Tubeless conversion for spoked wheels

spurlock

New Member
I know this has been discussed some here before but wanted to share my experience with a recent conversion. All my life I've had spoked wheels and tubed tires, and done roadside repairs with patch kits, spare tubes and tire irons. So now that I have a Honda GB500 with no center stand and DID alloy rims the prospect of flats is a whole different challenge. I've had Akront alloys on bikes in years past that were no problem but these DID's need a bead breaker to get the tires off the rims. And with no centerstand, just getting the wheel off would be tough in a roadside repair situation. I like to be equipped to fix flats on the road so I looked into converting to tubeless. The advantage for me is beng able to just plug, pump, and get back home without even having to remove the wheel from the bike. Plus a 12V pump and plug kit are much easier to carry than patches, spare tube, pump, tire irons, and portable bead breaker, to say nothing of having to remove a wheel with no centerstand.

There are lots of online discussions about converting spoked wheels to tubeless. Methods include:
- sealing each individual spoke nipple with silicone seal (it works but is a god-awful mess and adjusting spoke tension is bound to break the seals.

- getting a tube from a smaller diameter wheel, cutting around the circumference, and laying it into the rim's drop center like a big rim strip, then laying a bead of sealant under each edge.

- sealing the entire drop center area with special tapes.

All these methods seem to work if done carefully. There are 14 pages of discussion on these methods in a forum here:
http://supermotojunkie.com/showthread.php?5090-Tubeless-for-under-10-00

I chose the tape method. First I looked at the Outex Tubeless Conversion Kit found on ebay or here:
http://www.ronin-cycles.com/product/27

I decided to go with another recommended tape, the 3M Extreme Sealing Tape #4412N, info here:
http://solutions.3m.com/wps/portal/3M/en_WW/VHB_Tapes/Home/Products/three/two/

This stuff is 2mm thick, extremely sticky and conforming, and withstands temperatures from -40 deg F to 200 deg F. I bought a 5 yd. x 2" wide roll for $31.54 here:
http://www.zoro.com/g/Extreme%20Sealing%20Tape/00090401/

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The Outex kit comes with mylar sticky dots to cover each spoke nipple to allow for future adjustment without damaging the sealing tape. Using the 3M tape on my rear wheel, I decided to try just trimming the existing rubber rim strip narrower to maximize tape contact area on the rim. After sanding the rim free of any corrosion and thoroughly cleaning with acetone followed by isopropyl alcohol, the rim and strip looked like this:

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3M recommends final cleaning with 50/50 isopropyl and water, so after one final wipe down I applied the tape. Per the Outex video demo I overlapped the tape near the valve stem hole, using a piece of the release paper between layers, then cut through both layers so the ends formed a perfect butt joint. I then added a short piece covering the joint and providing a double thickness for the valve stem. Here it is before trimming to width:

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I pressed the drop center areas thoroughly with a rubber roller, then used a razor knife to trim the edges just below the bead lip. Getting the excess tape off the rim is definitely a bit of work if it has been pressed at all.

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The valve stem is from NAPA Auto Parts:

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The front rim is a bit narrower so to get the most tape-to-rim contact I decided to cover each spoke nipple with 15mm dots punched from 10 mil plastic tape, rather than use the cut down rim strip. To make sure the nipples could still turn easily I stuck a 10mm dot punched from 4 mil plastic bag material in the center of each tape dot before sticking them over the nipples.

The tires mounted fine, I took special care to use rubber lube over the tape and tire beads to avoid pulling the edges of the tape loose. After inflating I wished I could see inside the tire at how the tape was conforming to the nipples and rim curves. As it turned out I got my wish as the rear tire had a nail hole in it! The previous owner had had a puncture and replaced the tube. So I pulled the tire off and took a good look. The tape looked great, tightly plastered around each nipple and seated perfectly to the curves of the drop center. It has only been a few days and about 200 miles, but so far air pressure is holding steady. I will report back if anything changes. No news will be good news.

Along with going tubeless I carry a 12v pump and Dynaplug tubeless tire plug kit (both from http://www.motopumps.com), and a "DonorHose" for setting the bead back on the rim if necessary after a flat (from https://www.bestrestproducts.com/p-45-donor-hose.aspx).

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The whole kit fits easily into a small tool bag I mounted to the side of the bike:

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So now I'm feeling much better equipped for a roadside flat, but hoping I never need to use the kit!

-Bill
 
I don't mean to disrespect a well researched topic, but seriously put a tube in it. It's too important to get wrong.

Rims designed for tubeless tires are a different shape to specifically reduce the risk of the tire rolling off the rim if it deflates. The rim beads are very different. Do not be tempted to use a tubeless tire without a tube on any rim not designed for tubeless tires. It may result in injury or something more serious.

Just as an example of the confusion this causes, early Suzuki GS wheels cannot be used without a tube but later ones can. People assume they are the same but they are not - as I discovered recently much to my chagrin.
 
teazer said:
I don't mean to disrespect a well researched topic, but seriously put a tube in it. It's too important to get wrong.

Rims designed for tubeless tires are a different shape to specifically reduce the risk of the tire rolling off the rim if it deflates. The rim beads are very different. Do not be tempted to use a tubeless tire without a tube on any rim not designed for tubeless tires. It may result in injury or something more serious.

Just as an example of the confusion this causes, early Suzuki GS wheels cannot be used without a tube but later ones can. People assume they are the same but they are not - as I discovered recently much to my chagrin.

Fair enough, but two points. The GB rims do have the raised lip inside the bead area, which is why it is such a bear to break the tire beads when dismounting. But more to your point, in my experience with tube type tires over the decades it was most common (and scary) when having flats at speed for the tube to deflate suddenly either from the tube ripping or the stem ripping out. I'm not sure how this would be worse with tubeless on tube-type rims. The real danger is not becoming aware of a puncture early. Perhaps a tire pressure monitoring system, though pricey, would be the best safety feature no matter the tire setup. But I take your point and just say if you're worried about it then stick to stock.

-Bill
 
Sounds like a combination of a tubeless conversion kit, to reduce/prevent air from leaking out spoke holes rapidly and running a tube as extra insurance would be the best of both worlds.

After riding 3 days to get to the Spring Thaw a couple years ago on my BMW R75, a few hours after arriving my front tire was flat.

Pulled off the tire and found a tiny blemish in the tube which finally let go. It was a defect, and could have been much worse of course if it had let go more quickly, and while I was racing through the Red River Gorge park at 100MPH on a loaded down bike.

Maybe next time I have the tires off either my XS or my BMW (the XS is due for fresh rubber soon) I'll add the tubeless conversion sealing insurance on the rim - but I still like that extra layer of rubber keeping the air where it belongs :)
 
Tim said:
Sounds like a combination of a tubeless conversion kit, to reduce/prevent air from leaking out spoke holes rapidly and running a tube as extra insurance would be the best of both worlds.

Yes, that's the point I maybe omitted, that with standard tube setups you have 36 leaks through the nipple centers, 36 more between nipples and rim, plus the valve stem. You are totally dependent on the tube to keep air in the tire. Hence the sudden deflation that often happens. Personally if I was going to stick with tubes I would also add the sealant as you suggest. But with my DID alloy rims that hold the tire bead securely I'm confident the tube is redundant as well as a PIA to repair roadside, so I'm comfortable saving about 1-1/2 lbs. of unsprung weight per wheel and going without.

-Bill
 
The rear wheel on my XV920 is chromed alloy, 40 spokes, came from a reputable aftermarket company presealed, stem installed and ready to mount the tubeless tire of my choice. Retains air pressure far better than most tubed tires I have owned.
I remember reading an article about the company and they used aerospace-grade polysulfide sealant, the same stuff as Boeing, Airbus and countless others use on their aircraft to stop leaks and retain cabin pressure at 35,000 feet. They would tape off a couple inch wide strip down the "tire" side (inside? outside?) of the rim and roll on the catalyzed sealant with a small paint roller over the nipples and let the stuff cure for a couple of days. I think they also had a fixture that drew vacuum as well but not certain that it would even be required.
Aside from being blessedly expensive, if you've never used the stuff, it stinks to high heaven and stickier than baby shit. Needs to have a clean surface before application, just the same as anything you're trying to stick together.
I wanted to do my front wheel as well - I'm running a tube inside a tubeless tire, but tubeless tire valve stems take a larger hole than a tube and I didn't want to eff up the rim in case I had to go back to a rim, but maybe...
By way of tubeless tires on spoked wheels history, the first recollection I have of them was at Daytona in 1967. One of the bikes competing had somehow sealed up their wheels and a couple of the bike magazines at the time had brief articles on the mod. I think the article extolled the virtues of lighter weight, a cooler running tire and what they surmised as less chance of getting a flat...
Pat
 
pacomotorstuff said:
I wanted to do my front wheel as well - I'm running a tube inside a tubeless tire, but tubeless tire valve stems take a larger hole than a tube and I didn't want to eff up the rim in case I had to go back to a rim, but maybe...

Pat

Yeah, I would never want to enlarge the stem hole. The NAPA MC stem I pictured above is same diameter as as standard tube stem.
-Bill
 
Hey, when and where did you find the GB500?

Several years ago at the Supershow, I saw a booth selling a product that converted a tubed tire into a tubeless. I can't remember the name of it but it cost $100 per wheel so I passed. Marketed towards MX riders but would work for street bikes.
 
DrJ said:
Hey, when and where did you find the GB500?

ebay and craigslist, my gloating here: http://www.dotheton.com/forum/index.php?topic=63846.msg728678#msg728678

-Bill
 
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