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.
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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.