Spoke wheel tubeless conversion on YAMAHA XTZ660 TENERE

updated late December 2008 - summary bottom of the page

Along with the RotW I have decided that running tubeless tyres (with no tubes) is a Good Thing. Having run them on my desert cars these last few years, the ease of quickly plugging punctures is an Even Better Thing, even if this practice is widely condemned as a 'get you home' measure and even outlawed in some countries. If tubeless fails in some way you can always slap in a tube and if you can't do that you just work something out.

To me running tubeless presents major advantages for overlanding. No need to carry tubes or even tyre levers. If you can't do a DIY repair chances are your tyre is well and truly buggered. I've had trips where I've crossed borders on flat tyres for want of an unobtainable tube. Now all I need is a pump and a handful of plugs, widely used in the undeveloped world: the home of AM-ing.

My new bike has spoked rims and tubed tyres so I asked on Horizons if gluing up the well of the rim (where the spokes come through and where air would probably leak out) was a good idea. The interesting discussion concluded it was do-able and had been done. So I did it too.

As we all know proper tubeless rims are solid (not wire spoked) and have a lip (mentioned in AMH on p65, see right) to sit the bead of the tyre securely on the rim's edge. It's a safety feature that stops the tyre coming off the rim when it deflates but in turn makes removing and mounting without bead breaking tools quite tricky.
As it happens XTs have long had such rims even though the bikes always come with tubed tyres. (Out of interest, this disproves the old yarn that you can only stick a tube in a TL rim to 'get you home' because it will eventually rub on that lip and burst with terrible consequences. Well clearly not on an OE tubed Tenere, lipped on the rear since the mid-80s AFAIK).
To convert the spoked rims to tubeless this lip is actually another good thing and my new Tenere had them on the back wheel. The front rim was normal which might be a safety issue when running tubeless, But can it be any worse than a tubed tyre puncturing? The word is tubed tyres deflate faster - and so more dangerously - than tubeless tyres so even without the safety lips on the front with tubeless I'm already ahead.

Sealing spoked rims

Gadgets like the Tubliss liner exist for low psi-running dirt bikes. I'd have liked to have tried it on one wheel at least, but they were not yet available in the UK in time for my Morocco trip so I took the cheaper option: gluing up the well of the rim' with a Marine-grade adhesive sealant called '3M 5200' (right). It's like the stuff you put round a bath edge but costs £15 a tube from boat shops and presumably last a whole lot longer in rough conditions.
My rims were in fairly good shape being only 700 miles old and once the near-new Tourances were removed (tried everything except the sidestand trick but had to go to a bike shop in the end) I dried out any moisture with a hair dryer, cleaned them with petrol and smeared the sealant all along the well. The 5200 version I used was FC: 'Fast Cure' so set in a few hours. I used half the 300 mil for both rims. Unfortunately the 5200 tube does not work with a B&Q sealant gun so I found it easiest to just cut the tube in half and paste it on with a knife. I tried to not leave any air gaps, small holes or get any on the rim edges where the tyre sits so as to keep the seal good. I fitted the rim tape back on for added protection and sealage.

Tubeless valves

Matey at my LBS who took the Metz's off flogged me some tubeless car valves but after hanging off the rim trying to pull them through I realised the holes on some tubeless rims, car or bike, must be bigger; 15 mm diametre? A tubed rim hole for a Schrader inner tube valve stem is about 8-9mm. I started drilling but before I'd gone too far I got on the web and yes, there are two sizes as well as screw in, two-part tubeless valves from about a fiver (see above, a good selection here - half ebay prices). By chance my local tyre shop had a pair (bartered down to 12 quid from a ridiculous £30!) which screwed in with a lock nut from the inside around two rubber seals (below right).

I had a pair of new tubeless Conti TKC80s (tubeless tyres have a better/stronger inner construction that tubed, I believe) and they levered onto the rims with a pleasing lack of drama. This was much eased by the fact that you don't have to worry about pinching the darned tube and instead are able to concentrate on scratching your nice black rims. I did make some rim savers out of hose (top right) but found they got in the way and could have ended up in the tyre (did that with a lever once in the desert. Took me ages to work it out!)

Mounting the tyres

This I knew would be the tricky bit. With no inner tube to inflate and push the tyre out onto the rim it could take some time and knackery before the air pressure got the bead to 'catch and seal ' on the lip and so pop it onto the rim.

It helped that I'd taught myself to do this on my old Land Cruiser's 16" rims, learning of bead-sealing techniques like clamping down the tyre with a tie-down, resting the tyre on another rim or anything round to get the lower bead to sit and seal on the rim under the tyre's weight while putting a soapy inflated 16" bicycle tube round the top to help make a seal (worked great). There was even the 'Icelandic Eruption' trick; squirting fuel into the tyre via the valve body (valve core removed) and lighting it in the hope that the small explosion inside would blast the tyre out onto the rim's edges. What also helped was having a decent 2.5 cfm Viair compressor attached to my car. It makes me think that a decent pump on the overland is an important accessory.

To cut a long story short it all took a day. At one point I looked for answers and ideas on the web. Tex in youtube made it look effortless with a sports bike tyre and a handpump! But for me even the 'Icelandic' (kit, left) did not work, or I didn't have the guts to use enough fuel; the tie-down clamp (top left) helped, soap and water did not do much, running a bit of soft hose around the edge of the tyre to try and seal the escaping air (as the bicycle tube trick did so well on the Toyota) did not work either.
In the end it was just a matter of technique: clamping the metal clamp of the tie-down right over the part of the tyre that was not mounted (so forcing the gap onto the rim), as well as manhandling the tyre, sitting on it, pushing and kicking it got the lipless front tyre on. If you don't have a chunky tie-down on the road, any rope or tape twisted tight with a stick will do to crush the tyre on.

Emboldened by this small victory after half-a-day's pissing about I eventually got the back one on too. The knack here may have been turning the car engine on to give my compressor that extra bit of poke to ram in the air in faster than it could escape out the sides. Important: take the valve core out to get the air in faster; once the tyre is seated it won't come off again, even with zero psi. Once the bead 'catches' you're on your way and you'll hear the long-awaited creak of a tubeless tyre easing over the lip and onto a rim with that satisfying pop. Now screw the valve core back in and pump back up to normal pressure. I've also added half a bottle of Slime (right) as a safety measure. Doesn't always work I found on my car, but still a good idea.

With no air loss over a few days I'm off to Morocco as planned, but with a front tube just in case the 5200 unpeels over the weeks. It's all an experiment for the moment so don't rush off and copy me just yet. I'd still like to try the Tubliss liner on the front if I get a chance and i may well be changing my back rim to an 18" when I get back anyway.

More news on how it all went - including running low pressures on the dirt - when I get back in a month.

Summary after 4000 miles in Morocco

For what they are the TKCs are great road tyres, you forget they're knobbly and on the dirt they manage fine, even at the road pressures I kept them at. I'd use them again. I also forgot I was running on experimental tubeless and should have been monitoring the pressure more regularly. Winding around off piste on the way down to Erg Chebbi I did think, heck these shallow, hard tyres are gripping unusually well in the sands! Turns out the back was down a bit but the front was down a lot - 10 psi. Amazingly I didn't notice on the road.

On pumping up (the £9 compressor worked fine) I also noticed a tell-tale spurt on the front tyre where the Slime fluid inside the tyre squirted out the sides (pic right) as presumably I hit washed-out creek edges on the Col Belkassim track the day before. The rim was not damaged so this suggested that even on moderate impacts (or possibly too low tyre pressures) the lack of the 'safety lip' (see graphic top of the page) was indeed allowing the tyre to collapse into the well or somehow lose its grip on the rim and so lose pressure - handily this was high lit by the Slime stains.

Whatever the cause was, it was time to scoot straight over a couple of hundred miles to Bikershome in Ouarzazate, put the tyre on the operating table and then probably slot in a tube (I didn't bring on). Unfortunately my urge to tick off a few tracks on the way went too far and I found myself up a pass (the deadly Tizi n Ouli Ousir - you don't want to go there!) with numerous problems including a flat front. I'd just ridden over some barely rideable rocks following a day of rocky tracks and in all the excitement hadn't kept up with the front tyre's slow leakage. I imagine the under-inflated tyre transferred the shocks to the rim while banging over the rocks which dinged enough to lose pressure. Luckily there was one bar on the mobile if I stood on the right spot and Peter from Bikershome came to the rescue that night.

Back at Ozt I would have like to have tested the wheel under water to see exactly where it was leaking, from the rim/tyre edge or out of the spokes but the dinged rim would have flawed the experiment. I peeled off the 5200 mastic with surprising ease (left, click to enlarge). There was some very slight Slime seepage under the glue in places. I tightened up some spokes and Peter flattened the ding and slotted in a tube. I also discovered the vital 14mm Allen key I had to buy especially to undo the front wheel (it seems not to be included in the OE Yam toolkit?!) had fallen out of its resting place. Most of my trips have these 'moments' but deary me, it was not my day!

So, what have I learned. Well, on the dirt a front tyre can have tough time, taking the brunt of the impacts. I don't ride hard, especially when alone, but for whatever reason, on a long trip there'll always be times when you take a frontal hit - rock, pothole, whatever - that you don't react to quickly enough. I now know a safety lip on the front is probably important up to the point where a front rim gets slightly dented - then unless you can bash it back you're stuffed and will need a tube. After this episode I continued watched the tyre pressures more closely and kept them at near road tyre pressures, Moroccan tracks being mostly rocky - and me being limited in the means to repair any flats.

As has been mentioned on the HU discussion thread, for some reason tubeless 21s have a bad reputation with holding their air and outfits like Woody's in the US which convert other spoked rims sizes don't do 21s any more. Could it be the relatively narrow tyre profile of a 21-incher in relation to its height (for the same average tyre carcass thickness) allow it to 'cave in' under hits where a wider front - typically a 19" as on BMs - will take a hit 'flat' and maintain the seal? Is this why the new BMWs GS800 has tubes on its tyres (front 21") while the '650' version has a 19" but tubeless? Probably not - it's just a marketing thing.

As it happens i did spot an ancient Honda XLM the other day outside the cafe which reminded me that 21 tubeless fronts did exists back in the 1980s. I ran with one on my first Sahara tour (pic right about 20 years ago) and recall no tyre problems, but I don't remember if the owner fitted tubes. I really must get my memory upgraded!

Would the Tubliss liner mentioned above have faired better? One imagines yes and that along with keeping tabs on the pressure my mastic-ing was possibly not good enough. Could the Slime have undermined the mastic's seal? Would a lipped rim off an old XLM work better? Don't know yet. A Tubliss liner would be the next easy thing to try, or just stepping back and surrendering to tubed fronts - for long range off-road travel it seems a proven, safer bet - or at least carrying a tube and the tools to fit it should a TL fail. Thing is, I've been there, in the bush and out of tubes and patches. This is why TL is a good idea and it's a shame I didn't get the chance to establish where the leak was on the front, sides or spokes.

The back tyre held up fine, kept its pressure following early loses and has 5mm left after 4200 miles so it looks like it'll last up to 6000 miles until it's on the limit. Not bad for a TKC from what I hear. The front has plenty of tread left.

Want to comment? Then please add it to the HU TL discussion for all to see. Thanks.