Rear derailleur chain route.

Sharing what mechanics know but I did not.

There are two cage tabs on the rear derailleur, one for each pulley wheel. The chain should go between each RD pulley wheel and its cage tab. I missed both cage tabs and had to remove the chain twice to fix each error. It would have been faster to fix both errors at once, or better yet to have put the chain in correctly the first time.

I think I now have the chain routed correctly as shown in the photos.