nut on a Presta valve - yes or no?

[simonineaston]

They seem pointless to me - if the tube's pumped up, the valve doesn't move; if you get a flat you stop and fix it, so I don't see the point of them - but have I over-looked something?

[mjr]

They are essential as part of the counterbalance of the rim strengthener in the join opposite the valve. Without it, the valve alone weighs less than the opposite side and your wheel will be unbalanced and inefficient, with energy wasted making its centre of mass orbit the hub.

[Mick F]

If you don't tighten the screw, the valve cap compresses the valve.

Any road up, putting 120psi in there needs all the sealing it can get.

[Stevek76]

I find them useful for getting a pump on when theres no or very low pressure in the inner tube.

Quite useful for tubeless also...

[kylecycler]

Just don't do what I did and use threadlock to stop them rattling (guess why not...).

[kylecycler]

I find them useful for getting a pump on when theres no or very low pressure in the inner tube.

They're pretty much essential for that, I find, or at least highly desirable, if it's a press-on, not screw-on, pump.

[thirdcrank]

I've used Michelin valves which weren't threaded to take a locknut. I found it wasn't easy to get started with a push on pump. On valves with the locknut, I got into the habit long ago of slackening them off a bit once the tyre was pumped up. I once had a puncture which deflated the tyre very quickly and the valve was ripped out of the tube by the locknut.

[Jdsk]

I find them useful for getting a pump on when theres no or very low pressure in the inner tube.

They're pretty much essential for that, I find, or at least highly desirable, if it's a press-on, not screw-on, pump.

Yes. I then slacken them off.

Jonathan

[cycleruk]

What's that ticking noise ? Oh' it's the valve rattling in the rim.

[robgul]

If you don't tighten the screw, the valve cap compresses the valve.

Any road up, putting 120psi in there needs all the sealing it can get.

The OP was talking about the collar screw on the valve stem - not the valve dustcap - you're right about the seal screw though, needs to be done up.

[robgul]

The racing geeks will tell you that they add weight to the bike (probably the same people that used to drill holes in everything back in the day!)

Have to say I agree that they do hold the valve in position to connect a up or CO2 - but don't do the ring up too tight

[slowster]

When I rode a 26" wheeled MTB I had Michelin inner tubes which did not have a thread on the valve stems. The Michelin inner tubes which I purchased more recently for my 29" MTB do have a thread and locking nut. I think that might be because wide MTB tyres are much more likely to creep/rotate on the rim when the brakes are applied. That happened to me when my 26" tyres were aging and needed to be replaced, and I found that an inner tube without a locking would be dragged around with the tyre and a leak/puncture would then occur at the base of the valve - a location where it was often impossible to properly patch the tube.

I suspect that might be what prompted Michelin to add the thread and locking nut to their MTB tubes. I think their inner tubes for narrow high pressure tyres still do not have a thread.

[tatanab]

If they are done up snugly then you need pliers to undo them if you get a flat tyre - flat i.e no pressure not soft. Not for me since I discovered this about 55 years ago. I have no problem fitting a pump at the roadside or track pump.. Thumb pressure through the tyre is enough to stop the valve retreating.

[kylecycler]

The Schwalbe inner tubes on my 26" and 27.5" inch wheeled bikes come with locknuts - Schraeder valves, not even Presta.

[Mick F]

If you don't tighten the screw, the valve cap compresses the valve.

Any road up, putting 120psi in there needs all the sealing it can get.

The OP was talking about the collar screw on the valve stem - not the valve dustcap - you're right about the seal screw though, needs to be done up.

Ah, that's different then!

The knurled ring isn't a nut?

Any road up, the knurled ring isn't required on my Ambrosio Excellence rims as the brass balance weight supports the valve beautifully.
https://ciclicorsa.com/shop/ambrosio-ex ... ncher-rim/