Running a full xt drivetrain on my orange five. When in the highest ring at the back and the small/middle ring at the front i get a horrible noise when putting power through the pedals, almost like a grinding/crunching noise.
All my end points are spot on, my gears change smoothly and i've fiddled with the height adjuster on the rear mech. The only thing i can think now is that th chainline is poor in the easier gears or something isn't quite right with the xt mech as a friends does exactly the same.
Anyone experienced the same?

Hugh

It's probably the B screw (height adjuster), it happened on my 5 with an X9 mech, I found that adjusting the mech so it was further away from the cassette helped stop the noise.