schrader rim, at least temporarily?
Many cyclists report being able to get away with the valve replacement, with minimal issues. This seems to be safest with the tube inflated at lower air pressure. If you are willing to risk it, try not exceed 60 psi.
Fortunately, there are other quick fixes you can implement to reduce your risk of getting a flat tire.
Presta valves come equipped with a tension nut to help stabilize the valve. You could place the valve nut under the rim to seal the gap, but you lose stability. Alternatively you could use a second tension nut or a simple washer on the inside of the rim as an internal seal. However, this will prevent the tube from lying flat against the rim which results in an uneven surface and is thus not a long-term solution.
If you happen to have some spare inner tube, you could try cutting a small piece, poking a hole to fit the Presta tube through and ensuring it’s wide enough to cover the base of the valve, thus acting as a shield.
Or if you’re really in a bind, you could try wrapping the valve in electrical tape.
Switching more permanently to a dual system is also a possibility. You can drill a Presta-size hole on the opposite side of your rim and use either a Presta or a Schrader tube.
It’s important to take caution in avoiding the welder’s seam in the rim, and be aware that this approach has the potential to reduce the integrity of the wheel. If you do go for a dual system, make sure to have a ‘boot,’ which can just be a piece of cardboard or plastic to cover the unused hole and help prevent the tube from blowing.
Ideally, you could simply purchase a grommet. Plastic, metal and rubber grommets are specifically designed to solve this problem. The piece keeps the Presta valve in place despite the wider opening and acts as a seal, keeping unwanted debris out of your wheel.
My bike takes Presta tubes so I have yet to encounter this problem personally. But there are many options out there to help you get by. I do recommend taking caution if you decide to drill a hole in your rim and make sure you know exactly what you are doing.
Personally, I would only use a Presta tube in a Schrader rim in an emergency situation, unless I had a grommet to help reduce the risk of the tube bursting. The last thing any cyclist wants is to be stuck with a flat.