# Schrader Valve Head Sizes



## armstrong (Jul 9, 2013)

Hi folks

I was wondering if the "head" of the valve - the thing you grasp and screw to close or open - have they changed sizes in the last few years? I have a floor pump that I bought about 20 years ago. It seems I'm having a hard time fitting some Schrader heads into the head part of the pump. They are just too big. I've managed to jam them in to make them work, but some of my bike tubes also seem to fit in quite easily (like they did 20 years ago when I bought my pump). Anyways - it got to the point where I got a pen and opened up the hole of the pump larger, and now it seems to not be making a seal anymore. So what's going on? Is there two sizes for these Schrader valve heads?


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## Kerry Irons (Feb 25, 2002)

armstrong said:


> Hi folks
> 
> I was wondering if the "head" of the valve - the thing you grasp and screw to close or open - have they changed sizes in the last few years? I have a floor pump that I bought about 20 years ago. It seems I'm having a hard time fitting some Schrader heads into the head part of the pump. They are just too big. I've managed to jam them in to make them work, but some of my bike tubes also seem to fit in quite easily (like they did 20 years ago when I bought my pump). Anyways - it got to the point where I got a pen and opened up the hole of the pump larger, and now it seems to not be making a seal anymore. So what's going on? Is there two sizes for these Schrader valve heads?


No change in size - it's an international standard. It's possible that some Schrader valve stems have a thicker coat of rubber on them and maybe that is what is preventing your pump from going all the way on, but it is not the diameter of the threaded section. The Schrader valve was patented in 1893 and has not changed in size.


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## wim (Feb 28, 2005)

armstrong said:


> I was wondering if the "head" of the valve - the thing you grasp and screw to close or open - have they changed sizes in the last few years?


You're sure you're talking about Schrader valves here?


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## PJ352 (Dec 5, 2007)

This may help clarify things:

Presta vs Schrader valves by Jobst Brandt


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## JCavilia (Sep 12, 2005)

> the "head" of the valve - the thing you grasp and screw to close or open


I don't know what you mean here, and this prompts me to repeat wim's question: are you talking about Schrader, or Presta. You don't unscrew anything (except the cap) to open a Schrader valve.

In any event, I suspect your 20-year old pump had a mangled gasket that was interfering. Your operation with the pen has probably destroyed the gasket now (hence the lack of seal). You need to replace the gasket (if available) or get a new pump head.

But I'm still curious what kind of valve you're talking about.


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## armstrong (Jul 9, 2013)

Presta. Oops. My bad. Shows you how long I've been out.

I'm talking about the valve-thing that you grasp between fingers that opens and closes the tube. I have some tubes whose valve-thing is bigger than others, and some that are quite small and fit easily into the head of the pump.


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## JCavilia (Sep 12, 2005)

armstrong said:


> Presta. Oops. My bad. Shows you how long I've been out.
> 
> I'm talking about the valve-thing that you grasp between fingers that opens and closes the tube. I have some tubes whose valve-thing is bigger than others, and some that are quite small and fit easily into the head of the pump.


The thing is called a "nut" or "captive nut" or "valve body nut" (not to be confused with the valve-stem nut that some Presta tubes have), and it's always smaller in diameter than the valve stem onto which the pump head gasket grabs, so it should not interfere unless the pump is messed up. Which it sounds like yours is, at least now.


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## armstrong (Jul 9, 2013)

I'll go home and take photos of the different size "nuts" that seem to appear on tubes I have. Some fit in and get pumped easily, others don't; they have to be jammed into the head of the pump in order to fit.


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## tlg (May 11, 2011)

armstrong said:


> I'm talking about the valve-thing that you grasp between fingers that opens and closes the tube. I have some tubes whose valve-thing is bigger than others, and some that are quite small and fit easily into the head of the pump.


The "valve-thing" *A* is bigger than *B* and *C* ?


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