Author Topic: Inner tube valve lock nuts  (Read 281 times)

Offline Grunt

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Inner tube valve lock nuts
« on: March 23, 2018, 08:59:08 AM »
Iíve just got round to fitting the tyres and tubes to my Bonnie wheels.

The tubes (Michelin) come with two nuts and a dished washer on the valve stem. To me it seemed obvious that the washer is fitted on the valve stem between the tube and the rim, with the nuts fitted on the outside of the rim to stop the stem pushing back into the rim.

The tube I took off which was fitted way back when I walked briskly and could run up stairs had one lock nut tightened down onto the the washer on the inside of the rim. This was probably fitted professionally.

Having got the front wheel sorted I wondered why two nuts were supplied. So I did an inter web search. The inter web being what it is offered more permutations than Vernons.

The conclusion I have come to is that I have fitted the tube as the manufacturers intended, with only the washer (fitted dished side towards the tube) on the inside. And the two nuts on the outside not tightened down to the rim but locked together mid way up the valve stem, which will allow the stem and tube to flex on the rim without damage, and also to indicate any tyre or tube creep by an angled stem.

So if you still there and havenít nodded off after all that waffle whatís anyone elseís opinion.
« Last Edit: March 23, 2018, 09:01:13 AM by Grunt »

Offline Rex

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Re: Inner tube valve lock nuts
« Reply #1 on: March 23, 2018, 09:57:23 AM »
Definitely NOT as you've done it! You're relying on the tube/valve area being a snug fit in the well of the rim to apply pressure to keep the valve stem in place. I've always (ever since the days of push-bikes) run one nut down onto the dished washer and put the other nut on the outside of the rim.
Some these days (bizarrely in my view) leave the outside locknut up near the valve cap. What does that achieve? :-\

Offline iansoady

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Re: Inner tube valve lock nuts
« Reply #2 on: March 23, 2018, 10:03:56 AM »
That was always recommended by Sam Miller (amongst others) as the valve stem will tilt if the tyre starts to creep on the rim rather than ripping it out. Admittedly he was talking about trials tyres at 4 psi but I think the theory holds.

If you think about it, what purpose do the nuts actually serve if they're tightened down?
Ian
1952 Norton ES2
1982 Moto Guzzi V50

Offline Grunt

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Re: Inner tube valve lock nuts
« Reply #3 on: March 23, 2018, 01:15:44 PM »
I checked the fit of the tube and valve with the washer and nut and just the washer before fitting the tyre. The tube looked the most comfortable when fitted with just the washer.

I donít see the point of clamping the tube to the rim with the nuts. If your relying on them to stop movement of the tube then surely you should be fitting tyre clamps.

I have tubes fitted to my landrover the valve stems on these are rubber and apart from size they are identical to tubeless valves made of rubber with no thread. And no means of clamping the tube to the rim even though they are off road tyres and run at low pressure.

From what Iíve gleaned from the internet. Some use one of the nuts as a locknut against the valve dust cap. If you are in the one nut inside and one out, but not clamping the valve to the rim camp, then the outside nut has to go somewhere and I suppose backing it up to the dust cap is as good a place as any.

Any how Iíve emailed Michelin to see what they say. We might as well get it from the horses mouth.
« Last Edit: March 23, 2018, 01:17:24 PM by Grunt »

Offline Grunt

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Re: Inner tube valve lock nuts
« Reply #4 on: March 23, 2018, 04:26:43 PM »
Iíve got a reply from Michelin.

Quote
Thanks for choosing Michelin inner tubes for your bike.
 
The inner tube is installed  with the conical washer sitting between the inner tube and wheel rim.  On a road bike the first lock nut should then be run down to lightly touch the rim, and then backed off by half a turn.   The second lock nut is run down until it meets the first one, then the two nuts should be locked together by using spanners to rotate them in opposite directions.
 
I hope that this helps,
 
Best regards,
 
Tony Charlton
2w Customer Engineering Support Ė Operational Marketing

So there you go my intuition came up trumps for once. I fully expected to have to take the tyre off and start again.

Offline Rex

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Re: Inner tube valve lock nuts
« Reply #5 on: March 23, 2018, 07:29:32 PM »
Blimey, there must be many bikes (including mine) with the valve nuts wrongly installed then... ;)