Everyone knows an O or RX ring chain gives more drag, right? I called FTM to order two new RX 520XSO chains for this year. When I called in, and told them I want 2 520XSO RX Ring chains, the lady asked me - Is this for competition? (Since I am under the racer discount). I said yes . She said "Well, you know that's a real disadvantage to run that chain." I paused for a second in disbelief. My next comment "It's for a KTM 520, I need something that won't shred itself in 2 rides, and that bike doesn't even FEEL the extra drag" She said OK and placed the order. LOL. Extra drag. For a smaller bike, yeah, but not for a 520.