It is closed cell. It does not really soak it up like a sponge, but it is more surface area for the sealant to stick to. The side profile looks open cell because it has been cut to shape from a sheet, rather than molded, so the cells on the edge are exposed. The material is surprisingly rigid for the weight. I like it. Running it in my 26+ hardtail, and just like Andrew's experience, it has finally allowed me to be able to run more normalized pressures in those + tires (WTB rangers with tough casing) without constant fear of smashing the rim and pinch flatting or breaking something.
I think something else I have observed that is really important to point out, is that the weight of these inserts does not influence the feel of the bike the same way that a equivocally heavier casing would influence the feel of the bike. Keeping a supple casing that conforms to the trail irregularities really helps preserve the tires rolling speed. Stiff casings offer protection but roll lousy and can really feel a drag, supple casing with an insert still rolls fast and adds back a lot of that protection. It adds Some weight, so that's not exactly going to help your pace uphill, but its really not nearly as dramatic as you might fear. Carbon-lightness'itis has made everyone needlessly paranoid about adding a half a pound here or there. Especially when it comes to their wheels. It was the fatbikes and plus bikes that really finally made me realize this. The bike weights and tire/wheel weights defied commonly accepted logic for how fast they roll through a lot of terrain, especially in "pedaling your mountain bike" scenarios.
April 26, 2017, 11:45 a.m. - Metacomet
It is closed cell. It does not really soak it up like a sponge, but it is more surface area for the sealant to stick to. The side profile looks open cell because it has been cut to shape from a sheet, rather than molded, so the cells on the edge are exposed. The material is surprisingly rigid for the weight. I like it. Running it in my 26+ hardtail, and just like Andrew's experience, it has finally allowed me to be able to run more normalized pressures in those + tires (WTB rangers with tough casing) without constant fear of smashing the rim and pinch flatting or breaking something. I think something else I have observed that is really important to point out, is that the weight of these inserts does not influence the feel of the bike the same way that a equivocally heavier casing would influence the feel of the bike. Keeping a supple casing that conforms to the trail irregularities really helps preserve the tires rolling speed. Stiff casings offer protection but roll lousy and can really feel a drag, supple casing with an insert still rolls fast and adds back a lot of that protection. It adds Some weight, so that's not exactly going to help your pace uphill, but its really not nearly as dramatic as you might fear. Carbon-lightness'itis has made everyone needlessly paranoid about adding a half a pound here or there. Especially when it comes to their wheels. It was the fatbikes and plus bikes that really finally made me realize this. The bike weights and tire/wheel weights defied commonly accepted logic for how fast they roll through a lot of terrain, especially in "pedaling your mountain bike" scenarios.