I have been running a new Sram rival rear mech for a month or so & the chain has just started to hop on the smaller cassette gears. Could anybody tell me what the gap between the cassette & the jockey wheel adjusted via B-Screw should be ? I know it's around 6mm on MTB Sram XO or is the adjustment set - up different on a Sram road mech ? Thanks in advance for any help offered.
As far as I know, chain jump on small cassette cogs is generally only caused by two things - chain stretch or cassette wear. The amount of "wrap" you achieve by adjusting that screw can seem to make a difference on the stand but under load its a different story.
In my experience the chain line has more to do with this - check the alignment of the smallest rear cog and the largest chain ring. It could be the spacing on your BB or cassette. If its out of line you will get jumping no matter how much wrap you have.
Different cassettes can give different results as well. In my experience the dream combo is SRAM cassette and chain, Shimano mechs and shifters.
Thank you for the reply. I should have said that it is a brand new bike (2 months old) & has just settled in. All parts in perfect alignment & still jumping gears. I think it is just a slight re-alighment of rear mech & b-screw.