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rpilottx 04-13-2006 07:53 AM

Tubeless Conversion?
I need advice on converting the wheels on my 950S to tubeless. I know very little about tires and I am wondering if it is worth doing, cost, advantages/disadvantages etc.

Does anyone bother with doing the front wheel? My dealer has recommended doing the rear but not the front. Thanks for the input.

MortimerSickle 04-13-2006 08:41 AM


for you riders that entertain the thought of going tubeless,,,,Sun's 2.15 x21 is the only one of the rims that sports a safety bead and is the ONLY one we will seal- Woody's Wheel Works

This quote is from this thread. It might be of help.

sakurama 04-21-2006 07:58 AM

I just had a set of rims made up in 19/17 sizes and I decided to make them tubeless. I've put up a page showing how it's done on our site so feel free to check it out:

For those who feel it's too much work to click that link I'll give you a brief summary. Take your rims and scuff them with a scotchbrite pad to put a tooth on them - this is essential. Then clean them with alcohol to make sure they have no grease or oils on them - this too is essential as you want to make sure there's perfect adhesion.

Go to your office supply store and get a package of 3/4" dots - orange ones work best for obvious reasons but I had to use purple which is unfortunate. On the back I went with larger 1" ones but I think in retrospect I'd stay with the smaller ones. They don't have to be perfect you just want to keep the nipple free from the silicon you're going to slather on there so if you ever want to adjust the wheel you can. I've never adjusted a spoke in my life but I have it on good authority that there are people that do that.

This time I tried a very fancy and expensive aircraft epoxy from Aircraft Spruce that is used to seal gas tanks. I thought that this would have better adhesion and be more resilient and I think it would be but I went too thin on the rear wheel (2-3mm) and it pushed the sealent through and leaked. I didn't want to mix the stuff again so I just covered it with regular household silicon caulk. It's holding fine now. Since that sealant is so expensive I wanted to spread it over two sets of wheels and in retrospect I should have used it all. Now you know right? Mix the whole contents of both together and you'll have more than enough for one set of wheels. Now spread the stuff (wearing gloves since it's nasty stuff) into the center of the wheel keeping it off the bead area. Use a plastic scraper that you cut to fit that gap to evenly spread the sealant of choice over the spokes and go for about 5-7mm depth. If you use silicon you have only 10-15 minutes before the stuff starts to skin and smoothing it after will make it worse. The aircraft epoxy has a pretty long working time (an hour?) and is about the same consistency. Both can be cleaned with alcohol while wet. I've always done this on a balance stand because I have one but you could mount the wheels back in the bike and block it up on the centerstand.

Before you do this order some metal tubeless valve stems that bolt in - they're more durable and easier. If you want to be trick get the 90 ones for the front and point it to the side without the disk if you've removed one.

That's it. It works. It's not rocket science. I learned this from Kenny Buchanan so the source is solid. I have a few friends that race supermoto and they're all using the aircraft epoxy. I first did this 6 years ago with silicon on my boxer cafe bike and it's still holding air - better than any other bike I have I might add. If you use silicon you'll need two tubes for two wheels.

I've mentioned this in other threads and I believe Woody has as well but I don't recommend this for off road or for the 21" Conti TKC80 since it's a flimsy tire and I've had it lose air and roll right off the rim. I'm sure if you're using the bike with stock rims and tires on pavement you'd be fine.

Now, I'm going to ride my bike...


jp4evr 04-21-2006 03:03 PM

Tubeless w/ Silicon
how did you apply the silicon? Like the aircraft sealant or in a different pattern?

Btw - your aircraft sealant linky shows two products for sale. which one?

.... thanks for the tip. I ride a tiger and i hate patching tubes on that thing....

sakurama 04-21-2006 03:54 PM

I used the first one: PTS PROSEAL 890-CLASS B-TYPE II but silicon seems to work as well. The silicon is applied with a caulk gun and you just squeeze it on and then use the spreader to smooth it out. I think that I will just continue to use silicon from now on. In fact I just sealed up a set of supermoto wheels for my XR100 and used silicon...

lddave 04-21-2006 04:09 PM

I just sent mine to Woody.

MortimerSickle 04-21-2006 08:56 PM


Originally Posted by sakurama
I've mentioned this in other threads and I believe Woody has as well but I don't recommend this for off road or for the 21" Conti TKC80 since it's a flimsy tire and I've had it lose air and roll right off the rim.

Is this problem peculiar to this particular tire, or are tubeless 21" tires in general bad off-road?

woody's wheel works 04-22-2006 09:54 AM

Tubeless front 21''wheels and TKC-80s

Originally Posted by MortimerSickle
Is this problem peculiar to this particular tire, or are tubeless 21" tires in general bad off-road?

ok guys here's the latest info and best current advice i can give you,,,

first,,i am committed to matching your needs and expectations with what works,,,so that you have a BETTER experience,,

1... since i will only make rims tubeless that have a safety bead on them,,i am left with but one choice in the 21'' configuration,,a Sun 2.15 x21

2... although i have had incredible success with this rim on road bikes using tubeless road tires,,,i have found that using it for dirt has run into two major obstacles,,,the first is that the only tubeless tire available to us is the has proven IMHO to be marginal in meeting the high expectatations set for it....they are flimsy,,super soft and do not have a carcass suitable for plugging and going any distance on your plug,,,which was of course one of our main reasons for attempting this exercise

the second obstacle that has occured is that the Sun 2.15 x21 rim we need to use for the tubeless conversion business is fine for highway and fireroads but NOT as strong as its 1.85 x21 counterparts,,,it actually weighs less than a Sun 1.85x21!!!!,,,,, so for hard-core dual sport enthusiasts like Sakurama and Jean-Luc,,,,both of whom experienced what the outer limits of the TKC-80 tubeless conversion on the Sun 2.15 rims can bring,,,not knowing how tough these guys are on their bikes we did the tubeless thing,,,NOW,,,i am far more adamant about matching what i now know you NEED to get the job done as opposed to what sounds the dream of just plugging your tire and driving on,,,,

in conclusion,,,we currently do not have a matching beefy tubeless rim or tubeless tire worthy of getting the job done,,,,i have retrofitted both riders with the rims they should have had ,,,,had we known all we do right now..

PS...Sakurama...FYI,,funny how the universe works ,,just trued up your nice shiny POWDERCOATED gloss=black hub,,, trick SUPERLACED x3 supersized spokes n nipples on beefy Sun 1.85x21 black anodized awaits a current shipping address...the wheel ya shoulda gotten:wink:

Bermbuster 01-12-2008 06:45 AM

A little extra insurance
Good instructions, gave me the confidence to give it a go with a 19/17 converstion! I did develop a leak after a few weeks, and after dismounting the tire saw that the silicon was pushed straight through the paper dots and the threaded center of the spoke nipple. I stripped off all the old silicone and re-sealed as followed.

1. Filled the threaded end of the nipple with silicone, to eliminate an air space that the sealer can be forced down.There is enough residual lube on the threads that I don't feel it will interfere with the threads and any spoke tightening that becomes necessary.

2. I placed the paper dots on a piece of duct tape, then cut the duct tape and placed that over the nipple. Reason - the paper dots have bad glue and barely stick enough to stay flat - duct tape solves that, plus duct tape also may help with the "silicone push through" that I experienced.

3. Re-seal with silicone - easier ths time, as the dots/duct tape adhered much tighter.

4. I aso let it set several days, for the silicone to cure harder. I was anxious to ride, and a 24 hour cure time was likely too short - regardless of what the tube says. When removing the old silicone, it had hardened more than when I put the tires on the first time. . :D

RedRupert 09-28-2010 03:41 AM

Thanks sakurama!
1 Attachment(s)
I carried out tubeless conversion to my rear wheel back in September 2006. Since then I've covered 60,000 km without a puncture, until...

Spain, August 15th 2010. It was a Sunday, during the holiday month; I was miles from an open garage; on my own; and it was hot - too hot to be levering tyres.

However, thanks to you, it was fixed in a minute :freaky :

cagiva549 09-28-2010 04:38 AM

I had Woody's seal my 950 rim several years back , Mounted a new tire yesterday and still looking good . A couple roadside pluging's over the years . Sure beats tubes . SEYA

viola-tor 10-09-2010 07:53 AM

Just got a flat on my 19/17s in a construction zone. Now I have an excuse to do this mod! :thumb

While I'm at it I'm considering sealing the REAR 18" stock wheel, which I use for my off-road adventures clad with a knobby. It seems to me most flats happen on the rear, BUT, in Woody's post above I see the only knobby tire rated as "Tubeless" is the TKC80 (the TKC does not interest me). My fav tire is the Dunlop 908 which the sidewall says is a tube-type. DOH! Could/should I use the 908 as a tubeless tire??? Is it possible and/or advisable??? It would sure save some time, but I don't want to compromise safety tooooooo much (okay, maybe just a little. :evil). How about the MEFO rear? Is it rated tubed or tubeless? If it's tubeless it might be worth a try, I hear it's a great all-rounder tire.

Suggestions please. I'm DEF going to seal the 19/17's, just wondering if the 18" is worth it.

viola-tor 10-17-2010 09:14 AM

Okay, so I finally got a confirmation that the tubeless conversion WILL work on a stock 18" rear wheel running Dunlop 908's, so I'm going forward (albeit painfully slowly) with this.

I'm ordering 3 of these (one for 18" rear, two the 19/17s):

One question: Should I apply the the silicon OVER or UNDER the valve stem? Or perhaps leave a "hole" in the silicon so the valve stem mount bolt can be against the rim? Maybe it will become clear when I receive the valve stems...

Not sure if anyone is watching this thread, but I'll report back, could be a few weeks. I'm planning on using reg. caulk I guess. Cheap and available if I need to undo/redo (likely! :lol3).

SingleTrackMind 10-17-2010 10:53 AM

Pro Seal
Good on ya, Sakurama for using the ProSeal. That is by far the best sealant for this job and exactly what I plan to use when I do mine. I have a 1966 Mooney airplane with wet wing tanks sealed with that stuff, and they're still holding after 44 years. I recently installed new windows in the plane which are also sealed with that, and I had a bitch of a time removing the old sealant. It was still pliable and sticky.

ProSeal is available in smaller quantities than what Aircraft Spruce sells, for about $25 per tube. I used one tube to seal 4 windows, roughly 30 linear feet per bead, so one tube should easily do both wheels if you just seal around the nipples rather than try to fill the entire valley. The tubes are designed to be used with a pneumatic sealant gun, but I was able to just use a socket extension like a syringe plunger and it worked fine.

RedRupert 10-18-2010 02:47 AM


Originally Posted by viola-tor
One question: Should I apply the the silicon OVER or UNDER the valve stem? Or perhaps leave a "hole" in the silicon so the valve stem mount bolt can be against the rim? Maybe it will become clear when I receive the valve stems...

Over the valve stem. Just clear a passage for air once the silicon has been applied over the valve.

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