Nuts on inner tubes

[nairb]

You would have thought that after many years of changing tyres and tubes I would not need to ask the question.....
In the pic below .......
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Does one nut stay inside the rim and the other outside.  I have done it like this for years, but doubt has crept in.
Last week, I put a brand-new tyre and tube + rim tape on a rear wheel.  Within 35 miles the inner tube failed for some reason.  Not at the valve but within 15 cm.  The tyre seems ok.  I was still running the tyre/tube in.
Ta
Nairb

[Trigger]

one inside and one out 

[AshimotoK0]

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[Bryanj]

I always put one in one out when i did them in dealers but i read more about the method in Ash's picture

[Oddjob]

Both out. The tube valve is tapered to match the taper in the rim. Presume 2 nuts for locking effect.

[Laverdaroo]

One in one out to lock it is the way I’ve always done it too. My XL used to chew inner tubes doing one in and one out so swapped to both out. No issues since….


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[AshimotoK0]

There are 2 nuts so that you lock them together and leave a small gap between rim and the 1st nut

[nairb]

One nut in, the other out has worked well for years.  Or has seemed too.  The only flat tyres have been due to nails/screws etc. 
I have seen other ways of securing the valve or using the two nuts.  Example below....
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I had not seen the alternative way or had it mentioned......
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The new setup that failed was on a 750 parallel twin with loads of torque, which used two tyre locks to keep the tyre in place.  Maybe they failed.  I dont know.
I will try the 2nd pic method and check that those tyre locks do actually grip and hold the tyre.

[Trigger]

The original fitting was a 5mm thin nut on the inside with a thumb nut with a recess as in picture.

Just had look at a new inner tube and the nuts are 4mm thick and a standard thin wall spanner is 4.5mm thick so, you would have to find a thinner spanner to lock the nuts together 


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[K2-K6]

Years ago, weren't the valve stem arranged with flange on inner end, push through small hole in tube, then secured with external washer with a nut there to hold that assembly tight  ? Making it std to have nut on inside of rim. Now they are all glued in situ to make that clamp redundant. 

The washer to generally stop the tube fretting against any poor areas inside the rim around that location on motorcycle tubes.

Anyway, I've never clamped the external nut tight whatever the arrangement as it will always indicate there's some movement by leaning the valve over that may need another look at it to find out what's going on inside. Bolted tight to rim, it'll pull the tube off the valve without any warning if it moves much.

I think the washer on them nowadays is dished so that some movement can take place without risk of compromise to tube straight away. Tgey are usually very smooth finish to not present any "cutting" edges to the tube material.

[Matt_Harrington]

Ken, I was wondering why there should be a gap between the rim and 1st nut.

[Trigger]

On a new tube the first nut is tight and the second nut is just threaded on. This indicates that one nut on the inside and one on the outside. Also on some new tubes the first nut has a blob of thread lock on the thread 


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[Seabeowner]

Always both out locked together. Both the wheels on my 500 on original tyres (although I have no proof they didn't both have a punctures in their 4000 miles) have both out.

[Seabeowner]

Ken, I was wondering why there should be a gap between the rim and 1st nut.

Always thought was that you could see if the tube is moving, the valve will tilt. Saves waiting until it tears itself apart.

[AshimotoK0]

A guy got this back from Michelin

I sent my questions, as written at the beginning of this post, by email to Michelin UK in Stoke-on-Trent. I received the following reply from Tony Charlton, Technical Manager at Michelin.

"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.

For off road inner tubes being used at low tyre pressures there is a possibility of tyre creep, and the inner tube could be pulled around slightly with the tyre. If the inner tube is bolted to the rim the valve can be ripped out. If the lock nuts are raised further towards the valve cap then inner tube has some leeway to move before this happens. Any movement is thus obvious as the valve stem will no longer be straight and pointing at the centre of the hub, but will be pulled round at an angle by the tyre and can then be seen and corrected."