New Technology
Tubeless wheels/tires
By Jon Sharp

Pinch flats are the bane of many racers and non-racers alike. A poorly planned landing or a sharp-edged rock in the trail can be enough to ruin a good ride or a great race. What are pinch flats, you ask? Well, they are the result of the inner-tube being pinched between the rim and some object in the trail (usually a sharp rock). The hole is usually small, but enough to stop you in your tracks and force you to fix the flat.

So, naturally, in their quest to perfect the bicycle wheel, Mavic steps into the scene. Mavic claims to be the inventor of the UST standard. Other manufacturers have designed similar tubeless systems, and Mavic doesn't claim to be the inventor of the idea, but Mavic has been the most successful with making it a standard and with passing detailed specifications on to tire manufacturers. Mavic's claim is that if you have a UST wheel (most likely made by Mavic) and a UST tire, you will have a tubeless system that works well together.

Given their important role in this innovation, I decided to test their least-expensive UST wheel offering, the CrossRoc UST wheel. One of the first tire manufacturers (along with Michelin) to license this technology was Hutchinson. Given their commitment to the UST standard with Mavic, I decided to test their Python tubeless tire.

Mavic Crossroc UST Disc
Hutchinson Python Tubeless

Mavic Crossroc UST Disc Wheelset
As with most of Mavic's wheels, the CrossRoc is both beautiful and functional. Because it is a disc wheel, the CrossRoc Disc has a crossed spoke lacing pattern both front and rear. To keep the weight down, the CrossRoc has only 24 spokes front and rear. For an inexpensive cross-country disc wheelset, the weight is better than average at 810g front and 1020g rear.

To accomplish the air-tight seal necessary, Mavic has produced a rim that has no spoke holes on the inside. To do this, there are special aluminum "spoke screws" that hold the brass nipples into the rim. There is also a special ridge to "lock" the tire bead into place and form an air-tight seal.

Because of the low spoke-count, I found that the CrossRocs weren't as stiff as many 32-spoke wheels. The difference was minor, however, for a 160lb rider like myself. Heavier riders, however, might want to be careful when making this purchase. Try out a pair first.

The wheel comes with a removable valve stem. I found out the hard way that in this case, removable is good. After I got a flat miles from my destination, I had to pull out that valve stem and put a regular inner-tube on the rim. More about that later.

If you are sold on tubeless technology, then stick with Mavic. Their UST standard ensures a great fit-an important factor when you're trying to keep air in. The MSRP is around $379 for the disc version. I feel that at that price, this wheel is well worth it. The CrossRoc took lots of abuse on some pretty rocky trails with nary a wobble or a ding to them. I'd say Mavic knew what they were doing when they built this wheel with only 24 spokes.

For more information, contact:
Mavic Sports Inc.
(978) 469-8401
www.mavic.com

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Hutchinson Python Tubeless Tires
The Python is a wide cross-country tire. It's listed as a 2.0, but it's more like a 2.15. The tread pattern is made up of many closely-spaced small knobs. This makes it a great tire for hardpack, gravel, or rock, but not so good for mud. If you ride a lot in the mud, then you should go for the Mosquito tubeless. The python also has a very rounded profile, which makes cornering a smooth transition.

Mounting the tire wasn't difficult, once I got the hang of it. At first, though, the tire was quite difficult to mount-not because the bead was tight on the rim, but because it was difficult to get it to hold air. My problem was that I didn't use a sufficient amount of soapy water on the tire and rim. After LIBERALLY applying said soapy water, it held air. One thing I noticed about the tire is a small line that goes all the way around on the sidewall. This is your gage to see if the tire bead is properly seated in the rim. As per the instructions, there was an audible popping sound as the tire got hooked into its proper place on the rim.

I found that I needed to inflate the tire to very high pressures (at least 60 or 70psi) to get the tire to lock into place. Once locked into place, the tire can be deflated or inflated to a lower pressure. The tire sealed well with the rim, and there was only a minor loss of pressure between rides. After two or three days I had to add a little pressure to the tires.

I found out the hard way that there is a limit to how low of a pressure you can run. On a particularly muddy ride in Oregon, I had the tire pressure pretty low so as to glean as much traction as I could in those sloppy conditions. While rounding a tight switchback, my front tire rolled enough to allow mud and other debris to work between the tire and the rim. This halted me in my tracks. After trying in vain to get a good seal on the rim again (using a nearby stream instead of a bucket of soapy water), I gave up and put in a conventional tube.

This appears to be the biggest fault with the tubeless system: repairing flats. While my flat was caused by running extremely low pressures (around 15 or 16 psi), any thorn or nail that could puncture a tire with-tube, could puncture a tubeless tire. I have taken to riding with two spare tubes because of the difficulty of, after patching the tire, getting the tire to lock back in the rim on the trail.

All in all, I would recommend the Python (tubeless or otherwise) to any rider who rides in dry, hardpack conditions. The Python is a fast rolling tire that hooks up well in hard conditions. Its larger air volume makes it more comfortable and allows you to run lower psi whether it be of the tubeless variety or not.

For more information, contact:
Hutchinson USA
(888) 664-8824
www.hutchinsonrubber.com/tiresweb

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Summary: So, now that you understand a little more about tubeless and have seen some good products, you wonder if it is right for you. If you ride on trails with lots of thorns, consider this: Do you primarily get pinch flats or puncture flats? If you mostly get pinch flats, tubeless could be the thing for you. Many trails have no risk of puncture, only the occasional pinch flat. If that is the case, take a look at tubeless. If punctures are your bane, think twice before going to tubeless.

That said, I found that I could ride lower pressures and gain more traction and comfort on the trail with the combination of products tested here. I was amazed at how a particularly rocky trail that would normally slow me down for fear of flatting, had no impact on me because of the pinch-flat protection afforded by this technology. If you do go tubeless, take a look at the Mavic CrossRoc and the Hutchinson Python Tubeless. This combination (when inflated proerly) worked well and held up well to more abuse than I typically give tires and wheels.

Jon Sharp is a Contributing Editor to GearReview.com specializing in mountain biking.