hi Geoff,
thank you for the table that really helped me understand how it works

well, i have decided to buy the 15t freewheel that miles found for me, thanks miles.
I'm amazed that i would need 72t at 90 cadence to achieve 35mph, that would make my chainring almost bigger than the crank arm!!
i think with 15/52 i will be ok, close enough to 30 is good enough.
the problem i have with having a cluster (giving me as low as 11t) is two fold - firstly i dont want a dished wheel, which with my puma means no cluster, secondly even if i had the cluster although it would give me a wider range of gearing i think that it would be wasted - lets say i had a 7 speed for example, how many of those gears would i actually be able to select in the short timeframe that it takes the puma to hit top speed? 1? 2 maybe?
i think 3 speed is the perfect answer for me - which can all be done at the front as luck would have it.
i'm hoping that 1st 2nd 3rd will be selectable whilst i wind the puma up to top speed enabling me to pedal right through the acceleration up to 30mph, after that i only have another 5mph which the motor should do by itself no prob as it will be up to speed?
As long as i have the pedal range 0-30 i'll be totally happy, it will be enable me to assist up any hill and at any speed which is what i'm after - oh that prompts another question, because my hub and drivetrain are completely seperate does that mean that i will be able to go up/down the gears regardless of motor speed also?
Does anyone want to have a stab at the question about the original front deraileur? i think it will work but we will see
thanks for the help guys,
D