Originally Posted by
DArthurBrown
1. The chain shows little if any wear that I can measure.
2. No visible wear on that particular cog.
3. If the problem were in the big chainring, it seems like it would affect other combinations with the big chainring. In fact, the next smaller cog is silky smooth in combination with the big ring.
1. See my post above - can't be the chain, as worse chain angles and higher gears show no problems.
2. You cannot generally SEE the wear on a cog until it is extreme
3. Exactly the point I made above. The evidence points to the cog and nothing else.
Instead of focusing on what you think it isn't you need to focus on the only thing it can be. Replace the cog if you can, or the cassette, and the chain if things aren't smooth with a new cassette.