First Ride: Schwalbe Launches Double Chamber Tire System

Tire manufacturer Schwalbe has teamed up with German component maker Syntace to produce a double chamber tire system that is said to increase traction while decreasing the risk of punctures. Historically it's a claim that's been too good to be true, but in two days of testing with Switch-Backs.com around Malaga in Southern Spain, we were unable to cause a flat that would end a race run. Precise details are still to be released, but here is what we know so far...



Two Chambers?

Schwalbe and Syntace are pooling their know-how to develop what could be a revolutionary idea for mountain bikers. With a double chamber system, it will be possible to ride with very low air pressures and, consequently, to improve tire performance enormously. Initially, Schwalbe and Syntace had the same idea independently of each other. Now, the two companies have decided to join forces and further develop the system together.

Why go to the trouble of creating a two chamber design? “With low air pressure, off-road tire performance improves - the tires can adapt better to the terrain and react far more sensitively,'' Schwalbe told us. ''They roll more easily over uneven ground and provide more grip and control. But one can hardly risk riding on standard MTB tires with less than 1.5 bar, because the risk of pinch flats is simply too great with the current trend towards wide rims, the performance of tires with low air pressure is considerably better and less spongy. The risk of pinch flats, however, remains the same.” And this is where the double chamber system looks to leap ahead of standard technology that we're all used to seeing. “The solution is a double chamber system,'' they explained to us. ''There is a further air chamber inside the visible tire. This inner chamber is filled with high air pressure and effectively prevents the tire hitting the edge of the rim. At the same time, the inner system secures the tire on the rim and prevents burping, a loss of air of the tubeless system in the case of low pressure. Depending on the situation, the air pressure in the outer chamber can now be reduced down to 1bar without running any risk.''



What's Inside?

So, what exactly does this double chamber system look like? Despite the intentionally vague description by Schwalbe, we're not quite sure yet, and we were kept pretty much in the dark before the first ride as to what we were even there for. That there were two valves into the rim was obvious, but beyond that... What we were told is that it isn't the kind of system many downhill teams use with a tube inside a sealed tubeless system that acts as a back up if the tube pinches; we were told it was about performance, about tuning the spring curve of the tire; we were told that when Michael Kull, Schwalbe's marketing and race support guy, tested the system for a week on the Canary Island of La Palma's notoriously rocky, high impact trails, he was unable to puncture.

When will it be available? We'll find out during the 2014 Eurobike trade show, during which we'll be able to present precise information regarding design and prices. Schwalbe says that they will be responsible for the production and marketing of the system, and it is expected to be compatible with conventional tires and rims while weighing less than 200 grams.



Schwalbe is making some big claims of the new dual chamber system, and it's obvious that they've been quite happy with its performance during the development phase. They told us that all of the testers involved have been thrilled about the possibilities that the design presents:

• With 14.5 psi / 1bar, the tire grip is gigantic. The contact surface is very large and the tires seldom, if ever, slide on loose ground. Even on the roughest terrain, the tires literally stick to the ground.

• The tire is the most sensitive cushioning element on the bike. The extra cushioning and traction in the case of low air pressure lead to much better control over the bike and allow distinctly higher speeds.

• And all this without the risk of pinch flats. Dented rims are also a thing of the past. Consequently, much lighter tires can be used even for the toughest conditions. What is more, the additional air chamber has excellent emergency running characteristics.



On the Trail

This last week Schwalbe pulled together something more like an informal gathering of the bike press than a full on product launch: there were no powerpoint presentations, no goodie bags and no thumb drives loaded with product imagery - just good old fashioned shuttling on some of Europe's best winter trails.

We started riding on day one with 1.9 bar in our tires front and rear. That's 27.5 psi, so about what I would expect to inflate a tubeless tire to for a day of shuttling. The first couple of runs were fun, the tires felt good and no-one flatted, despite the rock-strewn track we were riding. After two runs the Schwalbe engineers dropped the pressure to 1.2 bar front, 1.4 bar rear, which works out as 17 and 20 psi. Chances are, you'd never run that low of pressure on purpose in a traditional system, even with the thickest casings you could find - the tire would roll from side to side, and the risk of pinching or burping would be too great. With Schwalbe's new system, it didn't feel particularly strange, and in fact the first place I really noticed it was under heavy braking - the extra traction you gain when the tire is able to spread wide across the trail and doesn't skip over bumps meant rethinking the braking points I'd worked out on my first two runs.



Through flat corners the lower pressure felt good, but pushing through sandy ruts felt strange - the tire felt like it wanted to catch the edge more than it did at a higher pressure. It's safe to say, though, that having flown in from a particularly wet British winter, dry, sandy ruts aren't something I've ridden much recently, so this could well be something you'd work around.

So, were there any troubles during the two days we spent riding the double chamber system? On my third run on the lower pressure, I hit a rock really hard and felt the rear suspension bottom in a way you'd normally associate with a pinch flat. I pumped through the next couple of compressions and was surprised to find the tire holding pressure. At the bottom of the trail, I gave the rear tire the thumb test and found it considerably harder than the front - something had happened when I hit the rock, but the tire hadn't flatted, and if anything, it had gained pressure. I pushed the Schwalbe representatives over lunch to find out what had happened but they remained tight-lipped. On day two, Markus Hachmeyer, Schwalbe's Senior Product Manager, told me that the inner chamber had been incorrectly seated and the impact had forced air from that high pressure chamber into the low pressure main chamber. If this was a race run, I'd have been pretty happy to finish with an extra 10 psi more in my tire at the finish line rather than a flat thanks to an impact like that. This also shows that, just like with a standard tube or tubeless layout, proper setup is key.

Despite a distinct lack of details, it seems the system provides many of the benefits of a lower volume tire - more stability at low pressures, more small bump compliance thanks to the lower pressure - with the advantages of a larger volume tire, like the reduced risk of a pinch flat and a broader contact patch. Even if you do flat the outer chamber, the inner chamber, which occupies a much smaller volume that a traditional inner tube, will retain high pressure and allow the rider to finish their run with the tire firmly secured to the rim.




Pinkbike's take:
www.schwalbe.com
www.syntace.com

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