I have set up a number of bikes with 10-tooth front
chainring gaps, Nuovo Record rear derailleurs, and 28
tooth low gear cogs. Two things are necessary--the
shortest possible chain, and reassembling the dropout
adjusters so that the axle can be placed as far back
as possible in the dropout slot--remove the spring
from between the head of the adjuster screw and the
inside surface of the dropout and replace it between
the outside (rearmost) surface of the dropout and the
little adjuster knob. Set the rear wheel back
absolutely as far as possible in the dropouts. Cut
the chain to the length that just barely will let it
be shifted to the large chainring/28tooth combination.
It may grind a little going onto and off of the
28/small ring combination but it will make that shift
reliably and consistently.
David Feldman
Vancouver, WA