Dual-chamber mountain bike tire takes on the snake bites and the burps
By Ben Coxworth
February 11, 2014
So, you've upgraded your mountain bike's clincher tires to tubeless, and now you figure you're all up-to-date and on the cutting edge, right? Well, perhaps not for much longer. German tire-maker Schwalbe and bike parts manufacturer Syntace have developed a tubeless dual-chamber tire and wheel system, that they claim should offer better performance than your current old-school single-chamber tires.
First of all, for people unfamiliar with the advantages of conventional tubeless mountain bike tires, here are a few of the main ones – they're light, as no inner tube is required; they provide better handling, since there isn't an outer tire and an inner tube sliding against one another; they're self-sealing, if sealant is being used; and, because there's no tube to protect, they can be run at lower pressure for increased traction.
As far as that last point goes, however, even tubeless tires can still get "snake bite" pinch flats if the air pressure is too low. They can also pop off the rim when taking big hits, in a process known as "burping." That's where the new Schwalbe/Syntace system comes in.
It incorporates a higher-pressure inner air chamber, and a lower-pressure outer chamber. The inner one provides a firm cushion that helps stop the tire from striking the rim, lessening the likelihood of snake bite flats, plus it secures the tire bead more securely on the rim, making burps less likely. This means that the outer chamber can be run at pressures as low as 14 psi (1 bar) for much better traction – most conventional tubeless tires shouldn't be run lower than about 20 psi, depending on the weight of the rider.
As an added side benefit, if the outer chamber is punctured and won't seal, the air in the inner chamber will allow the bike to temporarily still be rideable.
Schwalbe and Syntace were initially working independently on separate projects, but decided to pool their resources when they discovered their common interest. The commercial version of the system should reportedly weigh under 200 grams (7 oz) and be compatible with existing rims and tires – although a second valve stem hole will presumably have to be drilled in the rim.
It's scheduled to be unveiled in August at the Eurobike trade show.