It needs to be 8mm or 5/16" for Schrader or Woods valves. I've drilled a few rims and just file of any burrs.
What's so great about presta valves?
- Thread starter Dadam
- Start date
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It needs to be 8mm or 5/16" for Schrader or Woods valves. I've drilled a few rims and just file of any burrs.
OK, I bow to your experience. I was just going off what the internet said was the valve diameter, though I did see one page suggesting a 7mm hole.
Many years ago I watched as a friend of mine converted a rim from Presta to Schrader mid ride by boring out the valve hole using only a small Swiss army knife.
It was his only option as he punctured and we only had Schrader tubes as spares.
I was convinced it wouldn't work, but it only took a few minutes and looked pretty neat once done. Double walled rim too!
It was his only option as he punctured and we only had Schrader tubes as spares.
I was convinced it wouldn't work, but it only took a few minutes and looked pretty neat once done. Double walled rim too!
Simplex and Cyclo-BeneluxSachs-Huret is what you need.
The only problem I've had with Presta was when a valve core came loose and would occassionally let air out. I managed to finish the ride, but had to periodically pump the thing up.
Just yesterday I had a similar valve issue with my (very much Schrader) car tyre, so...
Just yesterday I had a similar valve issue with my (very much Schrader) car tyre, so...
Ajax Bay
Guru
- Location
- East Devon
Doesn't this 'Presta valve core coming loose' only happen when riders are using a screw-on chuck (as opposed to press on with lever)?
youngoldbloke
The older I get, the faster I used to be ...
Yes.
Wasn't using screw on... got no pumps with such a thing!
Ajax Bay
Guru
- Location
- East Devon
If not using a screw on (and off) chuck) any idea how (in what circumstances) you applied an unscrewing torque to the valve core (resulting in it coming loose)? What do you mean "occasionally"? Did the air come out in puffs? What action have you taken to mitigate this risk?
youngoldbloke
The older I get, the faster I used to be ...
A push-on chuck could loosen a Presta valve core if it's twisted a bit when being removed. Many posters are complaining about flying Presta cores disappearing as the pump is removed - a screw on adaptor is the perfect tool to undo them. I carry a little Presta core 'spanner' in case anyone I'm riding with is using loose-core tubes. I myself make a point buying only tubes with fixed Presta cores (and smooth valve barrels).
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Andy in Germany
Guru
- Location
- Freiburg im Breisgau
My intern pumped a tyre up to seven bar today, with a Woods/German valve. I've no idea why. I said he'd have to be very careful opening the collar. It's a moot point as he couldn't get it to turn under the pressure.
He like to poke fun at me for using Presta valves, so I pointed out that a Presta would be easy and safe to release.
He like to poke fun at me for using Presta valves, so I pointed out that a Presta would be easy and safe to release.
figbat
Slippery scientist
- Location
- South Oxfordshire, UK
I'm not sure how - the clamping force of a push-on pump head is on the valve barrel - there's nothing that grabs the valve core so even with twisting there should be no torque applied to the core. As for a valve core tool - one of the dust caps on one of my bikes has a built-in core tool (the item on the right).
In terms of benefits or favourites, all of my 'new' bikes (anything this century) have Presta and I get on OK with them. I did once bend a valve core but it bent back easily enough and continued to seal. The 20th century bikes are all on Schraders, the main issue I have being the depressing of the valve core to release air when deflated or rolling up a tube. My 1979 Dawes Kingpin arrived with Woods/Dunlop valves which was the first I'd ever seen of them, but I quite like them in a quaint, over-engineered but simplistic way.
In terms of pumping them all up, every bike-specific pump I have or have used has an interchangeable head.
youngoldbloke
The older I get, the faster I used to be ...
The thick rubber 'washer' in a push-on chuck can grip the core enough to loosen it if not well tight. I prefer pumps with screw-on adaptors (eg Lezyne) as it's all too easy to bend the valve core, especially with a push-on mini pump.
GuyBoden
Guru
- Location
- Warrington
Ajax Bay
Guru
- Location
- East Devon
Well get tubes without removable cores then. Totally un-needed unless you're trying to inject 'slime'/sealant.
