Presta valves

General cycling advice ( NOT technical ! )
David2504
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Joined: 11 Mar 2021, 5:29pm

Presta valves

Post by David2504 »

Hi, on a ride today I had a problem with presta valves when repairing a puncture. Basically after fitting a new tube and inflating, the core came out with the pump. This happened a couple of times. It’s the first time I’ve experienced this problem. Any tips for avoiding?

For example a tube with a non-removable core. Michelin do one called the Airstop. They seem to be in two possible sizes for my tyres 18-25 and 25-32. If I go down this route would I be best with the narrower or wider tube for 25mm tyres? In reviews my tyres which are Conties have been measured at 25.6mm.
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531colin
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Re: Presta valves

Post by 531colin »

Errrr...make sure the removable valve core is screwed in reasonably tight?
The actual width of a nominal 25mm tyre varies depending on the rim. As to which of the tubes would be "better" , I would base any decision on which tube looked the better size when I had the tyre and both tubes to look at.
Other opinions are available....some folk always go for the smaller tube, because they reckon they are less likely to pinch it when fitting, some folk always go for the bigger tube as it will be less stretched therefore thicker when inflated.
David2504
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Re: Presta valves

Post by David2504 »

Hi Colin thanks for reply

Yes, obviously ensuring core is properly tightened is the thing to do. Thing is I tried three ‘out of the box’ tubes. Two of which I was carrying and a friends. The same thing happened on all three. Eventually we got it sorted, but as you can imagine it caused a bit of angst, not to mention time, Obviously doing this on the side of the road 20 miles from home is more stressful than doing the same thing at home.

I just wondered whether carrying a tube with a non-removable core might be a sensible thing to do on a ride. Those tubes tend to be cheaper whether that is reflected in overall quality I wouldn’t know. When home it would always be possible to switch the tube, or even repair the punctured tube, refit it and put the non-removable core valve back in the saddlebag ready for next ride.

Just looking for a bit of advice from more experienced cyclists. :D
Last edited by David2504 on 1 Apr 2021, 9:13am, edited 1 time in total.
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: Presta valves

Post by Jdsk »

What sort of pump, hose and connector are you using?

Previous discussion:
https://forum.cyclinguk.org/viewtopic.php?f=5&t=118170&hilit=presta+unscrew

Jonathan
David2504
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Re: Presta valves

Post by David2504 »

Hi Jonathon, the first attempt involved a screw on CO2 inflator. I wondered whether the high pressure had caused the problem so the second and third attempt used a lezyne screw on mini pump. Obviously pressure achieved was lower but tyre seemed sufficiently inflated for limping home. The lezyne pump was a screw on type too, and I think that might be a contributing factor. However having said that, I’ve never experienced this problem before using the same equipment.
gregoryoftours
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Re: Presta valves

Post by gregoryoftours »

I suppose you could always remove and refit the valve core with some thread locking compound ahead of time, obviously being careful where it goes
markjohnobrien
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Re: Presta valves

Post by markjohnobrien »

While I’ve never had this problem of the core coming out, I loathe presta valves as the cores get wonky/bent and mess up the pumping of tyres. Much prefer schrader.
Raleigh Randonneur 708 (Magura hydraulic brakes); Blue Raleigh Randonneur 708 dynamo; Pearson Compass 631 tourer; Dawes One Down 631 dynamo winter bike;Raleigh Travelogue 708 tourer dynamo; Kona Sutra; Trek 920 disc Sram Force.
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mjr
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Re: Presta valves

Post by mjr »

markjohnobrien wrote:While I’ve never had this problem of the core coming out, I loathe presta valves as the cores get wonky/bent and mess up the pumping of tyres. Much prefer schrader.

Different rim hole required. Woods are better than schrader.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.
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kylecycler
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Re: Presta valves

Post by kylecycler »

Newer Lezyne pumps have a pressure release button - the black button in the photo - which you press before you unscrew the pump hose. It's to prevent you unscrewing the valve core as you unscrew the hose. Don't know if yours will have one, mine has and I got it about three years ago. IME not everyone who has one knows what the button is for or how to use it, though - I've got a pal who didn't. I think I read about it in the review before I bought it, otherwise I wouldn't have known about the problem of unscrewing valve cores and probably found out the hard way! You're still best to hold the valve between thumb and forefinger as you unscrew the hose and make sure it doesn't turn with the hose.

Image
Last edited by kylecycler on 1 Apr 2021, 10:54am, edited 4 times in total.
LollyKat
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Re: Presta valves

Post by LollyKat »

I was using a push-on pump when this first happened to me but fortunately I was at home. Now I make sure to tighten all cores before I fit a new tube, and keep a small core tool in my puncture kits.
brianleach
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Re: Presta valves

Post by brianleach »

Happened to me recently as well. Not an issue as I always carry a plastic valve tightener in my tool kit as well. Very small and weighs nothing at all.
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mjr
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Re: Presta valves

Post by mjr »

brianleach wrote:Happened to me recently as well. Not an issue as I always carry a plastic valve tightener in my tool kit as well. Very small and weighs nothing at all.

A small adjustable spanner or spoke key will also do the task.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.
Marcus Aurelius
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Re: Presta valves

Post by Marcus Aurelius »

Use a spoke key, or one of these.

https://www.wiggle.co.uk/tufo-valve-key

All tubes come with relatively loosely fitted cores in my experience. Give them a tweak before you screw the pump on, and they should stay put. Alternatively get a press on mini pump, or gas inflator.
Marcus Aurelius
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Re: Presta valves

Post by Marcus Aurelius »

gregoryoftours wrote:I suppose you could always remove and refit the valve core with some thread locking compound ahead of time, obviously being careful where it goes


You have to be very careful, doing this, as you’ll instantly gum the valve up if you’re not careful.
brianleach
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Re: Presta valves

Post by brianleach »

Use a spoke key, or one of these


Yep. That's what I carry.
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