Originally Posted by
Troul
PQD issue that slipped by the QA crew.
That chain is kinda sus. Did you buy it online?
No, Shimano CN-HG601 chain from the LBS. Stuff happens, I guess. Wasn't getting any skipping at all. Will measure for stretch later just to see but this is going in the bin regardless. Cassette teeth look great on all gears so hopefully I can just replace the chain and that'll be that. Definitely haven't seen a failure like this, I didn't even know this was possible. I was inspecting after lubing and I couldn't recall seeing that prior but given how clean the crack is I was almost wondering if it was by design for some reason and I had just never noticed it. Glad I noticed it at home and didn't break the chain miles and miles from home; I carry a quick link and tool but I'd still prefer to catch something like this at home than find out the hard way on the side of the road.
Thanks guys, now I know it's a failure.