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Presta valve question. ?

4K views 19 replies 16 participants last post by  Portly Throckmorton 
#1 ·
hey guys

have presta valves on my new bike , used to schrader. I hear different answers for if u need the nut that u tighten to the rim. Do i need these nuts ?

what do u guys do on your bikes with them ?

thanx for any help
 
#3 ·
I typically don't use the nut. If I get a flat on the trail and have to use a hand pump I will use the nut to prevent the stem from moving around and cutting the tube during inflation. If I use the nut, I keep it snug, not tight. If it is too tight, it can pull the tube up into the rim and cause a rip in the tube.
 
#8 ·
Another question about Presta Valves ??

Hi, Couldnt find an answer in the search, so I'll just ask here. Man, I am runnin into some real inconsistencies with Presta, never had issue with Schraeder. Ok, here is the questions/problems.

1) I have a Redline Urbis, presta valves, and I can fill the tires on that bike with my air compressor, and a screw on Schraeder type adapter. But I CANT fill it with a Lezyne pressure drive (presta only) hand pump. No go. Not even one stroke. Just pressurizes the air hose on the pump. WHY ?!?!

2) Have a Fat bike, and SAME pump (Lezyne pressure drive) will fill both of those tires no problem. But they run low pressure, so I bought a highly reccomended low pressure tire gauge (20psi) max. It needs the Schraeder type adapter. It will only get a reading off my rear tire. Not the front. Both the valves work properly, inflate properly, and look the same. But it will not take a reading from front tire.. Why ?!?!

Its just an air valve, but seriously, whats the deal ? A presta wont fill with a presta only pump made to accept only presta ? Yet same pump will fill other Presta's ? A presta that can be filled with a presta only pump, but not be measured for air quantity ?

Weird...any suggestions ?
 
#9 ·
Hi, Couldnt find an answer in the search, so I'll just ask here. Man, I am runnin into some real inconsistencies with Presta, never had issue with Schraeder. Ok, here is the questions/problems.

1) I have a Redline Urbis, presta valves, and I can fill the tires on that bike with my air compressor, and a screw on Schraeder type adapter. But I CANT fill it with a Lezyne pressure drive (presta only) hand pump. No go. Not even one stroke. Just pressurizes the air hose on the pump. WHY ?!?!

2) Have a Fat bike, and SAME pump (Lezyne pressure drive) will fill both of those tires no problem. But they run low pressure, so I bought a highly reccomended low pressure tire gauge (20psi) max. It needs the Schraeder type adapter. It will only get a reading off my rear tire. Not the front. Both the valves work properly, inflate properly, and look the same. But it will not take a reading from front tire.. Why ?!?!

Its just an air valve, but seriously, whats the deal ? A presta wont fill with a presta only pump made to accept only presta ? Yet same pump will fill other Presta's ? A presta that can be filled with a presta only pump, but not be measured for air quantity ?

Weird...any suggestions ?
It's dependent a lot on the make of the tube/presta valve. It's hit or miss using those schrader/presta adaptors.

Also check the valve core. Sometimes they don't seat right and because of that the tube/tire will not fill properly.

-S
 
#11 ·
The Lezyne head is a bit funky to put on and if not engaged properly, it won't depress the brass top of the presta....thus you get the situation you talked about. Play with it a bit when you're not jonesin for a ride to figure it out. Once you get it, it's easy.....but it sure is a PITA at first.
 
#13 ·
I also use the nut because it holds things in place for inflation. I also use UST tubeless rims/tires and the tubeless valve cores REQUIRE you to use a nut because it seals the valve stem to the rim. I have no choice there. But you can buy unthreaded presta tubes that don't even have a nut. I think they're primarily for deep v road rims that stabilize the valve stem well enough on their own.

As for problems with pumps, it happens.

I always push the brass nut and let a little air out before I put my pump head on. On presta valves, that thing can stick (especially so if you have sealant in there). I would imagine Schraeders can clog with sealant, too.

Occasionally my Blackburn pump insists on pushing air out of the Schraeder end instead of the presta end even when I have it attached to a presta valve. I have to fiddle with it some to get it to work.

I suspect you're having problems with your valve cores sticking. Push them in to de-stick them before using your pressure gauge or pump.
 
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