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Fitting inner tubes
Another dumb question that everyone else knows the answer to:
I've just fitted a new inner tube on my '82 alloy-wheeled airhead and I just can't remember where the two nuts go on the valve stem. I've changed 20-30 tyres & tubes by now but find myself completely flummoxed, dammit-I don't remember wondering about it before, even. So I've asked at one garage, two tyre depots and two bikers that change their own tyres, and only one tyre depot fitter agreed with me that both should go on the valve stem on the outside (i.e. on the hub side of the rim,) with the dished washer going between the tube and the rim. It seems to me that whatever the function of the nut nearest the tube, it can still perform that job when placed on the hub side of the rim, and also be locked by the other nut tightened down next to it. On the other hand, if I left one of the nuts on the tube side of the rim it would prevent the tube from seating into the well of the rim. So, you see, I'm confused. Hope I haven't got you folks confused too. Cheers, John. ------------------ Johnefyn |
Hi John,
i can remember disded washers ,double nuts but only just, i'd fit the tude without the dished washer and with only one nut on the outside off the rim as you said,...leave the nut slack bryan |
Hi Bryan, Thanks again, I've just realised it was you who replied to my query regarding g'box end plates just now, as well. Thanks, twice! John ------------------ Johnefyn |
imho...
ABSOLUTELY use the dished washer, very important to protect the base of the valve stem - which is rubber - from getting cut. One nut on the outside would be my preference, locking the valve to the rim snugly, and you could use the second nut against the valve cap, but I don't think it's important. Although according to Continental: "Valve nut (tube type) Only a fitting aid. Should be twisted against the valve cap after fitting the tyre." REF: http://www.conti-tyres.co.uk/contibike/tsafety.htm ------------------ Grant Johnson Seek, and ye shall find. ------------------------ One world, Two wheels. www.HorizonsUnlimited.com |
Hi, Grant,
Well, bugger me! It never ever ocurred to me to tighten one of the nuts against the valve cap! Still, can't argue with Mr.Continental, can we? Er, one small thing before I go-what's ...imho? Thanks, Grant John ------------------ Johnefyn |
imho = "in my humble opinion"
fwiw = "for what it's worth" ymmv = "your mileage may vary" All just added to the "Smilies legend" for future reference when posting. I'll add more as they come to mind. ------------------ Grant Johnson Seek, and ye shall find. ------------------------ One world, Two wheels. www.HorizonsUnlimited.com |
IMHO it’s not smart to twist the nut to the valve cap on a rim designed for tubeless tires. The hole in the rim for the valve is much bigger then the valve so you need some cover to keep the sand out.
Tighten it loosely with your fingers and remember to readjust it when you increase/decrease air-pressure. |
The '82's aren't tubeless despite being alloy rims (iirc).
Note that there are THREE types of holes used for valve stems. LARGE one on tubeless rims for an all-rubber stem. SMALL on tubeless rims for valve stems with threads, ala many BMW's. SMALL hole for tubetype. The two small holes seem to be the same size more or less, but the tubeless one has a flattened surface inside and out so the valve stem can seal properly. I would only twist the nut to the valve cap if there was also a nut to twist to the rim. (Back to the original question - what to do with two nuts) Except - On a pure dirt bike running very low pressures it's normal to leave the nut off so the stem can move - indicating that the tire is turning on the rim. BUT - DO NOT ride with no nut holding the valve stem to the rim on a street bike using TUBES. I have seen valve stems almost cut through by vibrating back and forth in the hole in the rim when not using a nut. Of course on a threaded tubeless stem you MUST use a nut. The nut (on tubetype) should be tightened lightly as Alibaba says. I give just a slight tweak with a wrench. On tubeless threaded stems I tighten it a little more, a good quarter turn. hth... ------------------ Grant Johnson Seek, and ye shall find. ------------------------ One world, Two wheels. www.HorizonsUnlimited.com |
Hi,AliBaba
I think you may have a point with what you said about keeping sand and stuff out of the valve hole. Have you had a look at the Continental website mentioned in Grant's reply, there's a lot in it but precious little regarding changing tyres. I don't know if what I've copied from their site is subject to copyright- it is in the interest of safety, after all (what do you think, Grant?) but here it is............ Fitting tyres Only specially trained persons should fit tyres. Fitting tyres requires that you lubricate both sides of the tyre bead and rim, all the way around. Use a commercial tyre-bead lubricant or soapy water. Do not use a petroleum-based or silicone-based lubricant. Observe the directional arrow on the sidewall. Do not use sealing liquids. Valve nut (tube type) Only a fitting aid. Should be twisted against the valve cap after fitting the tyre. With thanks to Continental tyres for the above excerpt. The impression I get is that they don't really want us to change our own tyres anyway. And, no, I must admit never having seen a valve cap lock-nutted, has anyone else? Many thanks, John ------------------ Johnefyn |
Hmm Conti’s page is creepy:
"Check inflation pressure, and adjust if necessary, on every refuelling stop" Well.... "Avoid impact strain (E.g. curbstones)" Sure I try to, but you know... "Continental does not recommend repairing a damaged tyre by simply fitting a new inner-tube. Due to safety reasons CONTINENTAL recommends to always fit a new tyre instead of repairing it. " Well they don't mention patching so I guess that's okay :-) When it comes to twisting the nut against the valve cap I always did it on my trial-bike to see if the tire moved but I will not do it on the BMW, maybe I had did it if I had rims designed for tubed tires. First of all there is no need, the tire never moves (even with extreme low air-pressure and hard driving) and I don’t want the sand to get into the hole. |
Hi, Ali
I can't qute see what you mean when you say that you screw the nut up to the cap to see if the tyre has moved, there's something I don't understand here, I think. (Though I do realise that that was only on your trials bike) As to Conti's suggestion regarding checking the pressures at every fuel stop, well, of course we all do that, I also try to change the oil and fiter too. As one does, naturally. Just you try and check the pressure on the '82 alloy rims- you lose half the air that's in them, and as for getting the inflator into position, that's a nightmare. I'm about to get some of the 90-degree alloy adaptors and have the wheels rebalanced- does anyone have any thoughts/experience on those? Cheers, John ------------------ Johnefyn |
If the wheel moves the tube will also move.
If the nut is not screwed towards the rim (screwed towards the cap, or in your pocket or somewhere else) the valve will not point directly to the center of the hub anymore if the wheel starts to move on the rim. This is a warningsignal and you can relocate the tube before the valve get ripped out of the tube, which is very hard to repair. If you screw the nut towards the rim it will not be that easy to see if the wheel starts to move and it will be less flexible and rip out the valve earlier then if you had mounted it without a nut. On my bike the wheel has never moved so I always screw the nut fingertight to the rim. I have some adapters made of rubber, they work great, alloy should be more robust. Another option is to bend the inflator so it fits…. |
Ali... Ah-I see what you mean, of course. Mind, as to what you say about bending inflators, the nice people at the filling stations won't like it... Digressing a bit, I see you're in Norway, I'm very fond of your country, and visited it five times in the seventies in my Bedford CA van with student friends, tell me- do they still have oiled gravel (honestly) roads with the lethal corrugations there? They were positively murderous on the hairpin bends in the fjords. You must have one of the most spectacular scenery in the world. Mind, it was horrendously expensive there then. Perhaps all this belongs elsewhwere- the Regional forums in the HUBB; I don't remember much mention made of Scandinavia at all there. Thanks again, J ------------------ Johnefyn |
Hi again,
the advice i posted is correct imho, uk mot road safety testers check the nut isn't tight,...as the valve stems shows if the tube has moved "in service",haynes manuals echo this advice(is that a good thing http://www.horizonsunlimited.com/ubb/wink.gif). i have metzeler,michelin tubes, dating back to early 1980's ,and a new conti tube(d21) 6weeks old,all are single nut/no dished washer. advice as always was posted in good faith |
Hi, everybody,
This is getting serious. All of the responses from you make sense, but they're all slightly different, surely we can't all be right. So what I'm going to do is ask some of the tyre manufacturers. I'll e-mail a few and see what they say about it. Let's see if even they can agree about the right way to do it! Thanks everyone, I'll be in touch. J ------------------ Johnefyn |
John said:
Quote:
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! ------------------ Grant Johnson Seek, and ye shall find. ------------------------ 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. ----------------------------------- 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 ------------------ 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...
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my god, even the simple things in life are complicated!!!!!!!
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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!!! |
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