New Bike from Rose Bikes (Germany): https://www.rosebikes.com/p/rose-backroad-al-grx-rx610-1×12-ts-2728334
It has this rear derailleur: Shimano GRX RD-RX822, 12-speed
And only one front sprocket, so its a 1-12 speed.
It came with a not that well adjusted shifting so I adjusted it myself like in the proven parktool rear derailleur youtube video as I already did 100 times with other bikes.
After that the H and L limit screws are correct. The B-Screw is correct according to the manufacurer marking. The adjustment of the shifting seems perfect as every gear shifts perfectly fast without rubbing on the higher cog. The cassette seems to be mounted correctly as the distance between the cogs looks even.
Buuut I could not get rid of some problems:
On the largest cog the chain rubs against the lower cage end making noise (as the distance between it and the front sprocket is short in this gear and the lateral difference ist pretty high.)
On the largest cog, when backpedaling the chain sometimes jumps down 1 or two cogs.
On the smaller cogs there is a lower rubbing noise that I can not locate.
Is this common with a 1-12 shifting? Do I just have to live with the noise? Or is there some trick that I am missing?
by GustavGans