Airtight Theory: Observations on Running Tubeless

Airtight Theory: Observations on Running Tubeless

Until I began running tubeless tires, I didn’t understand what the big deal was. I didn’t flat all the often and it didn’t seem like the ride quality of the tires I rode was in some way inferior.

Then I rode some wheels set up with tubeless tires. Here’s what I can report of the experience: I didn’t immediately feel a difference in the bike’s ride quality. The combination of full suspension and a 2.1-inch tire didn’t communicate anything significantly different from what I typically perceived. However, I did immediately notice an improvement in traction. after running the tires first with tubes then setting them up tubeless at exactly the same pressure, they offered better grip. And because you can run tubeless tires at lower pressures without risk of suffering a pinch flat, once I dropped the tire pressure by 5 psi, the trail-holding power of the tires fundamentally changed cornering.

I’d sooner give up my dropper post than go back to riding a mountain bike with tubes in its wheels.

With gravel riding, I’ve seen as big an improvement in comfort as traction and I’ve been able to discern no increase in rolling resistance. As someone who has ridden a few thousand miles on a touring bike running 35mm tires with tubes, the rolling resistance from running them at 60 psi convinced me that I’d never run a tire of that width at 40 psi and manage to pedal better than 20 mph. How times change.

So that’s the experience of riding them. What holds many riders back from making the switch to tubeless is setup and it’s not nearly as difficult as it sounds.

The shot above is of the once ubiquitous Mavic MA40. It was a reliable rim, but a great many tires didn’t go on the rim easily. Vittoria open tubulars required tire levers just for mounting. Why? The inner diameter of the rim was, when considered against some of its competition, rather large. The larger a rim’s inner diameter, the tougher it is to mount a tire.

Given how snug a tubeless tire must fit, it’s easy to conclude that you’ll need a crowbar to mount the rubber. That’s not the case.

You’ll notice that in the shot above there’s a deep central channel in which the valve sits. That central channel is the key to running tubeless tires. You’ll also notice that no such channel exists in the Mavic rim.

When mounting a tubeless tire, its important to make sure as much of the bead sits in that channel as possible before trying to push the last of the bead over the rim. That can be the difference between slipping the tire on with your fingers and using a tire lever to mount the rubber. This goes for both sides of the bead. Be patient and make sure the bead follows that channel faithfully.

I’ve encountered tires with a large enough inner diameter compared the the outer diameter of the rim that one side of the bead would slip off even as I was pushing the other side on. And any time I run into a rim with a reduced channel, I end up having trouble no matter what the tire is.

In removing a tire, it’s just as important to push both sides of the bead into the channel—all the way around—before attempting to remove the tire. This is the biggest single mistake I see people make. I’ve watched guys break tire levers when they failed to take this step. With mountain bike wheels and tires, as long as I take my time to push all of the bead into the gutter I am able to remove the tire without the need for a tire lever.

With wheels and tires meant for multi-surface road riding, all the same rules still apply, but I will say I run into challenging fits with greater frequency. That said, as long as the rim is properly taped, I haven’t had to use a tire lever to get a tire 35mm wide or larger on or off a rim. Which brings me to the subject of taping.

When taping up a wheel for the first time, you’ve got to respect that trough. Make sure the tape follows every contour of the rim as faithfully as possible. I was standing in a friend’s shop on an occasion when a customer came in with a wheel set he was unable to mount tires on. It turns out he hadn’t pressed the tape into that recess and the extra four or five millimeters of fit made it impossible for him to get the tire on. Even after re-taping it was a reasonably tight fit.

Regarding the subject of tape, I always tape my rims with two layers. A second layer doesn’t weigh much and it can make a difference in how quickly the tires hold air. I don’t want to put six ounces of sealant in the tires. I go slowly as I wrap and I’m careful to make sure not to get any folds in the tape or allow the tape to run up the side of the rim where it can interfere with the seal between the bead and hook.

Finally, I know some of you are wondering about the pure road application of tubeless, especially with tires of 23 or 25mm width. I’m not running any wheelsets this way. I’ve twice set up tires and wheels only to have the tire blow off the rim around 60 psi. It sounds like a gun shot and the resulting spray of sealant can take a half hour to clean up. I recommend getting your clothes in the washer immediately. On top of that, none of the road rims I’ve used so far have had a deep enough trough that I’ve been able to mount the tires without at least one, if not two, tire levers. When I’ve ridden road wheelsets set up by someone else, I haven’t felt the heavier tire and lower pressure resulted in a ride superior to an open tubular with a light tube.

I’m sold on tubeless for mountain bikes and multi-surface road bikes; that one change in technology could improve rolling resistance and traction while also eliminating pinch flats almost seems too good to be true. Almost. It is true.

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23 comments

  1. EMIL

    My tip for tubless mounting-soapy water. It really helps the tire slip into place. I routinely ride dedicated road tubless and wholeheartedly recommend it, never a problem with “blow off”.

    1. JL-Philly

      I always struggled with mounting until I was shown this trick as well! So I second Emil’s suggestion.

  2. JG

    I have been riding/racing road tubeless for a couple years now and can wholeheartedly recommend it. I like the comfort and reduced rolling resistance, as well as the fact that minor punctures seal up quickly. I usually don’t even notice the puncture until I get home and notice I’m down 10-15 psi. I’ve set up multiple rims tubeless, including Campy Shamal 2-way fit and Pacenti SL25 rims. The instructions in this article are key–there must be a deep enough trough and both sides of the bead need to be in it. With that technique, I can mount my Schwalbe Pro Ones without a tire lever at all. I’ve heard that the soapy water trick works well too.

    1. Dale

      Hasn’t been a problem for me and I’ve been running tubeless on mbt and on by B cross bike. I’d be more worried about a soap film leading to the tire blowing off. Never heard of that happening but with the alcohol it flashes off and is gone.

  3. Shuji Sakai

    I’m also a big fan of tubeless. My road, mountain, and track bike all run tubeless clinchers.

    Regarding the pure road use of tubeless: were your explosive experiences with tires and rims that met UST specs? The squared-off shape of the tire bead and the heavier construction of a road tubeless tire that meets UST spec is very robust.

    700c and 29’er rims might share the same effective diameter, but the ones designed for mountain bike use cap out at a maximum tire pressure rating around 40 PSI or thereabouts. A true road-use tubeless rim will state a much higher rating north of 100 PSI – see tubeless 700c rims from Shimano, DT Swiss and Mavic as examples of that.

    True UST rims also have no spoke holes drilled through them, which eliminates the need to tape the rim. The spokes nipples screw into threaded inserts on the inner diameter of the rim instead. UST rims are more expensive to make and is one of the reasons why nobody bought them. But taped-sealed road rim designs are catching up in terms of reliability at high pressure, and this will lower costs considerably.

    A UST tire will hold air for days without any sealant. I’ve used Hutchinsons in 23c and 25c at 80 – 90PSI without issue because they’re designed to run 100+ PSI when paired with a rim also designed for it.

    A “tubeless-ready” tire typically uses a lighter casing that weeps air faster (like latex tubes vs. butyl) and therefore requires a sealant to be used. Again, these are getting better and catching up in terms of reliability with the UST-spec tires.

    Myself, I’m willing to use a tape-sealed road tubeless rim from a reliable manufacturer if they say it’s ok to run 100+ PSI. I’m not so willing to play with “tubeless ready” tires at high pressures, though.

  4. Dave King

    Agreed on all of the above. I will never go back to tubes for my MTB. For reasons of traction and avoidance of flats. I no longer even think about goat head thorns, which is a game changer in some areas.

    I’ve never had difficulty removing tires and found installing and seating the tires a lot simpler with either an air compressor or a pump like the Bontrager Flashcharger (there are some other brands out there, too). It does matter the tire and rim combo. When I looked at Stan’s wheels a couple of years back, I believe they recommended not using WTB tires.

    You can also use a tubeless tire specific tire lever like the Kool stop tire bead jack which helps seat a tire more easily.

    I’ve ridden Hutchinson tubeless tires on tubeless Shimano Ultegra wheels. While I didn’t notice much different ride quality, I found that it was easy to remove, install and seat Hutchinson tires. Even with a regular floor pump. As EMIL says above, soapy water helps.

    A word of caution with road tubeless: you can’t set up regular road rims with tape to make them tubeless like you can with mtb rims. The high pressure of road tires almost invariably blows the tire off, which may happen on your garage floor or careening down a hill at 40 mph (ouch).

  5. MattC

    Been running mtb tubeless for ages. Have had exactly ONE flat in all these years (never did figure out why…no cut, couldn’t find anything wrong w/ the tire, it must have been the valve stem…but that’s why I still carry a tube in my pack…just in case). When I hang my mtb on the garage wall after a ride, by the next day I can see all the ‘flats’ I would have had…between the front and rear tires there are literally dozens of small white donuts of sealant visible on the dusty tires (I run Stans). Each one of those would have been a flat out on the trail somewhere. The only problem I have ever had is getting a new tire to ‘totally’ seat/seal so it doesn’t leak air and sealant overnight. Once I get that done right I can go weeks w/out adding air. Tho I don’t know that I’d ever give up my dropper post…I’m kind’ attached to that in a BIG way!

  6. Andrew

    Recent convert. Industry 9 tubeless ready wheelsets on my road and gravel bike, running Schwalbe tubeless 28s and 38s. I struggled a bit at first getting the seal etc, but I have learned a lot of tricks quickly and now it is easy. Recently set up some older non tubeless rims to work with Schwalbe 30s- as you say, getting the taping done properly was the absolute key. I love tubeless and really would never go back, on the road or on gravel. Seeing the flats you avoided on the tire is just magic.

  7. Rowan

    Totally agree on the benefits of tubeless but interesting detail you have where you say “careful to make sure not to get any folds in the tape or allow the tape to run up the side of the rim where it can interfere with the seal between the bead and hook.” My understanding is, and from fitting a few dozen tubeless tires is the tape IS supposed to run up the side of the rim and end just below the hook but where the tire bead sits. That way the rubber tire bead seals on the tape. This gives only two edges the sealant has to seal (the tire bead over the tape on each side of the tire) . If the tape stops short of the rubber bead the sealant has to seal 4 edges, the tire to the rim and the rim tape to the rim on both sides. This is where a lot of installations fail and the sealant never really seals the rim tape to the rim and it leaks into the rim cavity. I know that Stan’s recommends this method but if using other tapes that might not be so.
    Enjoy your blog by the way.


    1. Author
      Padraig

      To clarify: Yes, you want the tire to overlap slightly with the tape so that, as you mention, there are only two edges to seal, but you don’t want the tape running all the way to the hook so that it decreases the amount of hook the tire’s bead can grab. With most tire/rim combinations I’ve encountered the tape doesn’t need to extend much beyond the curve in the rim.

  8. Kyle

    I second the Hutchinson comment. I use their new Fusion 5 Performance Tubeless Ready tires on my road tubeless setup. The tubeless ready doesn’t have the butyl lining (so it requires Sealant) and thus doesn’t suffer the usual weight penalty. I was able to hand mount them without a fight or soap on Boyd Altamont rims. I was also able to pump them up with a normal floor pump (JoeBlow sport).

    It was my second time setting up tubeless, but it literally ticked all the boxes you stayed above (deep channel, double taped, etc), plus I did use Boyd’s valves which have a wing nut that makes tightening and loosening easier. The one lesson I did learn was to run a tube overnight to really set that tape in place. I didn’t at first, and had some slow leaks.

    I was running Vitoria Corsa G+ and S-works Turbos with latex tubes, so I didn’t think I’d notice too much difference. Rolling in a straight line I don’t, but cornering and rough terrain that slightly lower psi and the tubeless sidewalk have made cornering notably more confident for me. I don’t mind running tubes, but I quite enjoy this setup.

    If I had to fight with tires on the rims or tightening the valves it wouldn’t be worth the faff, but this was simple.

    Side note, the first time I setup tubeless was CX on a Stans 340. That sucked, tire blew off once and burped three times in races. That’s when I read that people had similar issues with tire retention.

  9. Dustin @ Southern Wheelworks

    Ive been riding tubeless for a decade now, and all of my bikes are set up tubeless, even the roadie with aero carbon wheels.

    Using a tire lever to get the tire on/off shouldn’t stop you from using tubeless. It’s not difficult to do.

    Tape – here’s a how-to I wrote a while back for how to properly tape a rim. Done right it’ll last for years and be very reliable. https://www.velocipedesalon.com/forum/f40/how-tubeless-rim-tape-install-45115.html

    The Schwalbe Pro One’s are fantastic tubeless road tires, they’re lighter and better riding than previous gen road tubeless tires. There are few tires with less rolling resistance :: http://www.bicyclerollingresistance.com/road-bike-reviews/schwalbe-pro-one-tubeless-2016

  10. Dustin @ Southern Wheelworks

    Padraig, I’m curious, what road tire/wheel/rim combinations have you had blow offs with?

    As for difficulty mounting tires, needing to use a tire lever has never been a deal breaker for me. I mean, it’s necessary with lots of tubed set ups too, and most of the MTB tubeless set ups I’ve done as well. All of the modern rims available for custom builds have good deep center channels. HED Belgium Plus, Boyd Altamonts and their carbon rims, Nox carbon rims, Pacenti, Stan’s, DT Swiss, you name it. I don’t have any first hand experience setting up a Shimano road wheel, but I recently fit a tubeless Hutchinson onto a Campy 2-Way Fit rim and it was a bit more trouble than most, but I still only needed one tire lever.

    One thing you didn’t mention in the article (or I missed it) that’s really important, especially with road/gravel/CX set ups, is to ONLY use tires designed for tubeless. If you try and set up a non-tubeless tire without a tube it WILL blow off. The good news here is there’s lots of great tubeless tires these days.

    And while some people report success installing tubeless tires onto non-tubeless rims, for road/gravel/CX I do not recommend this. The consequences of a blow off are too high. And, most non-tubeless rims have a U-shaped bead seat, there are no bead shelves like with a tubeless rim. Those bead shelves will hold the tire in place even if you do flat. I cut a tubeless Hutchinson Sector at about 35mph on a steep chunky gravel descent, and it took me a little while to get the bike stopped (both rims were HOT once I did get stopped), but the tire stayed locked in place and I was able to safely come to a stop. With a non-tubeless rim you’re much more likely for the tire to come off the rim if you flat.


  11. Author
    Padraig

    Everyone: Thanks for your comments and sharing your perspective. I continue to hear great things about Schwalbe and Hutchinson and hope to have a chance to review those at some point; my current backlog of tires for review is embarrassing.

    To those who asked which tire/rim combinations blew off: I really don’t want to get into that. I was using tubeless rims and tires (and should add that I don’t endorse trying to run tires or rims that aren’t tubeless as part of a tubeless setup) and because I haven’t heard of recurring problems from others with these products I don’t consider my experience conclusive.

  12. Mike

    Been running tubeless road for 5+ years now. Hutch tires. Have gone to 28s on the road now for the comfort. Running 70 to 80 lbs. had issue recently with the valve stem pulling through the outside wall of Mavic taped rim. Had a 28 with 80 lbs. never had that happen before.

  13. Brian

    I’ve had little to no problems running Hutchinson tires ( both Intensive 25’s and Sector 28’s) on Easton Ea90 SL wheels. No tape needed. Hutch Protect’Air Sealant.
    I ridden them on mixed to not great suburban N.Y. roads with a rider weight of 210-230.

  14. Michael Hotten

    I have been running road tubeless off and on ever since Shimano and Hutchinson announced their partnership. Those early Hutches were a bear to mount, but things have gotten better. I have asked a number of tire and wheel companies why road tubeless has been slow to adapt. Too few tire choices that cost too much, hard to setup, messy roadside repairs and a lack of enthusiasm at the shop level are some of the reasons given. A couple years ago, Schwalbe took a hard look at the road tubeless segment and decided the benefits outweighed the negatives. RKP tested their star entry and here’s what we found: http://redkiteprayer.com/2015/12/schwalbe-pro-one-tubeless/

  15. Shawn

    I recently bought a set of tubeless compatible road wheels (HED) but am running them with tubes for now. I was amazed at how difficult it was to get the tires on. Is your advise similar when mounting with a tube, i.e. getting the bead in the central channel? Thanks.

  16. Winky

    I can’t imagine how it helps to have the bead that is already mounted also in the centre channel. It is connected to the troublesome bead by an arc of floppy tyre and thus can’t really influence the other bead much. How can its precise position matter? If anything, it taking up room in the channel may make it more difficult to get enough “slack” with the relevant bead.

  17. Winky

    I still don’t get road tubeless. I guess I’m a luddite, but it seems to solve problems I simply don’t have.

    1) Mucking around with goop
    2) “Stanimals” to deal with after time
    3) Tyre mounting issues
    4) Compatibility issues
    5) Little benefit in terms of flats (already very rare for me)
    6) Not compatible with CO2 (admittedly makes no difference to me as I use a pump)
    7) Corrosion at the valve stem reported
    8) Spraying white goo over yourself, your bike and poor person behind you when you slash a tyre
    9) No saving on spares that need carrying
    10) “Burping” tyres
    11) Special pumps or compressor used for “seating” tyres in some cases

    Putting a lightweight tube in my tyre seems pretty straight-forward in comparison.

    I know people claim rolling resistance, spin-up and road-feel benefits. I’d be absolutely astonished if I could detect any of this in a blind test.

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