Originally Posted by
Andrew R Stewart
Generally when replacing the cog set (freewheel) one also replaces the chain, cut to size.
Some rear ders don't work with the larger in diameter cogs that a 34 is, compared to the 28T. Are you sure yours will? Andy
Ooops I can’t believe I didn’t think of that potential gotcha
Clegg2 - you shouldn’t need the lateral movement adjusting as the cogs are all the same width as the existing ones so same cable position and pull needed, but assuming your rear mech is ok with this 34 cog as per Andy’s warning, you could well need to adjust what’s called the B screw. It changes the distance between the pulley wheel cage and the cogs, might need to open that up a bit so the derraileur clears the bottom of that new bigger cog as it swings under it.