Back in February, we heard about a prototype Schwalbe mountain bike tyre system that used a dual-chamber setup to both increase traction and minimize flats. The design has since been refined, and the commercial version of the product was officially unveiled last month. It’s called Procore, and we had a chance to see how it works at Interbike 2014.
First of all, with regular mountain bike tyres, there’s a bit of a compromise.
If the air pressure is too high, the tyre doesn’t have as wide or compliant of a gripping footprint on the ground, plus it bounces wildly off of things like roots and rocks. If the pressure is too low, however, pinch flats can occur when riding over those same obstacles, and tubeless tyres can even get “burped” right off the rim. As a result, most cyclists keep their tyres at a somewhere-in-between pressure that isn’t ideal for either grip or protection.
Procore addresses this situation. Essentially, it allows cyclists to install a high-pressure inner tube (the blue thing in the photo), inside their existing tubeless tyre. That tube doesn’t take up all of the space inside, however – there’s still an air space between it and the inside wall of the tyre. For simplicity, Schwalbe refers to the tube as the inner chamber, and the space as the outer chamber.
The tube can be inflated up to 87 psi (6 bar), allowing it to serve as a firm pinch-flat-protection cushion, and to provide enough pressure to keep the tyre seated securely on the rim. This means that the outer chamber – which is inflated separately – can be run as low as 12 psi (0.8 bar). With conventional tyres, most riders don’t go much below 20 psi (1.4 bar).
As an added benefit, if the outer chamber is punctured and goes flat, the air in the tube will still allow the user to ride home. Flats in the outer chamber shouldn’t be too common, though, as the Procore kit includes sealant that will plug smaller punctures.