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I have bikes with two types of valves: Presta and Schrader. Usually when buying bikes or rims, I'm very careful to buy only Presta stuff. If I for some reason end up with a Schrader rim, I may go even as far as use a rubber grommet and a special Presta valve locknut that has one side designed to be used on Presta rims and another side designed to be used on Schrader rims with excessive rim hole size, perfectly centering the Presta valve on a Schrader rim.

However, since buying a Brompton that originally had Schrader tubes, I found easily available Schrader replacement tubes and bought several of these, thinking that I'll convert my Presta mini pump into a Schrader mini pump by reversing some parts inside it. Then I bought a Presta-to-Schrader adapter that I decided to use should I get a flat on a Presta bike, using the mini pump in Schrader configuration.

Is this decision to use a Presta-to-Schrader adapter and a Schrader mini pump a good idea? What could possibly go wrong?

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4 Answers 4

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I think it’s a very bad idea to use adapters, especially in the repair kit that is used on the road side. Adapters can be lost.

Even mini pumps can support the two kind of valves directly. That is for me the best option if you have bikes with the two kinds of valve.

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    Adapters aren’t much smaller than the valve on a co2 cartridge and we’ve been keeping track of those in our tool kits for years.
    – jqning
    Commented Jul 8, 2023 at 4:08
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    The adapter can be installed on the pump or even on the tube valves and are less likely to become lost then. I used a universal shock pump with this adapter for some time on my bike when I lived in the UK (I also used it for Schraders on my Skike).
    – Vladimir F Героям слава
    Commented Jul 19, 2023 at 9:11
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Those who ride more-than-one bike might have different valve types between bikes.

My solution is that every regularly ridden bike has a toolkit on it, with 1/2/3 spare tubes to suit its wheels and a pump to suit those valves.

Regardless of what valve a bike has, I will always carry a cheap presta-schrader thread-on adapter in the toolkit too. They're small and light, and have been helpful multiple times. However I would not loose flexibility by making the pump do one or the other only.

Related anecdote - I swapped my toolkit between both recumbents for a while, given they both had 20" and 26" wheels of similar widths. However I didn't consider the pump was schrader-only and ended up doing a 2 hour walk to work, when the pump wouldn't attach. I couldn't even use a Service Station air bowser, hence the addition of the adapter to every toolkit.

So make sure your pump on that bike fits the valves and never worry about it again.

Or make an effort to standardise on one type of valve across your fleet - Presta everywhere works if you use inserts on the valve hole, or Schrader everywhere if you're prepared to modify the presta-sized holes on the rim.

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    Every bike I have has its own mini pump. That is the only way to not realize one forgot a pump when the crap hits the fan.
    – Vladimir F Героям слава
    Commented Jul 19, 2023 at 9:15
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No, the decision is a horrible idea. I failed to consider one peculiar feature of many modern Presta tubes, they have a removable valve core.

After getting a pinch flat, and repairing it, and pumping the tube to a high pressure, I removed the pump and proceeded to remove the Presta-to-Schrader adapter. It removed the entire valve core with it, immediately deflating the tube.

The second time I decided to tighten the Presta valve core really tight with a small adjustable wrench I fortunately happen to carry around always, and put the adapter on it really loose. After pumping again to full pressure, and removing the adapter, it again removed the entire valve core with it.

The third time I took apart the mini pump with roadside tools, reversed some parts inside it for Presta operation and had to pump up the tube a third time.

On Presta tubes without removable valve cores, Presta-to-Schrader adapters may work. However, removable valve cores usually are not very tight because you tighten against a rubber grommet, so there's a huge risk that when unscrewing the Presta-to-Schrader adapter, you unscrew the entire valve core along with it.

After thinking about this valve core removal incident that happened twice, I think I have an explanation. If tightening a valve core on a deflated tube really tight, and pumping up the tube to very high pressure, the pressure inside the tube acts to push the valve core away from the rubber grommet. Thus, the pressure makes it more likely that the valve core self-unscrews along with the Presta-to-Schrader adapter. So even if the Presta-to-Schrader adapter works perfectly on a deflated tube, it may fail to work on a tube with full pressure on it.

A possible solution to this problem might be to put the spare tube inside a tire and rim, inflate to full pressure, tighten the valve core really tight when the tube has pressure, then deflate and remove the tube to be used as a spare. However, this means a lot of work for every spare tube: it's impossible to use a tube bought freshly from a store, because it's mandatory to tighten the valve core really tight on a tube having full pressure in it. A lot of work for every new spare tube. And I'm still uncertain whether this will work, because testing it roadside would have been impossible.

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    Screwing out valve cores is a common issue with mini pumps with a detachable hose. You prevent it by letting out pressure from the hose first. And more importantly, by using medium strength thread locker on the valve core to valve stem threads.
    – gschenk
    Commented Jul 6, 2023 at 19:18
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    @gschenk You prevent it by letting out pressure from the hose first I wish. ;-) But Loctite Blue does work. I have 50 mm Conti tubes in my road repair kit because 50 mm will work with all my wheelsets, but the Contis do have the removable core.
    – Andrew Henle
    Commented Jul 6, 2023 at 19:37
  • A possible solution to this problem might be to put the spare tube inside a tire and rim, inflate to full pressure, tighten the valve core really tight when the tube has pressure, then deflate and remove the tube to be used as a spare. If you do that, and tighten the core with a wrench, make sure you prevent the stem from twisting by holding it firm with a pair of pliers or similar while you tighten the valve core. Otherwise you risk tearing the tube when you torque down the valve core.
    – Andrew Henle
    Commented Jul 6, 2023 at 19:39
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This may depend on the adapter but in my case the manometer on the pump was not working properly so no.

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    That seems like more of a pump problem than an adapter problem. Wouldn't it be a problem if used without an adapter?
    – DavidW
    Commented Jul 7, 2023 at 12:59
  • My pump is made for Schrader valve, and the manometer constantly shows correct pressure when the pump is connected to the tire with this valve. I can screw on adapter for Dunlop or Presta, but with this adapter, the valve does not longer disengage when the pump is attached, giving zero reading at still stand. It still moves during the stroke of the pump but then it is constantly in motion and I find difficult to judge what is exactly the pressure.
    – nightrider
    Commented Jul 7, 2023 at 13:16

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