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I received this question on December 24th via e-mail. What's your opinion on the tubeless trend? CR
KB's reply: I thought you'd never ask... Here are some rambling thoughts on the subject: Mavic's info: First of all, if you are curious, and to make sure this is even handed, here's the Mavic site URL http://www.mavic.com/eng/prod/fiche/cmax.htm for their views on the subject. They are revamping their website right now, so clicking on www.mavic.com and finding the link to the Crossmax UST area might be a better way to get this information after a little while. My initial thoughts on the design and engineering of UST wheels and tires: Given the problems they needed to solve, the UST wheels and tires are a very cool design. Mavic's technical and manufacturing folks really worked hard on this one and it shows. I have always respected their engineering, and I am not disappointed with these. They are a bit too complicated for my personal tastes, and there are certainly much simpler ways (and even a few more expensive ways) to reduce the tendency to pinch flat or to be able to ride with low pressure in your tires. But they look pretty good and, as ungodly expensive a they are, they aren't too far out there as very high end components go, based on what people seem to be willing to buy these days. Scary isn't it. The future for high performance tubeless bicycle wheels - a prediction: Even with Mavic's good execution in design and manufacturing, it isn't clear to me that the UST wheels and tubeless tires are a worthwhile advantage for that many riders. But they'll have to prove to be an obvious (and real!) advantage to the people using them in in the long run in order to catch on and stick, and then to grow as a product category and be less expensive. If they do succeed at all this it will not be because they are a new fad. Fads come and go quickly. If they last it will be because of one or more of the advantages they offer really matter; they have to deliver some advantage to the rider/customer. This might happen right away, but I think the current situation is not clear in that respect. It is more likely to happen as the wheels are improved in the future. As I see it, to succeed they need the following to happen: The UST tire and wheels are very difficult to pinch flat. That is a very definite advantage if that is a characteristic you need. Pro racers need this. That shouldn't be a big shock to anyone. Pros ride skinny tires on hard tail frames and go damn fast on a lot of different surfaces. They have to go absolutely as fast as possible over the bumps, and can't always pick careful lines in traffic. The situation is begging for pinch flats. If I were a pro and I wanted to be certain I finished a race on a rocky course, the Hutchinson UST tires would be a very good way to make sure of that. They are big, fat tires. But they are slow rollers too. I wouldn't use them unless I had to. Some recreational riders could use some pinch flat resistance too. If I lived in a very rocky area, I might be tempted to have a set of these around for "special occasions", rides where I really wanted to have the fastest bike I could have, and risking some expensive equipment was worth the gamble. I'd have to have the money to afford them in the first place of course. But I wouldn't use them for day to day riding. If I really needed the pinch flat resistance for that there are other ways to have it that are far less expensive and simpler, using existing equipment. of course, I could also ride a full suspension bike. They help out too. If the racers start riding full suspension bikes, and they are, things might change, pulling the rug out from under this thing. Racers have to sweat about weight and they are going to want to keep those full suspension bikes light. The extra 1/2 pound or so in the wheels will matter. My guess is that Mavic developed the USTs without light full suspension race bikes in mind or around much, and the tubeless option may be made obsolete, or at least less popular with the racers by that trend. It's tough in a fashion business. We'll see. If there weren't that many rocks where I rode and I could ride good lines around them or over them without spoiling all the fun, I'd pass on the tubeless stuff, and the other anti-pinch flat stuff too. It's good to learn to ride better, part of the challenge I like when I ride. Anti-pinch flat properties are clearly not a very important solution for a recreational rider who doesn't pinch flat often, or who is on a tight budget and can't afford them. This is the largest segment of riders by far, so there is a mismatch here for the majority of riders - a problem that doesn't need a solution. One more thing. Riding a set of wheels like this and taking advantage of the anti-pinch flat properties is a little more complicated than it seems too. If the rider rides as though rocks won't cause flats, and charges them with abandon, rims will be the next casualty. This comes up pretty quick out on the trail. The press is starting to report on this (Velonews, Mountain bike, and MTBR). The difference in impact between a pinched tube and a damaged rim is pretty small. If you increase pinch flat resistance and you don't increase the rim's resistance to impact damage there is a potentially expensive problem. Those UST rims or any other proprietary rims are not going to be cheap or easy to replace either. You can get some rim protection with larger tires,like the Hutchinsons. But that's not unique to tubeless systems, and it will slow you down even more on hard surfaces. Or you can develop an even trickier rim design. I don't see how this is going to be a big net advantage in the long run to a recreational rider. It's going to be difficult for them to develop the finesse to know just how hard you can slam a rock ledge and take advantage of the pinch flat resistance, but not to hard in order to avoid a rim ding. Heavy tires with deep tread blocks and thick base rubber help a little. But the weight of the tubeless set ups is already high, so this can only be done by compromising their desirability. 2) Low pressure riding performance Tires run at low pressure have great traction for climbing and descending. Tires are also part of the bike's suspension system, the most effective part for very small bumps. Softer tires conform to the small bumps more easily than harder tires. They save some energy when they do, so a bike will roll faster over the right kind of bumps with softer tires. That's the good part. There are lower limits to the tire's pressure when cornering and jumping though. I weigh 170 pounds, and I felt uncomfortable on the tires at 30 psi when turning hard in technical situations. They squirmed sideways. This is not new. We discovered it while riding the first cut down rims and came up with minimum pressures (not absolute, but good guidelines) to avoid it. Pressures in the high 30s to low 40s were best. The UST tires at 30 psi also rolled over pretty far laterally when I landed coming down off a ledge a little sideways. The tires didn't lose air, but the big lateral squirm or roll bothered me a bit. I might be able to adapt to it in time. I might manage to pull a bead off or fill the gap with dirt. This happens at 40 psi in bad situations. It just depends on how I land and what I hit when I do. Lighter riders would be less prone to the problems, though they would feel them if they rode more aggressively than I do, which is not that hard to do. Bigger riders will have more trouble. This has always been true though, it's one of the most important reasons why fat tires are so fun to ride. And, if you play around a little, you'll discover that fatter tires are more fun to ride at low pressure. They hook up noticeably better and ride smoother. They are just slow. One of my "coaching secrets" for beginning riders is to lose the skinny racing tires they get on their bikes and put some big knobbies on. They immediately can ride tricky technical stuff they couldn't ride before on the racing skins. And, the Hutchinson 2.0 UST tires are FAT tires. They are bigger than their older 2.0 tires and bigger than our 2.1 tires. I think that's what riders are feeling on a ride to a large extent. It is not a mystery that a tire this fat, run at low pressure, delivers a smooth ride, is less prone to pinch flats, and the traction makes you feel like a trials star or moto ace. It is also not a secret that they roll slowly on hard surfaces and weigh a lot. That is, they cost you power and speed in some situations - a lot of situations frankly. These traits have never been popular with skilled XC riders in the past, but they're wrapped up in a trendy new package that has everyone looking the other way this time. That will pass in time I think. And, a slower rolling high traction tire might not be a bad thing for recreational riders, for whom speed is less a concern than traction and forgiving performance in the rocky technical stuff is good. It comes back to this. There are a lot of ways to cook an egg. Who's to say which is the right way to do it? Both high pressure, faster rolling tires and lower pressure, sticky tires are interesting, and are fun to ride. But you can decide which is best on a given day, and the best on that day will depend on the trail conditions and rider's skills and goals. From a commercial POV It's not a simple call - hard to say if any will prevail. I feel that neither should. But I also think most riders won't need a tubeless wheel configuration to have a good range of performance and a fun time on the bike. 3) Ease of use and reliability I haven't ridden these long enough to know what will happen to them in the long run. I haven't had any problems with them so far. They are still true, which is good because I don't even have a spoke wrench for them. I have not gone out to see how hard I can bash rocks before I flat on them, or ding the rim. They are too expensive. I have done that on some of my rims and tires before, when we were messing around with padding tires to prevent pinch flats. It's not hard to do. I'm happy as long as I have a tube in my pack that I can install. I did notice that seating the UST bead properly out on the trail is a very good, and very necessary upper body workout with a mini pump, since it has to be inflated to a pressure over 50 psi to pop up onto the bead seat and leaks air freely if it's not seated completely. A bit scary, but not a killer problem if you are fit, and patient, and have some sunlight left. Here's a little basic information to make some of my views clear starting with some weight measurements I made recently. You can see that the tubeless wheel and tire assemblies are pretty heavy compared to the others in the mix of lightweight, expensive wheels, including ours and the regular Crossmax wheels. 360 grams is a big penalty to pay. If one were to get rigorous and calculate moments of inertia, the basic differences between the tubeless wheels and conventional wheels would be even greater. Keep in mind that I seldom advocate light wheels for use by recreational riders unless there is a good reason to use them, and there just aren't that many good reasons for recreational riders to use them. But, in spite of that, I think adding this much weight to a set of wheels has to be justified, even by my fairly pragmatic (some would say stodgy) standards. Within the range of UST tires available right now the Hutchinson tires I have are fairly light. I think some will be made lighter soon. A weight reduction will either affect the tire's leak down rate if side walls are made thinner, or it will affect the wheel's ability to be ridden at low pressure, if the casing size is made smaller, due to an increased tendency for the rim to be damaged from terrain impacts with a smaller tire. My feeling is that the tubeless wheel and tire will not be made lighter than a current light wheel, tire, and tube at a similar cost with current materials. My impressions from riding the UST wheels From the performance point of view, the benefits from pinch flat resistance and possibly from a little more supple tire in some types of terrain have to overcome the high rolling resistance and extra weight of the tires. That's the way it is here in Santa Cruz, and that's the way it is in a lot of places I've ridden. For me so far, this doesn't look like an advantage for the UST system. If I lived in Moab or some place where pinch flats were common, I might feel differently about it. If I made my living riding these things on a closed course, and the course was rough enough to benefit from the tires, and overcome their weight and sluggish rolling characteristics, I'd dig them - as long as someone else paid for them. I did get turned on to riding normal big, fat, puffy, forgiving tires with tubes again after trying the USTs. I had a set gathering dust in the garage and they aren't anymore. That's a plus, especially around here in winter. It worked out well on snow in Tahoe too. And I came up with another fun thing to try when you are bored and looking for a diversion. Right now, if they were my wheels and I was trying to make them work well, I'd run them up to the same pressure I use on conventional wheels now, 40 - 45 psi in the front and 45 - 50 psi in the back, unless I was racing in Moab, where I use 60 and 65 psi to avoid pinching in the fast rocky sections. I believe some of the fast racers are using normal pressures in UST tires too. For them, the advantage of the tubeless design is to add insurance, making it a little more probable that they finish the race without a flat. High pressure keeps them rolling faster on the hard sections, and that is a lot of the course in a lot of races. They might also add a little to their wallet using when they use the UST wheels and tires, with the pressure coming from sponsorship commitments rather than a Silca pump. Hard to say for sure. If I did decide to ride with tubeless wheels at normal pressure, I am not sure they would make a lot of sense for me anymore. I can get adequate anti-pinch flat performance with other less complicated, less expensive means, including riding good lines. And with conventional stuff, I have a very large selection of tires to choose from at good prices, anywhere in the world. Plus, if I do manage to nail my rim on a rock and ruin it, which happens to me a few times a year because I am clumsy, I can replace it a lot more easily and inexpensively with a conventional rim, and have a selection of rims to choose from for the replacement. Press coverage The wheels and tires seem to be getting strong support in the press. I don't know if each of the reviewers are only rating the performance of the wheels and tires though. They could also be fanning the embers of something they see as a potential new trend, commercially speaking. This would be tempting in a biz which is has been living fat off of big trends for quite a few years, and it's their job, so I am not blaming them for it. Trends are often created by the press, and that helps the business grow, and helps to sell magazines and ad space too. The biz and press are running a bit low on new things that are motivating people to spend $ these days, so everyone's looking for the next big thing. Aside from the difficulties of actually developing useful new bikes parts - which ain't easy - it's a tricky one for everyone involved. It will be hard to ever know, and it really doesn't matter that much in the long view of things. If the press and the industry pushes hard enough though, the stuff will catch on for a while. It has always worked that way in this situation. And, of course, I am always skeptical about these things. You should be too. KB
Fine print: The opinions expressed herein by Keith Bontrager are in the nature of general observations and should not be relied upon in your specific situation. Your question, problem, bicycle or component, may be different than the one he is discussing. This Page (Web Site) is not a repair manual and is not a substitute for having your bicycle examined and repaired by a qualified bicycle mechanic. It is not intended as a tutorial or course in how to safely ride or use your bicycle. See your local library or bicycle store for publications regarding how to ride and repair your bicycle. Think of Keith like your Aunt Edna. You wouldn't really do what she tells you to do, now would you? Bontrager Cycles is a division of Trek Bicycle Corporation. Bontrager and Trek are registered Trademarks of Trek Bicycle Corporation. Copyright, Trek Bicycle Corporation. All rights reserved.
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