Shifting is crunchy in Shimano CB-E110 Looking for advice for my GFs Pelago Brooklyn, which has a coaster brake Shimano CB-E110 hub. When shifting gears, the chain hops and crunches. The chain also looks a bit saggy. I only have experience with maintaining single speed and fixed bikes, so I was wondering what can I do for it?
Pelago web site says this bike comes singe speed or with a 3 or 9 internally geared hub, CB-E110 is a single speed coaster brake hub, so perhaps you actually have one of the IGH options.

If the chain is skipping over the rear sprocket the the chain tension needs adjusting, just as on a single speed.