Fun With Tubeless Road Tires [updated 9/10]

Schwalbe Pro One tire
Schwalbe Pro One, 700×28, on Hed Belgium Plus rim

Last September I got a new tubeless wheelset for my road bike. This is a report on my experience for those of you who have been mesmerized by all the current hype on tubeless road wheels yet are not ready to make the leap. The bottom line is: it’s been a mixed bag—some good, some not so good.

For those of you who either don’t mountain bike or have been emulating Rip Van Winkle, tubeless tires are clincher tires that do not require an inner tube. Tubeless tires are somewhat common on mountain bikes mainly because they allow you to use lower tire pressures without risking ‘snake bite’ or pinch flats. With tire pressures regularly below 35 psi and terrain rough and rocky terrain, the odds of flatting when mountain biking are higher. Tubeless tires mitigate if not eliminate pinch flats entirely. Now they’re migrating to road wheels.

Tubeless tires are usually set up with sealant in lieu of inner tubes. There are many brands of sealant, the most well-known of which is Stan’s NoTubes. Sealants are usually liquid latex with particles. When you get a puncture, sealant flows to the cut and coagulates to seal it up. Depending on how large the cut is, the sealant may or may not be able to close the cut: the larger the cut, the less likely success. You can set up tubeless tires without sealant but then you forego the convenience of punctures self-sealing.

True tubeless rims and tires are designed differently from regular clinchers. The main difference is that tubeless rims have a different inner rim shape in order to lock the tire bead in place. Tubeless tires have tighter beads (or at least less variation in bead diameter), a coating to help keep air in, and often a particular bead shape to better ‘lock’ to the rim. It is possible to use regular rims and tires without tubes but the chance of success are hit and miss. I won’t go into that; I’ll merely say that mine were dedicated tubeless tires and rims.

Why would you want to use tubeless wheels on a road bike? That’s a good question. The hype is that road tubeless tires: (1) reduce flats, (2) allow you to ride when you do get a puncture, (3) roll faster and “feel just like riding a sew-up!” However you almost never hear about what hassles tubeless tires cause yet we know that there is almost nothing in life that is a perfect net gain—everything has a down side.

Before I get into my experience, here is the set-up I had. The rims were HED Belgium C2 rims and Schwalbe Pro One tires. (These rims are wonderful—I have those same rims on another bike that is set up traditionally with inner tubes.) They are light, seem to be strong (I haven’t dented them yet), and are wide thus increasing the tire’s volume. I had never used Schwalbe tires before let alone Schwalbe Pro One tires but they have an excellent reputation. I have no other experience on dedicated tubeless road tires with which to compare them. The rims were taped with Stan’s tape and set up with Stan’s sealant. The Schwalbe tires were nominal 28 mm in width. But on the wide HED rims they balloon out and measure out about 30 mm thus providing a cushier ride. I inflate them to 50 psi front/60psi rear, which is close to Frank Berto’s guidelines, although I have also experimented with lower and higher pressures. I’ve put about 1,900 miles on them since last year, riding them mostly on pavement but also on fire roads.

I’ve inspected each tire after practically every ride in order to detect any foreign objects embedded in the tire because with sealant it is possible to have a puncture and not know it at all if the sealant is able to seal it quickly, most likely with pinhole type punctures rather than cuts. I finally incurred my first puncture a few weeks ago, on the rear tire. Oddly it was a cut less than 1 mm and there was no sealant leaking out and no foreign object embedded. The tire pressure was about 25 psi. I pumped it up to 60 psi and it seemed to hold, but during the subsequent ride it deflated again to about 25 psi. Because I didn’t see any sealant exiting the cut, I presumed the problem was insufficient sealant. Sealants are water based and eventually dry up; I had checked my tires over the previous nine months and they always seemed to be fine. So the next step was to add more sealant. I added roughly one more ounce of Stan’s to the tire, rotated it to spread the sealant around and then pumped it up. Immediately sealant started to ooze out of the small cut. Eventually it stopped around 45 psi. I left it overnight and it seemed to be okay, so I pumped it up again to 60 psi. No leakage. So I went for a ride and halfway through the ride noticed that the tire was soft. Looking at the tire I could see I had sealant sprayed all over the back of the seat tube, the chainstays, and the saddle bag. Also there was a noticeable patch of flattened, semi-sticky sealant around the cut area. Pumping up the tire seemed to work but later down the road the tire softened and I had more spray and gunk on my bike and tire. When I got home the pressure was about 35 psi. That incident highlights some of the problems with tubeless road tires. First, since the tire pressure in road bikes is quite high compared to mountain bike tires, it’s a much harder job for sealant to seal a puncture even one as small as one millimeter (which is supposed to be possible with Stan’s). And Stan’s is the most popular and supposedly a very reliable brand. Second, the degree of sealing isn’t all or nothing but variable. The first time I was riding on about 25 psi; the second time about 35 psi. During the day as the temperature of the tire increases with the ambient environment and with friction, the pressure goes up. Also, as you ride the tire flexes. Both seem to affect how good a seal you achieve. Since I’m pretty light and I was aware of the low pressure, I was able to ride very carefully over bumps to avoid bottoming out the tire and getting a pinch flat. But I was paranoid the entire time.

The Stan’s sealant just wasn’t working. So I took the tire off and cleaned out all the sealant and put in other brand, Orange Seal, which is supposed to close up bigger punctures.

Before I get to the rest of my story, let me digress slightly about removing a tubeless tire: it can be a lot harder than a regular clincher because the tire beads are more inflexible. I tried putting both beads in the wheel well to create ‘slack’ and that didn’t work. I had to use tire irons to get the damn thing off. Try doing that by the side of the road without getting covered in sealant! The other hassle is that airing up a tubeless tire can be impossible with a regular floor pump let alone a hand pump; you just can’t pump enough air in fast enough to blow the beads against the rim wall to seal. Fortunately I was doing this in the shop and not out on the road, and I happen to have an air compressor that was able to do the job. If you flat a tubeless tire when you are out riding and the sealant doesn’t work, then you’re going to have to put in an inner tube to get home, which means you have to remove the tire. But you’re not going to have an air compressor when you’re out riding. You can try a CO2 cartridge to blast the beads in place. However CO2 is not recommended for tires with sealant because the rapid cooling induced by the CO2 sets off a chain reaction that turns solidified the latex in the sealant. If you’re putting a tube in, then this is irrelevant.

Back to my story: once the tire was pressurized to 60 psi, sealant began bubbling out of the cut. Eventually it stopped. I let it sit overnight, pumped it back to 60 psi the next morning and no sealant leak. Apparently Orange Seal worked. I’ve been riding that tire since on asphalt and dirt and it’s holding air fine.

Moral of the story:

  • Tubeless tires may save you the hassle of an occasional flat. But when you do get a flat it can be more hassle than using inner tubes. First, if you’re using sealant, you and your bike are probably going to be sprayed with sealant. Fortunately sealant dries and you can remove it easily; including rubber gloves and some paper towels in your repair kit is advised. Second, getting a tubeless tire off of a rim is harder and sometimes near impossible. Not good if you need to insert an inner tube by the side of the road. Third, sealant may seal a cut but you may not be able to run your regular pressure. With a soft tire you need to ride carefully especially when you corner or go over bumps. Note that by road standards I run pretty low pressure already—45 to 60 psi. Higher pressures make it even harder for sealant to work. If you regularly run 90+ psi, sealant may not work except for the smallest of punctures. (There is another danger of completely blowing a tubeless tire off the rim at those pressures.)
  • Regarding ride quality I was disappointed to find that it was just so-so. As I mentioned, I have another Hed Belgium+ wheelset on another bike but it has Michelin Pro4 Service Course tires, 700×25, with latex inner tubes. The 25 mm Michelins balloon out to 30 mm (!) on the Hed rims, so they are the same width as the Schwalbe tires. (I’ve found Michelin tires to run wider than they are specced even on regular rims.) The Michelins have a deliriously smooth ride that are so close to that of high quality sew-ups. So the difference must be in the Schwalbe tire casings. I am guessing that in order to beef up the casing for tubeless use Schwalbe compromised their tires’ suppleness. Or, it could just be that Michelin makes better casings than Schwalbe. I’m not saying the ride quality of the tubeless Schwalbe is bad, just that it wasn’t as good as the hype would make it be!
  • I’m going to continue to run tubeless tires for a while as an experiment. It’s too early to say that they really reduce the number of flats I get, as I just don’t see any other cuts or punctures in the tires that were sealed by the Stan’s. We shall see. With only so-so ride quality I’m inclined to swap these out for Michelins with latex tubes at some point. Inner tubes may be an inconvenience but they will get you home albeit later than you had planned; with tubeless tires and sealant you may fewer flats, but you could be in world of trouble if you do get one out on the road.

UPDATE 9/10: Well, I had a second flat a few days ago, merely weeks after the first one. This was also in the rear tire, a 2mm cut off-center. I was immediately aware of it, hearing the swish-swish-swish of leaking air. It also stopped! The Orange sealant was able to stop the leak at about 25-30 psi. I tried pumping more air in and sealant just oozed out. So I rode it about five miles more and checked again: no leak and instead of having an oozing sore on the tire I now had an odd looking ‘scab’–more of a dried plug. I pumped up the tire to 60 psi and it held! No problems since then. I conclude that for a 2 mm cut Orange Seal does indeed work but not immediately. It needs time to flow to the site, set up, and dry. In the meantime you’re stuck riding on a road tire at very low pressure. Or you could take a nice break. Although moderately convenient (after all, I was able to keep riding albeit carefully), it wouldn’t have been a hassle just to change an inner tube and pump it up to the correct pressure. Of course I don’t have to deal with patching an inner tube, so that counts for something.