Bicycle Mechanics - Presta valve mystery

Ok, so last week I switched to presta valves on the advice of my LBS. This morning when I came downstairs rear wheel was completely flat! I pumped it up again and went about my business - cycled the 10 miles into work.

So my question is.......is this normal? Do presta's spontaneously deflate? Now my basemnent was probably pretty cold last night - would that have caused it?

Did you make sure that the knurled nut at the end of the valve was tightened down?

Originally posted by velocipedio
Did you make sure that the knurled nut at the end of the valve was tightened down? Actually, it does not have to be tightened down,but doing so prevents accidental discharge, in case it should get bumped.I have valve stem extensions, and leave the nut untightened,no problem.Mine are in an unheated garage.The 'advice' to switch sounds like some kind of applesauce.WHY?, if the Schraders were working....

Originally posted by pokey
Actually, it does not have to be tightened down,but doing so prevents accidental discharge, in case it should get bumped.
That's what I was thinking... that something may have inadvertently pressed the valve piston.

Originally posted by velocipedio

That's what I was thinking... that something may have inadvertently pressed the valve piston. Any 'rug rats' around?

Or maybe you just got a bad tube.

Cheers...Gary

So my question is.......is this normal? Do presta's spontaneously deflate? Now my basemnent was probably pretty cold last night - would that have caused it?

not normal. as the guys above have postulated...

Presta's - easier to pump up with a hand pump
Schraeder's - can pump up at the gas station

otherwise, there's not a whole lot of difference.

i have mostly prestas on my 4 bikes. the only problem i sometimes have is that the valve stem sometimes rips out of the tube a little too easily - i've done it while pumping before. maybe i just had some cheap tubes...

the low temperature shouldn't make THAT much of a difference and it will "reinflate" as you ride and warm the air in the tire a little or bring it inside.

Thanks for the replies

Schraders weren't working - I was getting lots of flats - then again this is not an auspicious start for the Presta's (less than 100 miles)

yes the little valve was tightened

there is a rug rat but she doesn't get into the basement

maybe it is a bad tube - I just checked the bike in my office and the tire is getting softer - must be a really slow puncture or something to get me 10 miles to work with no noticeable loss in pressure.....

anyhoo I have a spare tube in my bag - I guess I'll fix it before I leave the office and hope I don't get another flat on this freezing DC day

Originally posted by brennser
Thanks for the replies

Schraders weren't working - I was getting lots of flats - Prestas get lots of flats too.Best partial remedy is flat resistant tires.

Well seems I am the only one. I have owned 5 presta valve tubes and hate them all. They all popped around the valve WAYYY too easily. If you can't be a little rough then they are useless to me.

Originally posted by Maelstrom
Well seems I am the only one. I have owned 5 presta valve tubes and hate them all. They all popped around the valve WAYYY too easily. If you can't be a little rough then they are useless to me. That would suggest you are doing something wrong.No problem here.

a little OT but is it advisable to use presta valves on a schraeder drilled rim?

Originally posted by tFUnK
a little OT but is it advisable to use presta valves on a schraeder drilled rim? Usually no prob,,but there could be with really high pressure tires where the pressure could force the tube into the larger gap where the stem goes thru the rim,but there are gromets that make them fit better and fill the gap.

Originally posted by pokey
Prestas get lots of flats too.Best partial remedy is flat resistant tires.

Or Mr Tuffys, they are worth the investmant over 3 years not a single flat You do have to be careful with presta valves they are easy to snap then they don't hold air make sure when using a hand pump that you hold the valve securely with your hand

You have to screw down the nut on the end of a presta valve or it could leak slowly.......

Originally posted by pokey
That would suggest you are doing something wrong.No problem here.

Oh I know I was doing something wrong. I would pump using a hand pump (oh boy easier to pump but it sucks if you are in a rush which I always am). I would rather have a valve that doesn't break under human strength. I am not a gentle person and don't care to be for the sake of a valve. :)

If you can't be a little rough then they are useless to me.

Yeah, that was the problem with all of my Faberge eggs, so I dumped them.


I would rather have a valve that doesn't break under human strength. I am not a gentle person and don't care to be for the sake of a valve.

Aside from the somewhat unreal sense of that comment, it is very easy to break a valve of any kind if you do not keep the valve from moving a lot at the rim. Usually holding the pump head, valve, and rim together will suffice.

OTOH, you might be able to find a stainless steel tube somewhere.

Cheers...Gary

Presta valves are as tough as Schraeder valves, but they are different and require a different technique when handling them. If you insist on trying to 'beat them into submission' they aren't going to work for you.

Originally posted by pokey
Usually no prob,,but there could be with really high pressure tires where the pressure could force the tube into the larger gap where the stem goes thru the rim,but there are gromets that make them fit better and fill the gap.
This is one of my more common tube failures even w/my rims drilled for prestas. Presta pump heads generally fit pretty snugly, and it's easy to damage the stem/tube right at the hole while removing the pump head.

You don't need to screw the knurled bit down as the pressure should keep the valve closed (the valve could be defective however, and it does prevent accidental deflation).

The comment that you had a lot of punctures with Schraeders and now have with Prestas suggests either you are installing incorrectly or that maybe your rim tape isn't right.

i've used Prestas for about 25 years and no real puncture problems, other than occasionally them letting go at the valve to tube junction if overpressurized.

Originally posted by gmason


Yeah, that was the problem with all of my Faberge eggs, so I dumped them.



Aside from the somewhat unreal sense of that comment, it is very easy to break a valve of any kind if you do not keep the valve from moving a lot at the rim. Usually holding the pump head, valve, and rim together will suffice.

OTOH, you might be able to find a stainless steel tube somewhere.

Cheers...Gary

I don't get the first comment.

As for the second. I don't agree. I have been commuting for a long time and have never broken regular valve (and until this year have never owned a floor pump). I bought my current mtb in the spring and it came with these presta valves. Cool, something new. (not new but new to me) two bikes, 4 wheels, 4 pops all with a handpump in a matter of 2 weeks.

So there are two option. 1 - Did my bke come with the worst presta valves on the planet causing mine and my cousins (I didn't do these ones but he broke 2 as well) to break under what I consider 'normal' pumping action.? Or do presta valves blow...hmmmm...

I agree with Davet presta and schraders are about the same strength wise. when I had schraders I used to carry spare cores for when I broke one, I guess that is one advantage to them you can replace the core without replacing the tube. Prestas on the other hand are easier to control the amount of air pressure. You really should never use a gas station pump to fill your tire it is to easy to blow them up, if you do be careful. And pick up an adapter from you LBS they are usually under a buck and they come in very handy. And Maelstrom remember technique and finesse can be better than brute force :D

Just this dudes $.02 worth