Cycling is undergoing a transformation right before our eyes, as technology cycles quicken, and new gear such as 1 x 11 and disc brakes become industry standard. So too with tires.  Until recent years, one could only choose from traditional clincher tires with tubes, or glued on “sew up” or tubular tires.   In the early 90s when I began racing, we trained on clinchers but nearly everyone raced on tubulars. Because tubulars were lighter, rolled better, cornered better and they also provided a much more supple ride on rough pavement.   These days almost no one rides tubular road wheels for training- they are too expensive to replace if you flat, and the modern clincher tires offer pretty good performance. Many time trialists still prefer tubulars and of course pro racers still ride them.

For cyclocross the benefits of tubulars were always clear: tubular wheels are lighter than a clincher rim, and the tires are lighter than a clincher tire. But the real advantage is that due to the different rim profile you won’t pinch flat a tubular when you hit a rock or tree root, and thus you can run a tubular tires at much lower pressure than a clincher.

Enter tubeless: it is still a clincher rim, but now there is no tube to pinch flat. So you can in theory run lower pressure in a tubeless tire vs. the equivalent clincher tire with a tube. While the marketing folks may try and say “it’s just as good as a tubular,” that is really not true in several respects. I would say tubeless is better in some ways, but inferior in other ways.  For example, while there is no tube to pinch flat, if you run too low a pressure you can “burp” a tire. What is burping? When you go over a rock or root and the bead of the tire transiently separates from the rim, air can escape. Once that happens, the pressure falls lower and then there is more chance you will be riding or running to the pit for a wheel change.

I discovered this in my first race this season, when I pre-rode the course the first time with no issues, but 45 min. later, on my 2nd pre-ride I noticed my rear wheel was bottoming out. Halfway through the lap I jumped out of the course and started walking back towards our team tent. Luckily a guy had a pump in the back of a nearby car and helped me out. He said that I’d better put air in the tire, because once it goes too low the bead will separate from the rim and then you won’t get it re-seated without an air compressor. I don’t know about you, but I don’t often travel to races with a compressor.

I pumped the tire to 40 psi, and let it stand for 30 min while I was warming up on the trainer and the tire maintained pressure.  I then dropped it down to about 32 lbs and raced on it. But I was hesitant to race on it at 25 lbs, which I could more than easily do with the tubulars I rode on the previous season.  So one consideration is that yes, you can run lower pressure, and you won’t pinch flat but there is still the risk of burping a tire and that simply doesn’t exist with tubulars.

The second inferiority is weight- tubeless tires employ a stiffer side wall than clinchers, therefore they are heavier than a standard clincher. The extra weight is not insignificant, probably 75-100 grams. Then you have to add sealant to a tubeless tire. In the end, a tubeless set up will be as heavy, if not heavier than a tubed clincher, and it will be significantly heavier than a tubular set up.  Remember again that a tubular rim does not need the extra flange strength to hold the bead, nor to hold the internal pressure. So a tubular rim is almost always lighter than a clincher rim.

One benefit of traditional clinchers is that you can quickly swap tires based on course conditions. This can be a 5-10 min. job the night before or morning of a race if you keep an extra set of tires with tubes ready.  But tubeless tires are more painstaking to mount on the rims, as the bead is a much tighter fit. Then you need a compressor, and you usually will need sealant. So don’t expect to be quickly swapping tires with a tubeless set up. It is more likely that you will end up with 2 or more wheel sets with tires mounted, the same as you would do with glued on tires. In the amateur ranks, I know some very successful racers who use predominantly one tire for all conditions, so maybe changing tires for different course conditions isn’t all that critical.

So with all that said, why I am racing on tubeless? The simple answer is that I’m not sponsored. If I were a pro rider like Jeremy Powers or Stephen Hyde and someone else was paying for my wheels and tires, then I would gladly run tubulars. Similarly those guys have team mechanics who enjoy sipping an IPA and breathing Clement glue under a full moon.  For the rest of us, we will just pedal a little bit harder and cross our fingers that we beat the race predictor.