I have been riding and fettling long enough to be able to sort this out but its got the better of me.
My Cranfield Yelly Screamy (hardtail) is prone to suffering from bad chain suck,I'm running two chain ring plus a bash guard up front where the third chain ring would normally be and a standard 9 ring cassette at the rear.Changing in middle rings of the cassette is fine, the problem is most noticeable when changing down to the granny ring with the chain in the lower geared area of the cassette and also in the granny ring with the last two of the higher gears on the cassette.
I think I have used one spacer washer on the BB bearing but can’t be sure without removing it. Can this problem be fixed be adding one or more spacer washers, thus altering the chain line or does the problem require a different fix ? Any advice, links, etc would be very welcome, thanks Paul