# Presta valves prone to losing air pressure?



## revrnd (Aug 13, 2004)

My Trek Fuel EX 8 came w/ Presta valves (my 1st exposure to them). It seems that they won't hold pressure as well as the Schrader valves on my other bikes. I've had the tubes off & checked them in a tire tank, but couldn't find a leak. Pump them up & by the next day the front tire will have lost half of its pressure.

Is this typical?


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## taikuodo (Jul 3, 2006)

Not typical, you must have a really really small hole. Did you double check? Sometimes I find a nano-hole that I didn't find earlier.


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## D4ng3r (Jul 26, 2007)

they dont lose air that fast. maybe a bad seal somewhere. try another tube.


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## crazy4blues (Sep 10, 2006)

Actually, no. Presta valves are designed to to hold a lot more air than shraders (that's why all the roadies have 'em). As Taik' has mentioned, you might just have a tiny hole; there could also just be a split in one of the seams. 

Finally, please forgive me if you've already checked this, but make sure that the small threaded "head" is tightened snugly against the stem. You probably already know this, but I thought I'd throw it in there . . . Just trouble shooting . . .


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## emptybe_er (Jan 15, 2006)

Check the threaded "collar" on the valve-stem. If the "collar" was loose when you last rode or inflated your tire, the stem itself might have a tear in it. The hole/eyelet for the valve-stem is pretty sharp and it's possible the tube may have spun while you were riding or it may have torn during inflation. . . and please don't try patching the tube at the valve-stem - it's time to install a new tube.


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## shiggy (Dec 19, 1998)

emptybe_er said:


> Check the threaded "collar" on the valve-stem. If the "collar" was loose when you last rode or inflated your tire, the stem itself might have a tear in it. The hole/eyelet for the valve-stem is pretty sharp and it's possible the tube may have spun while you were riding or it may have torn during inflation. . . and please don't try patching the tube at the valve-stem - it's time to install a new tube.


If by "collar" you mean the nut that can be tightened against the rim, do not use it. Do not tighten it. Take it off the valve stem. It can actually cause valve damage if it is over tightened. The only reason to have one is to prevent the valve from pushing into the rim when inflating. But never snug it down.

I bet the OP is not closing the small nut at the end of the valve as suggested earlier.


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## Trevor_S (Jun 25, 2007)

All my Presta tubes loose pressure way quicker then my Schrader. Presta on my road bike, 10 psi a night, on the dozen or so tubes of different brands I have had in there (110 psi) 

Presta on my MTB, 5 - 10 psi a day, regardless of the tube type, 40 rear, 30 front on them. Schrader, 5 psi at most a week on my MTB.

So nothing like what you loose but still, they **** me  I drill the rims on the AM MTB to run Schrader but can't on my XC, as the rim is to small  Have no choice with the road bike, wheels are way to narrow


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## Mike T. (Dec 30, 2003)

revrnd said:


> Presta valves prone to losing air pressure? Is this typical?


Nope. My track bike hangs with 125psi in the tires. The tubes drop just 10psi every week.


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## f2f4 (Aug 10, 2007)

shiggy said:


> If by "collar" you mean the nut that can be tightened against the rim, do not use it. Do not tighten it. Take it off the valve stem. It can actually cause valve damage if it is over tightened. The only reason to have one is to prevent the valve from pushing into the rim when inflating. But never snug it down.
> 
> I bet the OP is not closing the small nut at the end of the valve as suggested earlier.


Holy crap, I learned something today... I think I'll go out and loosen mine now.

I always figured they were to help keep stuff from rotating...


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## Mike T. (Dec 30, 2003)

f2f4 said:


> I always figured they were to help keep stuff from rotating...


They can't. They can only PULL the valve away from the tube (not a nice thing!). They can only resist pushing the valve in. Big deal. I'm into my 5th decade of _not_ using them and never suffered because of it.


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## Walt Dizzy (Aug 18, 2003)

*Tube thickness?*



Trevor_S said:


> All my Presta tubes loose pressure way quicker then my Schrader. Presta on my road bike, 10 psi a night, on the dozen or so tubes of different brands I have had in there (110 psi)
> 
> Presta on my MTB, 5 - 10 psi a day, regardless of the tube type, 40 rear, 30 front on them. Schrader, 5 psi at most a week on my MTB.
> 
> So nothing like what you loose but still, they **** me  I drill the rims on the AM MTB to run Schrader but can't on my XC, as the rim is to small  Have no choice with the road bike, wheels are way to narrow


Is it possible that the presta valves are on thinner tubes? They tend to leak air faster. I've checked for leaks on punctured tubes. I've had micro-pin holes. But I've never found air leaking out of a presta valve.

Walt


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## skaplan86 (Oct 17, 2007)

I actually have a presta tube that does the same thing...

I pump it up to about 40 or even 45 (front tire) and in under a week of not riding, the bike is resting on the rim... i took the tube out pumped it up and held it under water and no bubbles anywhere (i had the entire tube submerged)... i don't quite get it because i can do 20 mile rides and not have problems, i just have to pump the tire before every ride (even on back to back days)... 

I definately make sure to ride with a spare tube and if I ever get really bored i might as well just change the tube... whats a tube, $4? Its just too much work to get my front tire off (no quick releases) to change the tube when it dont need it


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