I don't think I like the DIY approach. Maybe it's the engineer in me but sealing air really needs the right surfaces and the right materials used in the right way. I've known enough things leak when the seals were designed to known criterea to go try the "slap enough paint on" approach. BMW must have looked at semi-liquid sealants, O-rings, diaphragms and a host of other ways to seal the tyre and eventually went for the idea of separating the mechanical and pneumatic. This is good engineering as it avoids dynamic seals (your spokes and rim flex so the seal must too) which will always leak even if you go for something like a diaphragm never mind semi-liquid stuff. For a good dynamic seal you need a diaphragm to make the seal effectively static or an O-ring type seal with the right compression throughout the movement range. Liquids have no compression and to me would leak as soon as the spokes flexed. How much is the big question.

Tyre repair gloop (basically water with suspended silicone blobs) is the equivalent of emptying the teapot down the sink. You'll think you blocked the plug hole, but come back in a few hours.....In a tyre repair the glue holds the plug (mechanical) while the rubber in compression does the sealing, hence it's a good seal.

I won't be doing this, but if you really do want to be the first (and lacking a tyre engineer to tell me otherwise), the pneumatic guy suggests keeping the rim tape. A least this will slow the flow rate if the silicone does open a leak path and will keep the seal on the spokes in compression and as static as possible.

Andy

BMW must have looked at semi-liquid sealants, O-rings, diaphragms and a host of other ways to seal

I must say fixing the spokes outside the rim seems the obvious and easy way round it - or cast wheels of course (which I read somewhere are lighter on the t/l GS650 compared to the tubed 800 - could be wrong).

Lashings of B&Q silicon sealant under the rim tape sounds a good and reverseable bodge (as the best bodges are) but I wonder if there is some alloy corrosion (the vinegary smell) or outdoor temps ageing element in the silicon? Maybe some gasket compound would be better but whatever, it would be prone to lift off with centrifugal forces at speed unless the rim tape was a giant hose clip.

Anyway, Tubliss seemed to have engineered a neat solution. With that the centrifugal (which I didn't consider before) is broadly with you.

Thanks for the SP on the Airman pump - landfill it is then. Still Screwfix sounds like a good place for a wander and it's right next to Ikea for the Mrs - everyone wins!

Ch

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Morocco Overland 4 (2025) • Trans Morocco Trail

Threewheelbonnie,
I'm with you on this, I would rather put my trust in the tyre companies than someone who has tried a bodge and got away with it. OK if you are in the middle of nowhere and you have to find a fix somehow and then get the correct repair done as soon as you can.
I know there are those that will say that they have been using this or that for ages on the road but you don't get any test data to say what the limits are and what kind of bikes that are used.
Cheers
Ian

Slime and Ride-On are designed to be used prophylactically. Have you had bad luck with Slime? I've used it for maybe ten years now. And though it does not always work 100% of the time, it has worked many times. In Baja, cactus can be a problem. Slime works pretty good at sealing these small punctures. Also, things like small staples and finishing nails too.

Slime, if nothing else, can slow down rapid air loss you can get with a tube. Not good when fully loaded on highway at 80 mph.

Andy,
Not to denigrate tire engineers, but this really is just not that complex or hard to manage. Experience messing with it over the years can be a good way to know what works and what won't.


Patrick

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Patrick passed Dec 2018. RIP Patrick!

Sealing rims is a great way to avoid having to pull wheels off and patch tubes. This has been done successfully for a long time. I first heard of it in about 1998 on the Yahoo Triumph Tiger list. A really S. African guy, really good mechanic and tour operator, sealed up the rims on his rental Tigers. Worked out well from what I understand.

Woody's Wheel Works can do it too (for US guys) and I'm sure any good wheel builder can seal up rims properly. I did mine myself. I have not finished the project yet. But will in near future, and will report back!

I have sealed the rims on my DR650 ... can't find the "after" pics..... I will be changing tires soon and will post the pics of what they look like with sealer on there. I did this mostly to avoid rapid air loss.

Most rims will hold the bead solid and do not need a tube to keep them
in place. Could a really hard hit unseat the bead? Regards my DR650, I don't know for sure.

The product I used is called:
3M Marine Adhesive Sealant 5200

Here is what 3M claim:
~~~~~~~~~~~~~~~~~
Watertight Bonding/Sealing of Fiberglass and Wood.

Ideal for Through-Hull and Deck Fittings and Deck to
Hull Joints.

Flexible

Cures in 7 days

~~~~~~~~~~~~~~~

I totally trust 3M, they make great products. This stuff is not some
ordinary Silicone sealer. It's tough as Hell and adheres to the Aluminum very very well. I tried to peel it off the spoke nipples after it
had cured for a few days (meant to cure a week) I couldn't get it off! Still flexible but sticks in place! This stuff is PERMANENT!

Regards spokes:
Once the sealer is on and fully cured, the spokes should not move, therefore may not ever need adjustment again. (theoretically ) Time will tell. My bike has only done 4000 miles since I sealed them and like I said, I have not finished the job yet and am still running a tube. Spokes all good so far.

I'm still running a tube. I did this initially to slow rapid air loss. At some point I will go tubeless and install a tubeless style valve stem and see how it holds. Other projects in the way at the moment. I have a spare set of wheels to "experiment" on.

Patrick

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Patrick passed Dec 2018. RIP Patrick!

Good on you M-Dog. Interesting to hear someone has tried it, can actually recommend a product and that the idea has been around for ages.

Whip that tube out and take it round the block pronto, what are you waiting for?!

the spokes should not move, therefore may not ever need adjustment again. (theoretically...

I think it could be theoretically because it assumes that spoke loosening only happens at the now sealed up nipple. I have a feeling a spoke can simply 'stretch' along its entire length. Dont they normally break at the hub end? i cant remember.

Not sure Woody's is still doing it is he? See: WoodysWheelWorks.com - under KTM 950 Wheels
He mentions the complexities of sealant and centrifugal force which occurred to me earlier.

I would rather put my trust in the tyre companies than someone who has tried a bodge and got away with it.

Ian, we're not talking about messing around with trusted tyres but sealing wheel rims. The tyre is not affected except that it now runs cooler and deflates more slowly on puncture. In the old days what has come to be known as 'adventure motorcycling' was all about what I call 'bodging' - aka experimentation.
Of course a proper tubeless rim would be best to save all this messing about with 3M gloop, but on the sort of bikes I like they are rare at present. I was sceptical about tubeless on bikes for overlanding but am now converted enough to give it a try. As we all know punctures are the most common breakdown we'll experience on the road. Decent proven TL tyres like TKC80s exist so IMO it's time to make spoked rims catch up with 3M or Tubliss.

Ch

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Morocco Overland 4 (2025) • Trans Morocco Trail

Hey guys, I am pleased to report Woody's is still sealing rims here in Denver. I just got my wheels back- new rims, spokes, nipples- they look amazing. Problem is, Woody explained they are only sealing the 19" wheel, not the 21." Woody gave me a tour of the new shop. To seal the rear wheel they use a type of silicone that takes some 48 hours to set. They prefer not to seal the front rim as they had several failures in the past. They are currently working on an ironclad solution for the 21'' rim. Woody advises carrying a tube in case the sealing fails, though he says they have the rear wheel dialed in these days. Woody is semi-retired now and his Son Chris is stepping in. They are both terrific fellows and their product is fantastic. Patrick, if you get that sealant thing worked out I imagine you could make quite a bundle on the side sealing West Coast rims! I had 4 punctures over the last 50,000 miles- the rear tire EVERY time. I look forward to plugging instead of levering. Now watch, the next 4 punctures will surely be the FRONT- still tubed- tire! H.

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I'm glad this was mentioned! I had a wheel built by Woody, a really nice 2.15-21" for my R100 GS. It was sealed as mentioned previously. With a TKC-80, i had three blow-outs in as many days, all at 80MPH!! After the third, the sealant was completely de-laminated. i removed it and fitted a tube. I contacted Woody and was told that they have been having problems with the TKC's sealing onto the bead, i could never find a leak (soapy water) and all blow-outs were quite instant. Truth is, i'm really not sure what failed, the sealant or the tire.
If i was to seal a rim, i would use Sikoflex marine sealant. First buff the aluminum with a stainless wire wheel to give the sealant some tooth, apply sealant and let it cure. Sikoflex will stick to aluminum permanantly, so this is a one way trip! Remember that the space where the spokes go is required for removing the tire, so your sealant could easily become damaged if your not careful.

... was told that they have been having problems with the TKC's sealing onto the bead..


Thanks for reminder as I'm about to try this. I presume you were using a TL TKC front, not an old TT or Tube Type (easily missed when ordering as I just found out)? Not that I'm sure what the difference in bead surfaces might be but I imagine the carcass of a TL tyre is better made to deal with plugs: here a rear TL TKC is 30% more expensive than a TT in the same size which one hopes is reassuring.

i could never find a leak (soapy water) and all blow-outs were quite instant. Truth is, i'm really not sure what failed, the sealant or the tire.

Would the marginally bigger diametre of a 21" make more centrifugal force to help delaminate it if it was not cured/stuck on well? Though would not tyre pressure hold it in place [did i mention this earlier?]? Even if it delaminated all at once would enough air leak out via the nipples to cause and instant blow out as you say?

If i was to seal a rim, i would use Sikoflex marine sealant. First buff the aluminum with a stainless wire wheel to give the sealant some tooth, apply sealant and let it cure. Sikoflex will stick to aluminum permanantly, so this is a one way trip!

Found 'Sikaflex Sealant 291'. Looks like '3M 5200' but 30% cheaper.

Remember that the space where the spokes go is required for removing the tire, so your sealant could easily become damaged if your not careful.

I would put the rim tape back over the sealant and/or wrap on some duct tape.

Ch

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Morocco Overland 4 (2025) • Trans Morocco Trail

I was seriously considering changing tubes to tubeless on my ‘16 Africa Twin. Watched a few vids and all looked good. Rang Lightfoot Engineering in Melbourne- tyre and rim guru (my description, not his) and asked his opinion as to whether it was a good idea. Answer - No! He said that he doesn’t recommend it and has seen various issues arising from the conversion. I think he now refuses to do them. He spoke also about the BMW rims with offset spokes and said some of those rims ( depending on the bike’s year model) were not without problems either. He suggested that putting in bicycle tube sealant in through the valve of a tube ( if using them) adds a slight safety inclusion, hopefully creating a slower leak rather than a fast leak as can happen when tubes blow. Be careful of thickish tubes- added heat generation. It’s tubes for me. If I had a BM with the modern rim, I’d probably use tubeless though.

Your tyre guru's reaction is not uncommon from someone in the tyre and wheel trade but not offering this service.
Or are you saying he did it, but stopped? And if yes, what technique did he use?
I can see if it was unreliable, he'd have to stop letting customers down if he could not find a better way.
DIY, and you are your own boss.

And yes, squeezing sealant into the tube is commonly done.
Bottles of Slime or similar come with a Schrader nozzle to make it easy. I do it to all my tubed bikes; for a few quid it's a no-brainer. But I now hear from others and have found myself Slime etc can soften and delaminate the sealant. Won't use it now. If it's leaking a bit it has not been done right. Try again until it does. Slime/etc is a short cut that may bite back on some sealants.



BMW have had problem wheels (cracking alloys) since I first started biking, but what are the actual problems with BMW outboard spoke rims?
Is it to do with the spokes or the TL seal?
I certainly feel that outboard spokes (750GS below) are in a more vulnerable position in rocky terrain, and heavy bikes ridden hard or carelessly at too low psi or on soft-wall tyres will damage rims for sure.
A hard-riding KTM big-twin mate ruined his stock wheels.

Matters are over-complicated by attempting to seal a 'sieve' when a perfectly good bowl is sat right alongside!
Cast wheel does the job perfectly.
People will now jump in, parroting the 'spokes are better off-road' myth. On a 110-kilo KDX200, absolutely.
But on a GS12 or AT or Pan Am at way more than double the weight...?
It's an unfortunate clash of looks/marketing (spokes = rufty-tufty off-road) vs safety (TL).
The whole 'adventure motorcycling' phenomenon in a nutshell ;-)
You can add cost too: OE TL spoked rims using flanges or outboard cost way more.

Talking of ATwins, I DIY sealed the rear of my 2018 for a long desert trip with no complaints. Sat for a year and a half, it still held air.
https://adventure-motorcycling.com/2...-for-tubeless/


A 21-er upfront has historically been trickier to DIY; I would sooner get it professionally sealed with Airtight (see link below)

As you will know, the 1100 AT now has TLs all-round because inner tubes are an anachronism.
When did regular cars last use inner tubes?

The great thing is, converting to TL is a choice.
For a regular riding around where you can call in a recovery if you can't fix your own flat, why bother.
The crux is to do it well (link above) or get it done professionally.
I bet someone in Ozzie is offering such services.

For a travel bike operating alone out in the sticks, autonomy is important.
The ability to fix a roadside flat and be rolling again in 10 minutes adds peace of mind in the face of the many other challenges on the road.

Pages and pages on this interesting topic here.

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Morocco Overland 4 (2025) • Trans Morocco Trail

I agree...adventure motorcycling was borne out of the necessity to bodge and experiment...in fact, that's how a lot of proper solutions got developed and sold, and subsequently integrated into later models of that bike/product.

I am a huge fan of tubeless. BUT aside from the rim, tire choice is extremely important and complicated. Beyond the tread pattern of the TKC vs the Anakee, etc. You have to consider the sidewall strength, the composition of the plies, and number of the plies on both the sidewall and tread.

I luckily suffered only one puncture on my last trip, plugged it. There were quite a few sharp rocks in the Niger and Algeria that promised to shred my tire, but luck and a 5 ply tread on rear and front, supported by 5 ply tread on the sidewalls, absorbed the blows readily.

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edde
93 BMW K75s
www.motoedde.com

edde- what 5x5 tire were you running? Hope to talk to you before I return to Africa, am "doing" the west coast route this time before re-visiting the east coast. Later, H.

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I've had good and bad experiences with both slime and ultraseal. The issue seems to be a mixture of cure time and hole size. If the hole is small a small number of rubber bits block it, it cures quickly and you have a near permanant fix. If you get a big hole you get the "tea leaves in the sink" effect and get to do a proper fix after your next meal break. If you get a hole in a surface that moves or isn't flat (seam of a tube in my case) it simply doesn't work and the stuff is just messy. All in all though I can see practical advantages to this. I don't carry it as the Bonneville has very easy to change tubes, but for example with my dad's Guzzi running tubeless tyres on the worlds tightest tube type rims, Ultraseal would for sure be my first choice if he ever went more than a hundred miles from home.

Like I said, it's the engineer in me that likes to see proper testing, an affliction that no doubt does prevent progress that inventive people will naturally bypass. I've had one explosive blow out in my previous test driving career (I used to work for WABCO the brakes people), fortunately on an axle with twin tyres but the noise was enough. I can also change my tubes in next to no time, so no encouragment there I guess

The comments from the guys doing this in the US are interesting. The bigger the wheel the harder it is to seal, or is it the front position? The spoke flexing is different either way IMHO. A rear is going to flex it's spokes based mostly on engine torque applied? The ends of the spokes to me will "roll" in the rim, something the front also see's under braking? The front is subject more to impact type hits to the rim trying to push the spoke into the rim, making a gap a little like a poppet valve as the rim flexes? The longer the spoke the bigger the gap created when it moves, so the harder it is to keep your chosen seal in compression?

As a test routine, I'd want to seal the biggest rear I could and ride it off road so it see's impacts. Then I'd want to try the same size as a front, so 19-inch on a classic/Enfield? You'd at least be learning if it's the wheel loading or spoke length that limits your seal. Hopefully you find out if you've got a rolling or opening issue and can then add a suitable o-ring or flat seal to support the semi-liquid?

My other fear is changing the resonant frequency of the wheel by some stiffening of the rim to spoke joint. What's the chance of breaking a spoke now and after the seal starts acting as a damper? If a spoke breaks what are the chances of this causing a rapid tyre failure? Like I say, it's just the engineer in me that likes to see FMEA's and the like on safety critical items.

Good luck to the innovators out there

Andy

All good points Andy that make theoretical sense to me. You do wonder why matey has recoded front 21s failing - could be less tyre mass to absorb impacts (compared to a chunkier rear) and longer spokes like you say. But the only spokes I've ever broken were on the rear which takes much more load in an overland rather than racing scenario.

I do wonder about the loss of spoke-tensioning/repairing ability with the 3M method. May be fine on some fat highway cruiser but we're all about crap roads in poor countries and off roading with big loads. For years I always fitted my bikes with HD spokes on decent rims (if necessary) but on the last trip a custom HD re-spoke made things worse on mine (the other bikes - same models & load - had no breakages).

This is why for real world overlanding I think I might prefer the Tubliss liners - they are easy to reverse.

Ch

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Morocco Overland 4 (2025) • Trans Morocco Trail