The B4 manual says with the
kit standard 81t/48dp spur a Final Drive Ratio of around 9.5 is recommended... I use 23t pinion with 81t spur(both 48dp)which gives FDR of @9.1... I'm running a Novak 10.5 EX...
So I guess the answer to the Q is:- a FDR of around 9 -10 will be fine...
Is the spur 48dp or 64dp 'cos 100t/48dp seems a bit undergeared..i.e. faster acceleration but low top speed..(for a given pinion)
Drop onto the associated website and download the build manual... the info is in there...
I hope this helps, but if not ping me back...
