Higher Education: Tubeless 101
The very basics behind a tubeless-tire system
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Photos: Satchel Cronk
This is not a tutorial. There are plenty of those out there already. In fact, I’ll embed a couple of my favorite ones in this post, but not until the end. On the way there, we’ll be doing something of a pre-tutorial. Covering a few fundamentals that, even if you already know how to complete a tubeless tire setup, may make the process easier, help if you run into trouble, or just deepen your understanding of what exactly is going on down there.
First, let’s talk about sealant. Stan’s is a common enough brand of sealant that it has become generic, and may be how you’ll hear riders refer to it. Though there are a few unique alternatives, the majority (including Stan’s) use liquid latex as their main active ingredient. They also have other stuff in there, both liquid and solid, so you have to shake it like homestyle orange juice before adding it (usually about two fluid ounces) to your tire.
Latex, as we know, is an extremely stretchy material that, even when very thin, will not let liquid or air through. That serves two primary purposes in a bike tire. The one we think about most is sealing punctures. It will allow you to roll over a nearly endless quantity of nature’s spike strips as long as it remains liquid, which is usually 2 to 5 months depending on the size of your tire, how much you put in, and how much might have escaped through larger punctures before it finally sealed or you finally plug it (which we’ll get to later). The other purpose is filling any imperfections in the seal around the valve or around the tire’s “bead,” the inner edges that sit against the rim.
It also, unfortunately, can seal the valve itself, so when inflating a tubeless tire, be sure the wheel is not rotated in a way that leaves the valve at the bottom where any pressure loss could suck sealant into the valve. Thankfully, the core inside the valve can be removed and cleaned. In fact, you may want to get used to removing your valve core anyway because it can be the easiest way to add sealant after those 2 to 5 months because you don’t have to unseal the rim from the tire. And let’s move on to the tire. This valve talk was getting dangerously close to a tutorial.
Before tubeless tires became ubiquitous on bikes down even in the three-digit price range, most tires were not tubeless-ready. Neither were most rims, but we’ll get to that later too. Stan’s, bless their hearts, made conversion kits that would allow you to go tubeless with almost any tire and wheel combo, but they required a finicky rubber rim strip and would often leave your non-tubeless tires’ sidewalls oozing tiny dots of white sealant. Shelling out for actual tubeless tires makes a difference in a few ways. The “casing” of the tire, which is essentially the tire’s body, is more robust and naturally air-tight, so neither air nor sealant will seep through it. Also, the bead diameter is measured with more precision at manufacturing and is made of a material less likely to stretch. It also has a wider, smoother surface at its base so it can make a more reliable contact with the rim, which we’ll get to now.
A tubeless rim doesn’t necessarily look different from a traditional rim. Years ago, some rims went to great lengths to have a structurally sealed outer wall because spoke holes, of course, prevent a tire from sealing. But the bike industry has agreed that lining the rim with certain types of tape will do the trick. Tape is yet another thing we’ll get to later. Taped or not, tubeless rims do have one thing in common. The surfaces on the either side of that outer wall are, like the tire beads, constructed to an exact diameter to ensure a tight-but-not-too-tight fit. The actual shape is slightly different between rim brands, and some even have patented “ramps” or sometimes “lips” that lead up from the center of the rim (which is lowered to give the tire bead enough slack to be installed). Something important to remember is that it is this surface that handles the seal. The walls of the rim (confusingly also called beads) are not what makes the actual seal. Sure, they help, but they really just keep the tire on the rim.
Its’ one reason why some rims can be hookless-bead and others are hook-bead. Most carbon-fiber rims are hookless-bead and most aluminum rims are hook-bead. This isn’t necessarily all that important with regards to how tubeless works, other than determining the proper-size rim tape.
Tape made specifically for sealing tubeless bike rims is made of a thin, stiff, even slightly brittle plastic-like material. It has to be stiff because otherwise, the pressure would force it into the spoke holes and it would eventually tear. Before tubeless, we would use a canvas tape that was more flexible, but not air-tight. Rim tape comes in several widths, and measuring can be tricky if you have a hook-bead rim because it needs to go from wall to wall, but it will fall short if it is only as wide as the distance between the hooks.
Tubeless tape doesn’t have to extend up the rim beads because, again, the seal is at the base, but it should extend as close to those rim beads as possible. One easy way to achieve this is by using Gorilla Tape. It is cheap, plenty strong and slightly more flexible. But conveniently, you can tear it to the exact width you need. The main issue is that it tends to leave a residue that can complicate tape re-application, especially if you go to the stiffer traditional rim tape which happens to be less likely to leave a residue. But once it’s installed, Gorilla Tape’s softer structure makes it a little easier to poke the hole for the valve. It’s easy to tear purpose-built rim tape if you’re not careful, but with a small pilot hole, you can just push the valve through Gorilla Tape.
Tubeless valves were once proprietary to the rim manufacturer, but modern systems are more user-friendly. If a valve is long enough to fit through the rim (anything around 44mm is probably right), it’ll work. All tubeless valves are presta-style, which you’re probably familiar with by now. But one thing that’s possibly unique about tubeless valves is their removable cores. Just below the tip that you unthread to add air, there is a larger threaded piece with two flat sides that can accept a tiny tool.
A presta-valve-core removal tool is a must-have once you go tubeless, and some valves integrate the tool into the cap. Removing the valve core is useful if you are adding sealant, but also when you are initially “seating” the tire, which means bedding the beads in place on the rim so it makes a seal and sits evenly around its entire circumference. If you are ever having difficulty getting a tire to seat, removing the valve core before pumping will allow more air to enter more quickly. And that topic is pretty well seated in the pump discussion, but we’ll briefly talk about plugs first because I don’t have a good segue to get us there.
Plugs are a benefit of using tubeless we often overlook. With sealant in the tire ready to help, a tubeless plug is able to seal holes far quicker than an old glued inner tube patch. Usually made of gooey, unvulcanized rubber, tire plugs are soft enough to squeeze into oddly shaped punctures and fill them up leaving very little room for air. But they have a usually fibrous structure that allows you to exert a lot of force to insert them. Many plug kits tend to leave you with the bare minimum quantity of plugs, so it’s good to carry extras. In the most common type of flat, a pinch flat, you may do enough damage to put two holes in the tire, and each may be large enough to require several plugs. And especially if you aren’t well practiced in plug insertion, you may find yourself wasting one or two and needing extras. Plugs are lighter than an extra spare tube, so bring more than you think you need.
So, it’s not always necessary, but going tubeless is a good excuse to buy an air compressor if you don’t already have one. Beyond being useful for countless non-bike-related things, the speed with which they inflate is helpful when seating a tire because you often rely on immediate and sustained outward force to push the tire beads onto the rim surface where they seat, create a seal, and allow you to begin to add pressure. There are also floor pumps generally called “charger” pumps that include a separate chamber that you can use the pump itself to pressurize and then release all at once to mimic the action of an air compressor. Whichever approach appeals to you will work, whether it’s the automatic, versatile compressor or the quiet, portable and slightly less expensive charger pump. Of course, with nice, wrinkle-free tires and well-taped rims, you can often get a tire to seat without the help of a compressor or a charger pump, so give it a try with your existing pump and you may not need to look any further.
So, I promised some tutorials, and now that you understand the elements of tubeless, these will feel more intuitive to follow. This video below covers rim-tape installation. Because it’s produced by Stan’s, it is promoting their tubeless tape, but the same rules apply if you decide to go for the Gorilla Tape approach.
Now once tape is installed, the tire installation comes next, complete with adding sealant and seating the tire. We would add to this, that once the tire is fully seated, spinning the tire slowly in your hands will circulate the sealant so that it catches and fills any small leaks that may be at the bead after install.
And with that, you are ready to roll. And if you already were, hopefully you’re also a little wiser about what got you there.
Photos: Ryan Palmer