John said:

My reply was predicated on that, so lets clarify:

IF there is a dished washer, it should be installed on the inside. MANY tubes do NOT come with a washer - in which case, no washer required. The tube manufacturer has their own way of making a tube and know what it needs, so whatever they supply should be used.

I certainly wouldn't go looking for a dished washer if the tube didn't come with it!

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

Been using tube tyres on dirt bikes for decades.

If the tube came with a washer .. then that washer and one nut should ALWAYS be attached to the tube .. inside the rim.

Now for the contensious issue.. what goes ontside the rim on the valve stem.
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The metal valve cap and the metal valve cap only. Forget the plactic caps - they will leak air pressure if the valve leaks.

Forget the nut ... it is used by lazy people when the tube has no air in it. If you do use it and the tube leaks you can rip the valve stem from the tube. With no nut the stem will be pulled into the rim, you will notice that and be alerted to the problem before terminal damage is done. A simple check to see it the valve stems point right at the wheel centre, if not then you have a problem.

--- So now you have another idea of what to do. Your choice of which one to take.




[This message has been edited by Frank Warner (edited 03 May 2004).]

Hi John, After messing about with tubes in tubeless tires on my R80RT with alloy wheels and having mixed results I went to a 90 degree valve stem on a tubeless rear wheel. It works very well and makes checking and filling the rear wheel much easier.
On the front I still run a tube in a tubeless tire. I put in the tube with one nut on the tube and the other finger tight on the rim.

In 100,000kms only one flat on the front and it is possible to repair on the road, although it is very difficult to reseal the bead properly.
Also one flat on the rear, wich is a very different story. The tube exploded in the tire, and was useless when removed. We had no spare so we reused the tubes valve stem and glue to seal the valve stem hole in the rim and plugged the hole in the tubeless tire. however we could not reseal the bead even with a co2 air cartridge. we had to take the whole wheel to a garage to reseal the bead on the rim.They also had trouble but finally got it. This repair lasted 400kms till I fixed it properly.
So now I run the front still with a tube cause I know I can fix it if it goes flat, and the back is tubeless because now "maybe" I can fix it if it goes flat...cheers, Peter

Hi, Frank & Cameron,
I must say that I'm not happy about having a nut between the tube and the rim. The tube, or the base of the valve stem, will nestle quite comfortably in the dished washer, but if the washer has the nut between it and the rim, then no way will the tube seat properly in the rim, it will be held away from it by this nut. As I said in my original question, the function of the nut can be performed equally well by having it on the outside of the rim. I must admit, though, that I don't know what sort of pressures you use on a dirt bike, perhaps if they are really low (10 lbs?) then the issue of the tube not seating snugly on the rim might not be such an issue. On the other hand, I don't suppose that with my old banger ('82 RS) with 70bhp (it might have been, a long time ago) tyre creep will be much of an issue either. If I'm going to look at the tyre or the valve stem, then I expect to have noticed that the tyre is flat (or is getting flat) long before it has got flat enough to have the tyre creep. Likewise, the tube with the nut on the outside is better able to remain intact while the forces are still in shear than it will be once it's been partly dragged into the rim and being restrained only by the valve cap.
Hell's bells, ain't this is a can of worms, we've all got our own ideas on the fitting of tubes, yet we all seem to have survived so far!
Cameron, I've just realised that I can't use the 90-degree adaptor if I've got tubes, or do they make inner tubes for bikes with a bend in the valve stem like I think they do for lorries? (You have trucks, we have LORRIES)
Many thanks,
John

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Johnefyn

[This message has been edited by John Roberts (edited 04 May 2004).]

Hi John, My 90 degree adapter is nice shiny chrome and stands out wonderfully from the rest of the grime covered bike, and you are right it is for tubeless only...However here in Canada we can buy plastic 90 degree adapters that screw onto the valve stem and will work on a tube, but I am not sure that they are "robust" enough for motorcycles...

my god, even the simple things in life are complicated!!!!!!!

The simpler things get the more difficult the choice?

I've had tube creep on a 175cc bike with around 16psi .. it is not the HP that count it is the torque .. after first gear and clutch slip! And you can get front tube creep too.
I've riddeen on flat tyres .. not much different to riding in sand.. and if your doing both at the same time! More modern tyres can have very stiff side walls that mask flat tyres were well.

The inner tube stem will stay put by the action of the air pressure.. there is not much else acting on it. If the tube has crept to the point where the tube cap is holding it from going into the rim .. well it is well pass the point where the the tube would have been ripped out of a stem fastened to the rim by the nut. I've seen people riding with no stem visable .. it had dissapeared inside the rim... with the cap!!!