you can buy longer b-screws on ebay or i have threaded mine backwards so the screw head meets the tab. running admittedly not very nice 9 spd lx mech on 40t largest sprocket perfectly
This set up (40t x 12-42t) works perfectly as the rear mech was meant to clear a 36 I believe when set up with a triple! So a 42 rear is no drama at all.
Very efficient way of getting a nice low range on a 10 speed set up for not much money!
you can buy longer b-screws on ebay or i have threaded mine backwards so the screw head meets the tab. running admittedly not very nice 9 spd lx mech on 40t largest sprocket perfectly