If you’re about to convert to tubeless (good on ya), I’m assuming you’ve read or watched a few tutorials on the topic already. What follows is NOT a comprehensive tutorial - instead I’m noting tips I’ve learned through experience, that I seldom hear elsewhere.
Rim taping
If it isn’t obvious: There’s a difference between a rim strip, which is non-adhesive, and rim tape. Many rims come with rim strips, but relatively few come with rim tape, which effectively prevents air from leaking through your spoke holes. Generally, you must remove any rim strip from your rim before attempting to tape the rim. There are exceptions: For example, on WTB TCS 2.0 rims, they specify you should tape OVER the rim strip (“Solid Strip”), which will prevent broken spokes from damaging your rim tape seal.
Before taping, I recommend wiping the rim clean with isopropyl alcohol. Pull the tape tight as you progress around the wheel - the tightness of the tape is the main determinant for the effectiveness of the seal. For MTB pressures (<30psi), 1 loop of Stan’s overlapping at the valve core is sufficient. For higher road pressures, it’s best to use 2 loops, again overlapping at the valve core. Cut the tape cleanly and diagonally. Then use a tire lever to push the edges of the tape down onto the rim from the inside - you don’t want your tape competing with your tire for a spot on the rim’s locking surface. For an extra-good tape job, you can install a tube (and tire) after your tape job and inflate it to maximum rated PSI, leaving it overnight before removing the tube and continuing with installation. This applies extra pressure to the tape.
In a pinch, you CAN use Gorilla tape on alloy rims. However, it’s thicker and heavier than purpose-built rim tape, and it leaves behind a residue that is very difficult to remove (I use a pen, a paper towel and Goo Gone, and it takes forever). Gorilla tape is not recommended on carbon rims - according to my local bike shop mechanic, Gorilla tape adhesive can pull the actual fibers out of the carbon weave upon removal. Use Stan’s tape or something instead.
Today I’m cheating - my rims came pre-taped. DT Swiss knows what’s up.
Valve stems
It’s totally possible to DIY your own stems from old tubes (which saves you $10-15), and they seem to seal just as well as the official offerings.
If you’re going this route, it’s best if the stem core is removable. Having removable core helps you in 2 ways: (1) It can help you push more air into the tire faster when it’s time to seat the tire bead on the rim; and (2) You can use it to inject sealant, which is easier and cleaner than dumping sealant into the unseated part of the tire. Here’s how you tell if your stem core is removable:
Here’s how to cut a good valve out of an old tube: Stick the stem in the rim and try to match the shape of the seal to the shape of the rim. Do this a little bit at a time and keep testing the fit. Better to cut a little too little and cut again than to waste a perfectly good valve. (tiny leaks will often seal up with tubeless goop).
Many tubeless stem bases I see in the aftermarket have a minimalistic rounded profile to help them seal completely against the rim well - this works great. However, if you’re going for a squarer profile for the cut, it can help to make the cut longer along the arc of the rim to discourage the stem from spinning when you’re applying twisting forces to the stem in the rim (e.g. while tightening the removable core). Do what seems to mesh best with the geometry of your rim, and that will help you minimize the sealant required to seal the area around the stem reliably.
Some riders advise cranking the nut on the valve stem at least a quarter turn with pliers beyond finger-tight to ensure a good seal. I have never needed to do that to achieve a seal at the stem, and I’m a little bit worried that doing so might make it harder to remove the stem in a trailside repair. Experiment at your risk.
Mounting the tires
Remember, tires are directional. Sometimes the “ROTATION—->” is super faint - much fainter than the billboards on the sidewall (TCS EXO 3C etc.). It’s there (keep looking) unless it’s not. Google Image some pictures of the wheel mounted and you might at least find what other people think the direction should be. God forbid you check the manual that came with the tire.
Unless you want a bunch of extra practice with all this, align the tire logo to the valve core opening before you put the tire on the rim. I’m told this is for “style points”, but it also helps you locate the stem easily when working on the wheel. As you put the tire on, be careful not to agitate the tape you just applied.
Cool? Cool. So now we’re here - tire halfway mounted. Notice I’m still allowed on the rug because I haven’t added sealant yet - and neither should you (we’ll get to that later).
Although there are standards for everything, sometimes lax manufacturing tolerances make your life harder when it comes to getting the second bead onto the rim. If you’re having a hard time muscling the last bit of the bead onto the rim:
For a little extra clearance at the very end (which is often the toughest bit), make sure the bead of the tire is dropped into the rim all the way around. Start fitting the tire opposite the valve stem to make this easier.
Spray some diluted shampoo on the stubborn part of the rim as lubricant.
Using a tire lever should be a last resort, as it’s not recommended by tire manufacturers. I like my tire levers small, soft and plasticky to minimize the likelihood of damaging the rim, the tire or my poor fingers.
If you’re still having trouble getting the tire all the way onto the rim, don’t break your thumb in your attempts - we can simply declare this as an opportunity to support our local bike shop, who will probably be happy to help you pop that sucker on.
Inflating the tire and getting it to seal - without sealant
So now everything is in place, but it’s kinda floppy. DO NOT ADD SEALANT YET. First, do a “dry run” - try to inflate the tire to at least 30psi or so without sealant.
Beware, this is the time at which the “POP”s occur, which could freak out your fiancée and her cat sitting across from you in your 500sqft studio. Now is the time for eye protection.
To minimize POPs and maximize chances of sealing properly, you can try to pry the bead onto the higher, outer parts of the rim (see picture) before attempting to inflate.
You could also pull your removable valve core to allow air to flow faster from your inflator into your tire, increasing the chances of a seal. If you don’t have a valve core removal tool - well, frankly, you probably do, but it’s easy to lose in the bottom of a tool drawer or at the end of your multitool - you can get away with a pair of pliers, but try not to mar the threads or over tighten the core.
A more powerful trick is inflating the tire first using a tube inside, then deflating and breaking only 1 side of the bead to remove the tube. This way, when you reinflate you’re guaranteed to start with at least 1 side seated, which will increase air pushing on the unseated side.
You can cheat with an air compressor, pressurized air canister or shop pump. But a floor pump has always worked for me on a wide variety of setups.
If all else fails, you can seat the tire using a CO2 cartridge for quick a blast of air. Wear eye protection and thick insulating gloves when going this route. Do not attempt CO2 inflation with sealant in the tire. CO2 cartridges are endothermic and sealant doesn’t like to freeze, nor react with CO2. After the CO2 seats the tire, fully flush the CO2 out of the tire and inflate with a pump.
This dry run also gives you a low-risk chance to check the airtight fit of e.g. your DIY valve stems without spraying sealant everywhere. If you hear “SHHHHH”, you may have fitment issues the sealant can’t solve (e.g. with your DIY valve stem). But if it’s a gentle “hisssssss” and you get up to 30psi or so with a regular pump, sealant will probably get you to the finish line of holding air. Check the “witness line” on the tire is equally far from the rim all around - if not, you can massage it with your fingers or add/remove air to get the tire fully seated. Nice job, the hardest part is over.
That thin black rubber strip just above the rim is the witness line. Ignore the tan sealant bubbling out.
Adding (and removing) sealant
Position the valve at 7 o’clock or so when injecting sealant, and leave it there for the inflation. That way gravity will ensure the sealant won’t all gum up in one place. Most sealant manufacturers recommend 4oz for 29” wheels. I would start with less if you’re working with quality tires and a good tape job. You can even throw a bunch of sealant in there to seal the stem area and any other trouble spots, and later use the injector to suction out some of the surplus sealant from the bottom of the tire (put it back in the bottle, why not, this stuff is expensive!). You do NOT need to remove the tire to do this - only the valve core, with the stem positioned at 6 o’clock to form a nice puddle of sealant to suck up. “BuT DoeSn’T ThAt DeFeAt ThE POiNt oF TuBElEss SiNce It WoN’T AuToMatICallY SeAl PuNCtUrES?” Well, it’s a balance. Of course there will always be some residual liquid sealant that you cannot suction out, which will likely find its way to seal any small holes as you ride. Personally, I see no reason not to simply carry a 2oz tube of sealant in my pack and use it to top up whichever tire I need to if necessary, rather than carry an extra 6oz of rotating mass in both my tires all the time (which will evaporate and booger up faster in the tire anyway). When used with modern air-tight tire carcasses that fit precisely against rims, you just don’t need a much sealant as you do if you’re sealing up a tire with permeable sidewalls (e.g. non-tubeless-ready). 4oz therefore might be overkill, even for a 29er. Heck, some road tubeless setups can be run without any sealant at all. Your mileage may vary.
Inflating the tire and perfecting the seal - with sealant
A bounce here or there between vigorous pumps will take care of the odd hiss, which are probably near the valve stem if you’ve done a good job taping.
Once you get up to 30-40psi, the tire should be fully seated. Double-check the witness line. Shake, rattle and roll the tire, bouncing it on the ground, whatever you gotta do to achieve a good seal. An effective technique is to set the tire on the ground with the valve stem down, then flip it while hoisting it up into the air to dump sealant around the stem area inside the tire.
Go for a ride if you can, which will spread and smoosh that goop all over the inside of the tire. If you can’t ride for now, at least rotate the tire a few times every few hours to move the sealant around and prevent it from gumming up into sealant boogers.
What do I expect next?
It is common to lose a fair bit of pressure over the first 24 hours, especially if the tire just sits during that time without being ridden. This does not necessarily indicate that the leaks will not self-seal given more time. The seal may continue to improve as you ride. High quality tires and rims with tight tolerances might only lose 1-2psi per week once set up properly.
I have performed a few dozen tubeless installations or fixes in my life, which I realize is not as much as any shop mechanic. However, using the above tricks, I’ve never needed an air compressor, shop pump or air blast canister. $20 floor pump from Amazon works fine. I’ve even tried it with the high-volume portable Lezyne I have strapped to my bike, and it works great.
Bonus tips
Experiment with lower tire pressures! Running low pressures while tubeless will not increase rolling resistance as much as tubed setups.
Everyone knows tubeless tires tend to be more durable than tube tires, and it’s possible to fix them with plug kits (tread) or some stitches (sidewall). However, you should still carry a spare tube or two with you in the event of an unfixable gouge. Assuming you carry a spare tube with you at all times, Tubolito is one of the most cost-effective ways to shed weight from your kit on a ride (even though it’s a lot to pay for a tube). I have one with me at all times and have yet to use one, but I have loaned it to other riders in need, who were impressed with the compactness and durability. I should really get a commission from those Tubolito guys.
Ride safely.