Teeth do break. Case-hardened steel plates of 9-speed thickness are not very strong laterally. Had you had an XT cassette on when that happed, it would also have broken, the steel being exactly the same on both. I agree that fancier chains don't rust.....on their sideplates. These are chromed and resist rust more than naked steel chains. However, sideplate rust is cosmetic and doesn't affect the chain at all. Where it matters, in the swivelling interfaces, both will rust equally quickly. You'll find that light or heavy people who have developed a good shifting technique will seldom break a chain. I can however foresee that a strong, heavy rider will break a chain easier when doing a poor shift than a bantamweight. But JB the XTR Big Cogs down to 21 are made of titanium, not steel? your comment confuses me... The XTR chain is Zinc Alloy plated both inner and outer, the XT is plated only outer, they both weigh the same, but I stand by my comment lube after every ride, preferably with Squirt (i.e. do not clean with detergent, just wipe with a clean rag and Lube) I use a Rapid rise, I am not too sure wheter this puts less or more Shear Stress on the chain than a conventional Derailleur??
