What's a normal amount of flex under load?
I have a Sugino XD double crank and my big ring is a 50t.
When under load (pedaling from a stop, butt off the seat) I can see a good 1/4 inch of movement (side to side) of the chain in the derailler. It's enough that the chain scrapes the inside of the derailler. Is this normal? I didn't notice this before on my Sugino XD triple with a 48t big ring. Could be that I don't have my derailler set up correctly though since I did have to remove/replace it. But I still think I would have noticed that much chain sway.