Thanks. I actually have one, but I rarely use it. Whenever I service and/or rebuild a bike I tend to replace the chain anyway, and given the number of bikes I have, I am never, ever going to wear out a chain myself.

In this particular case it happened with this bike I'd just bought. The seller had told me at least three times that it could not be ridden anymore, and that the bike was for display purposes only. Having seen the pics in the ad, I'd made a bet with myself that it wouldn't need much more than a bit of air in the tubes, a clean and and a lube:



So, right after picking up the bike and taking this picture, I put some air in the tires, adjusted the saddle, tightened the FD cable and went off for a ride. Almost at the end, a couple of hundred yards from my home, is a short incline, where I stood on the pedals, and that's where the chain snapped.