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BBQ and blues!
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Discussion Starter · #1 ·
When I removed the pump from my tire recently I noticed a piece of brass fall on the ground. It was the little stem from the presta valve . . . the part you unscrew. It had just broken off. Now it's too short, broke even with the top of the valve.

Is this fairly common?
 

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scruffy nerf herder
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thats one thing about these, they are susceptible to more breakage as the valve ages, or if you put inferior pumps on them, they will often bend and eventually break. Sometimes it happens, such is cycling.

Luckily tubes are cheap.
 

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Devoid of all flim-flam
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In my thirty plus years of cycling on presta valved tubes and tires, I think I've broken about 10 presta valves. Yes it happens. But it happens seldom.
 

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it's much more common to break a standard schraeder valve. Eventually, either the valve core will get bent or the valve stem will get a gash from the edge of the rim.
 

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Observation.

Is this fairly common?
Very common with some people, very rare with others, so it seems to be an operator's problem. As far as I can tell, those who wiggle their pump heads off their valves will break lots of stems. Those who pull off their pump heads straight down towards the hub will break fewer stems.
 

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I've only had one presta valve snap off. Maybe I was careless removing the pump that time, maybe the age of the tube had something to do with it. (Had been on the bike a while). But in the last year I've had to replace several tubes because the valves started leaking or wouldn't allow more than a few pounds or air pressure before it'd start leaking back out.
 

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"I resemble that remark!"
And here I thought the stooge Curly was the originator of that remark :)

It occured to me that Presta stems break much more easily if you unscrew the little knurled lock nut all the way down. Just unscrewing it enough - about two finger twists - for the valve to work will make it much harder for the pump head to bend or break the stem.
 

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Kind of thing that happens when you are new, and then perhaps again on your first event day. After that, you wise up. There are some psychotically cheap and crappy tubes that it can happen to routinely just from normal use unless you are really careful. Same way with crappy pumps. Some of them just don't work very well and can damage the opened presta valve stem. Stay away from cheap tubes and pump. Learn to use your pumps properly, and you should be fine.
 

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BBQ and blues!
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Discussion Starter · #12 ·
wim said:
And here I thought the stooge Curly was the originator of that remark :)
Didn't know Curly said it first. He sure predates that fat lazy cat by decades!

wim said:
It occured to me that Presta stems break much more easily if you unscrew the little knurled lock nut all the way down. Just unscrewing it enough - about two finger twists - for the valve to work will make it much harder for the pump head to bend or break the stem.
This is interesting. To pump up the tire I unscrew the lock nut all the way out as far as it will go. I didn't know you could just unscrew it about two twists and it would still allow you to pump up the tire.

Great info! Thanks!

MB
 

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Arrogant roadie.....
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People who are new to prestas often back the nut all the way, then jam the pump head on too hard. This ends up bending the shaft, resulting (eventually) in it breaking.
 

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I think it is reasonably common, but something that most of us eventually learn to avoid with care. I mostly ran into that problem when using tubes with valve stems that were too long for my rims. Since I ran out of those, the ones I have been using with the normal length stem haven't been a problem for me.
 

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WIM--Great Tip

"Those who pull off their pump heads straight down towards the hub will break fewer stems."

I always did it the opposite way, put the stem on the bottom and pulled up. Your way is MUCH easier to get a straight pull. Thanks.
 

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Follow-up question. I broke the nut off the end of a presta valve. Is there any reason why I can't go ahead and ride with this tube? Its my understanding that with a presta valve, the air pressure itself holds the valve shut. The nut only serves to keep something from pushing the value in and letting out pressure. In my case, I put the plastic dust cover nut back to prevent an object from pushing the valve. Is it safe to ride?
 

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Its my understanding that with a presta valve, the air pressure itself holds the valve shut. The nut only serves to keep something from pushing the value in and letting out pressure.
Exactly right - no problem using that tube. Many riders who use valve extenders ride with an unsecured presta valve stem all the time.
 
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