Helps evenly apply the tension to the valve stem. Not sure if it actually seals anything. Also stops you from scratching your paint, or worse, crunching a carbon wheel, with the external nut.
Sometimes I find an extra, short strip of tape on the inside at the valve stem gives a little more to seal against than a single layer. Not all valve stems fit well with all rims.
Pro tip for stubborn tires to pop: hairspray
+1 to this. Never seated my own tubeless tire. Never plan to.
Its not hard, really not hard at least with my wheels…
I’ve only paid to install once, it was 100 degrees F outside and a nail destroyed a tire about 30 miles from home. Luckily it happened in front of a bike shop.
I paid to have tape installed after trying myself and failing. It happened after Enve replaced rim under warranty - tire bead fail on a downhill, controlled stop, but left some road rash on rim.
Happy tubeless user on MTB and cyclocross/gravel for about 15 years. However, road tubeless can be a different beast, I have very mixed experiences with it.
My main issue with road tubeless is not so much mounting the tire but getting them off the rim again. Trying to fix a flat, e.g. put in a tube roadside, and not getting the tire off is the most frustrating experience. And Dynaplugs & co do not always help. the problem is really that you never really know if your rim-tire-sealant combo is a trouble maker or not. Just had to cut open a Pro One to get it off my Hunt rims. Hunt shipped the wheel pre-filled with a very sticky sealant. However, this wasn’t the first time I had to cut open a tire.
Not being able to fix a flat when out on a ride is really my main issue with it.
Still ride tubeless on the road …
(tip for non-sealing valves: mount them with some sealant applied around the base)
My wheels are tubeless ready, and after trying 4 different road tubeless tires (Pro One, S-Works, Sector 28, Zipp Tangente RT-25) I’ve never had a problem with:
I had 4 Sector 28s, and 3 of the 4 fit well but the 4th tire was out of spec and was too loose.
Favorite tire is S-Works but its expensive.
I absolutely LOVE road tubeless. To me, the increase in comfort and grip through using lower tire pressure is 100% worth it. And having done it once or twice, I now find it pretty easy. I’m using 30mm Schwalbe G-One Speeds. They have been great, even over very rough road surfaces and slamming into potholes that should make a LandRover cry. Just placed an order for a set of Schwalbe Pro One’s for summer use (hopefully on better roads).
A couple of tips:
– Whatever your problem is, it’s probably the rim tape. And if you’re sure it isn’t the rim tape, then it DEFINITELY is the rim tape. Don’t ask me how I know that. 
– I’m not a huge fan of Stan’s rim tape. It’s fine, but I like the DT Swiss rim tape better. Feels thicker and slightly easier to work with.
– I always do two layers of rim tape. Really make sure it’s flat and there are no bubbles.
– I second what someone said above: air escaping around the valve stem probably isn’t the valve: it’s the rim tape. [I TOLD YOU NOT TO ASK ME HOW I KNOW THAT!!!]
– That said, I have had issues with valves as well. Basically, I was convinced there was a leak from a valve stem not sealing properly (it was a Milkit valve), so I kept cranking down on the valve nut…until I managed to pull the conical plug from the bottom of the valve into the cavity of the rim itself. I’ve since switch to the Orange Seal valves and I absolutely adore them. They come in a great kit with everything you need. They include two types of rubber gaskets for the bottom of the valve. One is elongated, the other is conical. For my wheels (HED Ardennes), the elongated once fits perfectly into the rim channel. This prevents the valve from twisting when cranking down on the nut, or when installing and removing valve cores. If the elongated one doesn’t fit, the conical one will. And it is big and burly enough to not slip into the rim cavity.
– For mounting tires the first time, I can also recommend the Kool Stop Tire Bead Jack linked to above. It isn’t perfect, but it is useful and worth the money.
– I always use a bit of soapy water when first mounting the tires. You don’t need much. Only takes a second and is very helpful.
– I use an Airshot. Useful thing. Cheaper than a compressor or air tank (which it effectively is). But I recently bought a dedicated high volume pump for fat MTB tires, and that seems to work quite well, too.
– I inflate my tires, get the beads to pop into place, then inflate to 80 psi and wait a few hours. If the tires are holding most of the air, then I remove the valve cores and install the sealant through the valve. Works well. When installing sealant, I like to hang my wheels so the valve core is at 4 o’clock or 8 o’clock. That lets the sealant run down into the tire and helps to avoid sealant “backing up” and spilling out of the valve.
– Before installing a valve core, I dip it in sealant.
– When changing tires, I again hang the wheels with the valves at 4 or 8 o’clock, then release the air from the tire through the valve. (Hanging the wheel so the valves are slanted down allows the sealant to drain from the valve before you release the air. Otherwise your valve will spray sealant.) I then hang the wheels with the valves at 6 o’clock. Using the plunger and syringe assembly from a Milkit kit (love the system, but hate the valves), I suck out all the sealant. (Hanging the wheels with the valves at the bottom makes it easy to put the syringe straight in to capture the sealant at the bottom of the tire.) Then I can pop the bead on the tire and clear out any removing sealant with paper towel. No mess, no fuss.
Well, this is already too long, but those are my tips on road tubeless. (Shameless plug: I can’t speak highly enough about the Schwalbe G-One Speeds. Great tires.)
Best,
Adam
I have one set of NoTubes rims where tires refuse to seat if I put tubes in them. I took them to my bike shop and it took them half an hour to seat them and that was after smearing oil on them, something that made me cringe. I find tubes to be a lot of extra work.
You need to ditch those rims, then. When you get a hole that won’t seal, you’re screwed unless you can get a tube in. Gotta have the flexibility to do either or if you’re running tubeless.
You will eventually get a hole that won’t seal.
Good point, but it’s a cost-benefit issue. I’m not goint to worry about getting a puncture on this, my commuting bike. Its tires are pretty rugged and could be the cause of the problem. I’m relying on the sealant with hole plugs as a backup. Now that you’ve reminded me, I wonder where I put those hole plugs…
Oh yeah. No worries then. If you can’t repair a puncture on a commuter you’ve still got transport options!
In a lot of ways, tubeless makes more sense in a commuting setup than a road racing setup. Potholes/pinch flats are, unfortunately, endemic to many urban settings. Plus, the additional comfort you can get from running lower pressure on the commuter bike is not to be disregarded.
I’ve been experimenting with commuter tubeless a lot recently. Using almotions, thickslicks, kojaks, and wild run’rs. So far, I just can’t convince myself that tubeless has appreciable advantage over tubed in my locale (even though I really want to believe!). On the other hand, if my tires wouldn’t seat with tubes, I would be 100% on board with riding tubeless! Ha!
The urban setting is also where we race/train, so from my POV tubeless advantage applies to training, racing, and commuting.
A guy double flatted in the Land Park Crit Cat5 a couple weeks ago. I’ve double flatted - pothole pinch flats at 24mph - early into a double century on urban roads. In the western US we have small thorns (“goat heads”) that will flat tube tires but tubeless riders generally keep on riding or stop to remove thorn and keep on riding. On the DeathRide I got a goat head tube flat on front tire at 35mph near the bottom of the second (10 mile) descent. Group rides with the Gatorskin guys laughing at GP4KII flats and then they flat. So many stories from the roads…
Road tubeless isn’t perfect, but it’s much better than tubes for all the riding I do.
Yeah. I think I’ve said several times if Tribulus is a reality where you ride tubeless is something to consider.
You’re one of those riders…sounds like you get a puncture every couple of weeks. That sucks. Punctures are much less frequent for me. (touch wood) Like once a year. Except for gravel rides, the races I’ve done this year had very few potholes on the course (I want to say zero? But who knows?) And one of those was an Ultra cycling event! 
So lucky me.
I do see tribulus terristris once in a while but it’s not thick like it can be in many places.
But if you’re roads are crappy & you can’t dodge the potholes (front guy moves around, 2nd guy dodges, 3rd guy bunny hops, 4th guy oops)…gotta do something, for sure.
not this time of year, but yeah when riding outside in summer and fall its goat head season and all bets are off. We have a lot of wind on Wed rides, so fair bit of 25+mph riding on crappy roads when there is a tailwind. Its game on with a tailwind, usually putting out more power riding fast than when we are #struggling into headwind.
Also…I was watching a NorCal cycling video of the Bariani Road Race and those roads looked horrible. If that’s representative of what roads are like for most riders…I can’t believe anybody races less than a 28mm tire on those roads.
I’m racing this weekend.
100% I’m gonna get a flat. Total jinx.
all depends on how old the road is… some ride leaders will remind people to bring two tubes. The day after Nate was edged out by one of our Wed night guys, the local guy rode and titled his Strava ride “1 tube, 2 flats” ha ha. I’m running 25s and 26s for aero reasons, and occasionally 28s if they are true to size, but Conti GP4KII at 28 run about 32mm inflated and a little too wide for safety reasons. The European standard is 4mm of clearance on either side of the tire, measured at the chain stay.
Sorry for the jinx convo 
I just mounted up 2 sets of the new GP5000 TLs and didn’t use any sealant, as per their marketing claims. Risky, definitely. I’ve done 2 rides on fairly fantastic asphalt (we’re really lucky here in Germany) and the tires feel great. I’m always worried about the psychosomatic effect of trying new stuff but, man, those tires felt smooth and fast.
The tubeless set up on my Reynolds Assault with 28mm GP5000 TLs was a cakewalk.
However I had an all out brawl with getting a set of 25mm GP5000 TLs on my Hunt Aero30s.
wait whut?!? I haven’t seen this.
