Tubeless bicycle tire conversion/adventure

Tubeless bicycle tires? Like a car? Is it possible? Why should I try it? Yes, it’s possible, and lots of mountain bikers are raving about it. But it’s the last question, “Why?” that I lost sight of in my messy, expensive, fussy, and laborious pursuit of the mythical flat-free tire.

Initially, the “why?” was this: My touring bike gets too many flat tires. I am sick of patching and replacing tubes, so I thought it would be smart to get rid of the tubes. How obvious that seemed at the time! But it’s a little more complicated. Most bike tires aren’t designed to hold air without a tube, and even if the tire can be made to work without a tube, the tire itself can still get punctured.

Couldn’t I just get tougher tires and keep using tubes? Some bloggers brag about cycling across the country or around the world without a single flat tire. Their tires may wear like iron, but they also ride like iron. I like my supple tires that absorb the bumps of chip seal and smooth out the gravel roads. Out here in Oregon, I ride a lot of gravel roads.

Grinding gravel roads would seem to be rough duty for tires, but it’s roadside glass that shreds my tread and ventilates my inner tubes. I was considering buying some tougher tires, but decided to try running tubeless with the tires I have and like. Well, I like them other than they go flat all the time. There’s so much glass along the coast highway (Hwy 101) that I can’t ride 50 miles without getting a flat. Seriously. Every other time I ride on 101, my bike has a flat tire the next morning. They’re Serfas Drifter tires with “Flat Protection System” but it’s no match for the tiny slivers of glass that I pick out of the tread.

I considered the Stan’s brand of sealant system and a couple others. The conversion kits and sealant are pretty expensive, but if you Google “ghetto tubeless” there are recipes and instructions for going cheap.

experiment: tubeless tire conversion

First I removed my tire and marveled at the bits of glass I picked out of it. Then I cut the valve stem out of my inner tube and set that aside. I wrapped a few layers of electrical tape around the inside of my rim and put the tire back on. It wasn’t a very tight fit, so I added a few layers of duct tape over the electrical tape. I stuck the valve stem through the hole in the rim and mounted my tire again. Nice and tight this time.

Now the real fun. I mixed up a sealant concoction of latex caulk, windshield washer fluid, and RV water system anti-freeze. There are lots of recipes on the web, and if my time was worth anything, I could have bought gallons of commercial tire sealant in the time I wasted browsing recipes. And then it didn’t really work, anyway. My mix was about 4 parts latex caulk, 2 parts windshield wash, and 1 part propylene glycol (the non-toxic antifreeze stuff). It almost worked, but I’ll get to that.

Using a tire lever, I held the tire bead away from the rim and poured in 4-6 ounces (100-150 mL) of my syrup, which looked like thick white paint. I popped the bead back in place, wetted the tire and rim Windex, and pumped like crazy. The tire would not inflate.

My ever-helpful neighbor offered up his compressor, and that worked. The quick burst of air expanded the entire tire against the rim and it sealed to the rim almost perfectly. However, the gashes in my tread would spew geysers of white latex until the tire became soft again. As I returned to my garage, I repaid my neighbor’s kindness by painting his driveway with white splotches.

oozing tire sealant

I tried thickening my formula with wood flour, and that helped plug the holes, but I still could only get about 20 psi without a geyser. I rode around the neighborhood thinking that might help seal everything, but it only served to paint the road. And my bike. And my shoes.

leaving my mark

The next day, I went to the hardware store and bought some Slime tire sealant. I added 50 mL and it sealed the holes better. Now I could maintain 30+ psi, though the plugs of sealant would eject between 45 and 60 psi, at which point the leaks would hiss and spew until the pressure dropped to 20-30 psi. So I settled for 30 psi and went for a ride.

Slime to the rescue!

I did 26 miles, about half in the woods on gravel. I was concerned that the tire (I did the front only) would be sluggish on the road and would bottom out on gravel. I was pleasantly surprised on both accounts. I rode at my usual ~12 mph on the road and it felt normal, just maybe a little smoother. Climbing up and bombing down gravel roads was much more surefooted. Those mountain bikers are onto something good with the tubeless tire thing!

I should note that my tires are basically slicks. That’s one of the things I like about them. They suck on gravel, but so does every other tire I’ve ridden. Even mountain bike tires aren’t wide enough or luggy enough to grip gravel. Gravel is squirrelly, and since this bike also sees a lot of paved roads, I choose to ride tires that work well on pavement.

tubeless tire conversion

Fast forward to the next weekend, and my tire was still holding air. Impressive. There was a puddle of clear, slippery, viscous liquid on the floor, which I made out to be propylene glycol. Not sure how that separated from the paint + Slime and seeped out of my tire, but it was clear, not white or green.

I took another ride in the woods, and soon felt sure my luck was riding the other direction. The holes in my tread opened and spewed greenish paint before sealing again. This happenedt 20 or 30 times in 30 miles. I only had to stop and pump up my front tire a few times because it usually sealed within a few revolutions, but what a mess. I can’t imagine using this stuff without fenders. The spewing was continuous above about 45 psi, and sometimes wouldn’t stop until reaching about 15 psi, the lowest my pump registers. Fortunately, riding gravel at 15 psi is really comfy. Unfortunately, 15 psi makes pavement feel like wet sand. Good thing I only tried this on my front tire.

I know this can work, and I’m assuming it’s just a matter of putting the right potion in the tire. My rim and valve stem sealed fine; only the punctured tread is leaking, and that’s what the sealant is supposed to seal.

bubbling tire sealant

Back in the garage, I pried the tire from the rim again and removed what little paint was still sloshing around. Then I squirted 50 mL of Slime into the tire and inflated it again. The holes in the tread sealed instantly, and the tire is now holding 80 psi. That’s its maximum rating. With tubes, I’ve been running about 60 in front and 70 in back, so this should work.

There’s hope for my tubeless experiment. I’ll keep trying. I have a big bottle of Slime. If that runs out before I’m successful, I’ll just buy some Continental Gatorskins.