Towards the end of last season I moved over from a tried and tested combination of Schwalbe Rocket Ron 2.1 front and Kenda Small Block 8 2.0 rear to Continental X-King RS 2.1 front and back. These tyres are supposed to be a tubeless ready version of the Supersonic X-King, which its self is supposed to be a superlight XC race tyre for just about all conditions. At a glance, the tread pattern looks similar to the Schwalbe Rocket Ron with widely spaced aggressive knobs to clear mud quickly. They also live up to their billing as a superlight tyre, unfortunately I didn’t weigh them before I set them up but they felt at least as light as the tyres they replaced. Unfortunately, this is where the positives end.
Despite the RS version being designed to be run tubeless, it took about 6 months, and copious top-ups of sealant to get them sealed. Every time I went to ride them I had to top up the air pressure and there were always signs of sealant bubbling through the side wall. I have never had this with my previous set up (or my current set up) using standard, non-tubeless tyres. They must have swallowed so much sealant by now that the stated weights are half what they currently weigh. Admittedly, I should not have raced on leaky tyres but I don’t have the luxury of spare sets of wheels and this problem cost me positions in at least 2 races when I had to stop and pump them up.