I've had this chain, a cheap KMC Z410 since I put the bike together for some time, perhaps . I used to have an All-City crankset, which I've since replaced with a SRAM Omnium. Given the Omnium's 'unique' qualities, I figured that this may have been caused by an off-center spider. When I spun the crank with no chainring, the spider arms weren't noticeably off-center. My FSA rings are very round, with not enough deviation to make the chain flex like this. I have an All-City ring that isn't as round as the FSA ring, but even that is only a millimeter out of round at most. The rear hub in the videos is an older Surly track hub, with loose ball bearings. The cones are a little loose right now, and they aren't centered perfectly on the hub meaning that the chainline is probably a little off. However, I have a set of wheels with sealed bearings, with no such cones to adjust and I still have similar issues. I'm wondering if it could be the fact that my All-City cogs aren't as wide as say, Dura-Ace cogs, again throwing off the chainline:
(All-City on the left, Dura-Ace on the right)
Finally, I'm wondering if the chain itself could be the culprit. Though there are no stiff links, I didn't use the master link, and thus reinserted pins once or twice (I may have trimmed the chain down a couple of times).
NB: I'll feel very silly indeed if this is just a typical symptom of a chain that's too tight.
Interesting. I'd had no idea that the pattern I tightened the bolts could have any effect. I usually do it in a star pattern because I'd heard that I should, but never knew why. Lately I've been more complacent about it and have been doing it in order. I'll have to do it in a star pattern from now on.