Rear der. problem

The upper gear on the pulley is grinding slightly on the largest cog on the rear cassette. I’ve moved the B set screw as far as it will go, but it is still grinding. Any ideas on what I can do to fix it?

Shorten your chain a link or two
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As record man said or… Get a new frame that was built in compliance with Shimano standards. What kind of frame is this?

This is a Trek A1000. OK, hold down the snickering.
It has a Sora component group, OK, no open laughter.

It was/is my first ever bike, I got a cheap one ($525) to see if I even liked cycling and triathlon. It would be perfectly acceptable if I could just keep it working smoothly. The der. requires maintenance every week or two.

That’s a nice bike. You should be getting good rear shifting performance from it. I think recordti9’s comment about the chain is even more important now. Also, I wonder if the rear derailleaur hanger is bent upward a little bit…