Originally Posted by
non-fixie
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.
I could be wrong but the forks look a tiny bit bent. But like all metal fatigue it always finds the weakest
link (Ba dum tis) This article might shed some light on this
https://www.sheldonbrown.com/chain-wear.html But basically the link pins grind against the bushings, if the bushing somehow gets stuck the pins/blushings may start grinding against the side plates, and eventually something breaks. Chain stretch imho can be caused by other factors to like how strong a rider is and how much torque they are placing on a chain or if a chain is too tight etc.
This is speculation on my part but I think you don't see chains breaking as often these days because one of the signs of a worn chain can be trouble shifting. Where as old bikes like these you could still shift with the friction shifters so people got much more mileage out of them.