Pchen92, it think the answer to your post was in the following one from Kepler,
Kepler, yes i made a new shaft, (the original is now residing in Aus) the bearings in the motor where changed to 3/4" bore ones allowing me to use thicker journals, i also increased the size of the oil seal to 24mm i/d to run on a spacer which protects the wires. The spindle is in fact made of 2011t3 alluminium
with having large square ends and not having a thread with a small core dia and 2 flats i could do this. This alloy machines very nicely which allows the accurate dimensions needed for good bearing fits and has good mechanical strength.
Data sheet;http://www.aalco.co.uk/datasheets/Alumi ... -T3_3.ashx
The machining of the lefthand 30x1mm thread is really easy as you work left to right with the tool running away from the work piece, far easier than doing a right hand thread where you have to work towards the work piece with stopping in time being critical! place the tool in an undercut then engage the feed, the tool travels off the end of the thread, easy! well it would have been, my small metric lathe didnt have enough swing, i made the brass adaptor on it but had to go and do the side cover on a bigger DSG 13x42, a much bigger machine, this had the complication of an imperial lead screw which makes you scratch your head a little!!
I also changed the woodruf key to full length (and made it fit properly) (the only job on the whole bike that a cnc was used for)There is also another bearing inside the brass sprocket mounting directly in line with the chain to support the sprocket carrier and take the load off the threads. It seems to be a solid design.
The pedal cadence i learnt from having built the previous bike, we learnt that having the driven sprocket slightly larger than the driving one makes for a much more suited pedal speed. i could have used 2 48t rings but i would sooner have better ratios at lower speeds, flat out i am just hanging on not pedaling!!