DIY Tubeless Conversion with Homebrew Sealant

This article describes my experience with going tubless the "guerrilla way". As Mr. Magura likes to say, it is "DIY all the way baby"! I started this project as a total tubeless noob. I used to ride with innertubes for years but I eventually got fed up with an increasing frequency of punctures on my home trails. After I had stopped changing tires more often than my underwear and settled on my favorite pair, I have decided to see what the magic of tubeless was all about. If you want to try a tubeless conversion but you are afraid of the unknowns of the process, perhaps you may find some inspiration here. This text is a weird mix of a description of what I did and of my instructions to anyone trying to do repeat, A to Z. I hereby apologize to all English speaking purists for bastardazing their native language.

I found my inspiration with my friends. I could not do it without help from Marpilli and other peeps at the Hucking Kitty Wheels and Tires forum. Thanks guys!

Homebrew Sealant

Right next to suitable rims and tires (that are not discussed here), a good sealant is an essential element for success. I could have gone with one of the off-the-shelf brands in my LBS, but man, have you seen those prices? The homebrew sealant described here requires a little work but the cost benefits are massive.

There are several recipes you can find on the intertoobz. I listened to my friends at the HK forums (see the Homebrew sealant thread) and went with a 2:1:1 mix of RV Antifreeze ($5 for a gallon, Autozone), Slime Tire Sealant (~$10 for 10oz, Autozone) and Latex caulk (~$2 for 10oz, Lowe's). Surprisingly, none of those ingredients is toxic. The RV antifreeze is not your typical engine antifreeze, it is meant to be added to potable water systems in RVs and boats and it smells like a popular girls'-out-night drink. I skipped the often recommended glitter since rumors had it the Slime had enough fiber in it. I can happily report that the sealant is quite messy even without the makeup part.

Homebrew sealant ingredients

I poured 5 oz of the Slime in a measuring cup, then drowned 5oz of latex caulk in it and semi-completed the potion with 5oz of the RV-A. Then I mixed it it all with a stick and poured the odd looking fluid into a storage container - an empty Coke bottle. 5 more oz of the RV-A are yet to be added at this point.

Mixing the stuff

This is what 5oz of slime + 5oz of caulk + 5oz of RFA looks like. Chances are, there will be large pieces of caulk sitting at the bottom of the measuring cup since the caulk is not easy to get dissolved quickly. I poured another 5oz of the RFA to the cup and mixed it with the stubborn flakes of caulk that would not go in the bottle easily the first time; and then poured this second batch to the Coke bottle.

Bottle of final product

Here we have a bottle of the magical fluid. If you are making your own, it is time to give it a good shake. And some more. And more. You do not want to see any flakes of the caulk sitting at the bottom, there are such flakes in the picture above. You want as homogeneous mixture as possible for the best results. Shake it baby, shake it!

Wheel Preparation

The goal of the next step is to prevent the rim from leaking air through spoke (or nipple? - use your personal preference) holes. I went the "guerilla way" - instead of using a costly dedicated tape, I used an el-cheapo 1" gorilla tape. I found it at Autozone.

Gorilla tape 1" wide

Unless you are about to convert a brand new wheel, you may have to remove the old rim tape first. Chances are, this is going to be a trivial task, for example a quality Velox tape should be easy to remove and should not not leave any sticky residue behind. However, if you or your wheel builder went with a cheap rim tape, you may experience a tough job just like I did when removing a Sette tape.

Old rim tape needs to go

Notice the gunk everywhere and loose threads stuck in it. That must have been a result of a combined effect of high pressure and relatively high temperatures that made the tape bleed glue and shed hair.

Cheap tape = tough gunk

This is what the Sette tape left behind - sticky goo, threads, some more sticky goo. I had to spend some quality time with a 99% isopropyl alcohol soaked rag and chemically and mechanically strip the goo. It is really important to get the sides of the rim clean, that is where the tire beads will be sealing the rim. If you leave mess there, air leaks will be abundant.

Rim Tape Installation

When I finished the tape removal job, I gorilla-taped the rim. I found great instructions in Marpilli's excellent thread again. Start 2-3" before the valve hole, finish 2-3" after the hole. Apply constant pressure and try to keep the tape in the dead center of the rim. My rim was wide - it was the Velocity P35 - so the job was easy. Later I will do a Stan's Flow and will report any differences in the procedure. If your rim is narrow though, you may have to trim the extra width of the tape with a razor blade after you are done applying the tape since it should not be covering the inner side walls of the rim.

Gorilla tape installed

My job with the tape was almost finished by now. The last remaining step was cutting a hole for the valve stem. A simple "X" shaped incission should have worked but I went a little anal there and cut a round hole with a razor blade.

 Hole

Please pardon the mess, my basement is not sterile, and fresh cleaned rims seem to be dust and dirt magnets. You should make sure your rim is clean before you proceed to the next step though otherwise you will get air leaks.

Install a valve stem and seat a tire bead

We are getting real close to having a real tubeless wheel. The next step is an installation of the valve stem. In my first attempt, I tried to use an old presta valve stem with a removable core that I cut off an old tube. This is what it looked like:

Valve from tube

This is how I applied some slime to its base before installing it:

Ready to go

When you install the valve stem, tighten the nut real tight to minimize air leaks.

Then I cleaned the bead with a rug soaked in 99% isopropyl alcohol to get nice and cleand contact surfaces. The picture below is focused at the wrong bead but you should get the idea.

Mount the tire and spray the bead with some soapy water (I am literally citing the master here). Now you have to hit the tire with a large volume of air quickly so it expands rapidly and the tire bead gets pressed against the rim sides, sealing the gap before air can escape there. If the influx of air is not explosive enough, the bead will not get seated, the gaps will not close and you will be pumping air in an through the tire without any effect.

In my experience, a floor pump will not get the job done the first time you do this.  This is where an air compressor comes handy. Or, if you are compressor-deprived like me, a CO2 inflator may do the job.

With or without the valve core installed, inflate the tire rapidly. You should see the tire inflate, hear a typical popping sound, and, hopefully, the tire would retain air pressure for at least a while. If it leaks air quickly, do not panic (yet). Even if it looks like the bead is seated for 20-30 PSI, in my experience it takes at least 40 but typically almost 50 PSI to get the ultimate "gunshot pop sound". I had to get busy with a floor pump to get to that pressure.

With a dozen of strokes of a floor pump, I inflated the tire to 50 PSI. Now came the time to check for the initial air leaks. The soapy water produces bubbles where air escapes. Wet the bead some more to see them bubbles better. With this first wheel, the bead was fine and tight, but the stem was leaking air badly:

Red alert - we are leaking air!

Seeing this, I chickened out, stopped and bought me real tubeless valve stems. Chances are, with sealant in the tire, it would have worked just fine; but I did not want to risk it and be replacing the valve stem with messy sealant already in the wheel. I have heard many reports of success with this method though, do not be afraid to give it a shot.

$18 later, I had this pair of new shiny stems ready. IMHO, any tubeless stem should work just fine, this brand was what a local LBS had in stock.

Tubeless conversion valve

I broke the bead, removed the old stem and installed the new one.

Installation

 Shiny! Now I had to seat the bead again. Luckily for my wallet (those CO2 cartridges are not free), I managed to get the bead pop with just a floor pump. A few fast strokes should get the job done now when the tire knows what it is like to be tubeless. :)

Adding Sealant

Here comes the messy part. Most people are likely more talented than me and will be able to create less mess but in my humble opinion, some mess is granted when filling the tire with sealant. For my meaty 650b 2.4 tire, I went with a bit more than 3.5 oz. Be alert, do not do this on your brand new shag carpet or on you leather sofa. Having the right tools for the job also helps a lot. Get yourself a large syringe with clear flexible vinyl tubing. Marpilli recommends this cheap tool for oil/gas mixing that he found in is local Walmart. Since there is no such thing as a local Walmart in most suburbs of Boston, I ordered the same item at Amazon. 

I use skinny Presta valves and the supplied tubing was too wide to fit the stem without leaks so I came up with this little trick: I took one of them plastic screw-on stem caps, cut the round top section off and pushed it in the hose.

The tubing then had a nice tight interface against the stem so I could inject the sealant in the tire without any leaks.

I have to be honest with you here - I was not patient to wait for the syringe to arrive and tried to pour sealant to the tire right from the cup. I broke the bead and tried to pour it in and the result was pretty disastrous. That green monster was leaking out of the tire around the loose bead like crazy. I eventually managed to get enough sealant in there and made the bead pop with a floor pump but the mess on the floor was real bad. Do not try this method at home and get yourself a syringe. The first reader who sends me a video of him pouring sealant into tire from a measuring cup without any leaks wins $1.

Stopping Air Leaks

The mess is over, hurrah! Making air stay in the tire is the last step of the conversion. Of course, I discovered new holes in the side walls right after I had added sealant. When you up the pressure to 50 PSI, the air will find its way out through weak spots and the leaks will become pretty audible. Now it is time for the messy sealant to shine - you have to shake the wheel like crazy to cover all inner surfaces, tilt it so the sealant gets to cover any holes and punctures, shake and tilt, rinse and repeat. I had the best results plugging the leaks when I lovered the pressure to 17-18 PSI. I shook/tilted the wheel vigorously until any audible leaks disappeared and kept it at that pressure for a few hours. Then I incrementally went to 25, 30, 40 and 50 PSI again and repeated the process until no more leaks were heard and when no air leaks were detectable with soap water any more. IMHO going with 50 PSI directly will make air blow hard through larger holes, preventing the sealant to get its job done. Incremental pressure increases gave me a tire that kept its air pressure for days.

 

Voila, here she is! A pretty meaty chunky bossy tubeless 650b tire! I will be able to report trail experiences when my trails become rideable again.

Wheel #2

My first wheel was easy, it was an almost new and a very nice wide rim that was a pleasure to convert. The second wheel, however, has been a bit of a challenge. It is a 650b ZTR Flow that has seen its share of rock strikes. It is beaten. The tire - a Schwalbe Nobby Nic 2.25 - also seems less cooperative than the big smooth Vee Rubber Trail Taker. The wheel is still in the shop when I am writing this, I have finished it only a few hours ago and it may still have a few miniscule leaks. Even so, it is almost ready to be ridden therefore I can share the differences in the experience.

Because of the dings, I felt compelled to straighten the side wall of the rim in a few spots. A rubber mallet and a straight piece of hard wood did an acceptable job. I used a Velox rim tape when I built this wheel and unlike the Sette, it came off quickly and without mess. I had to be more careful when applying the guerilla tape since the inner width of the rim was almost exactly the same as the width of the tape, there was very little room for error there. Just like with the first wheel, I had to use a CO2 cartridge for the initial bead seating, but all subsequent attempts worked fine with just a floor pump. Adding sealant with the syringe was much easier than without it, those two experiences cannot really compare. For some reason, however, the area around the stem valve was leaking air much worse than my first ghetto stem. The leak was effectively stopped by sealant though. I now believe that my first stem would have worked just fine had I had the balls to commit to it. I have seen more leaks around this beaten rim but careful tilting and shaking and pressure increases seem to have worked. 

24+ Hours Later

The sidewalls of the Nobby Nic have more holes than my favorite brand of Swiss cheese. Eventually, all those tiny holes got sealed and the tire seems to be holding air just fine now. It is nice to see that the sealant works!

A ride later

I eventually ran out of beginner's luck. During the first ride out, I lost air in the Nobby Nic and punched a hole through the gorilla rim tape over a nipple hole. I fixed that. Then the tire began leaking air from a sidewall like crazy. I could not get it to seal, the air leak was too strong and in a bad spot near a bead. At the same time, the valve stem fell apart at the base where the rubber boot separated from the stem. Basically, everything that could have gone wrong went wrong and my frustration got sky high. I replaced the valve with one from an old tube but could not get the leaking sidewall to seal. Luckily Mr. Flying W came to the rescue - look at his tip for using rubber cement to seal porous casings. The jury is still out whether the Nobby Nic is a success or not but I believe I can see the light at the end of the tunnel now.

Conclusion

TL;DR? I hope you found at least some parts useful. Congratulations if you decided to try it yourself. The conversion is neither difficult nor expensive and the rewards are supposed to be sweet. I have to wait for the riding season to start to be able to judge how successful my conversion really was but I would love to hear your stories in the related HK thread. Come join us, now!

Cheers,

Sti