Imagine the Left crank is removed and replaced with a "NEW" crank that allows the rider to pedal normally by maintaing the mechanical connection to the spindle. But the crank provides a slip ring for a brusless motor to rotate on with a stator structure that can clasp the bike frame (ie near the drink bottle holder).
I have considered the available space around the left crank as it rotated, and can invisage enought volume to fit a 250W- 500W brushless motor (Custom designed of course).
I have been wanting to power my giant NRS full suspension MTB with a Mid Drive system.
As the rear hubs often have mounting for brake disks this could be used for chain sprocket. The chain linking the motor would need a tesnioner. But the beauty of the left drive approach allows regenertive braking to be applied.
The intergrated motor/crank is quite complex due to slip rings and bearings.
So if the design worked effectively sales would have to quite high to make it cost effective.
I have thought of ways to include crank torque sensing so a throttle doesn't have to be used and just apply a tourque multiplier like some other ebike use.
The concept never left my mind for the last few years as I see people investing up to AUD$4000 on moutain bikes. And I know I would rather retro fit a motor to my bike than buy a new one.
The other point is I just can't accept that a hub motor of 500W on a suspension arm front or rear would allow the suspension to operate effectively.
I love the optibike concept (http://www.optibike.com/Frontpage)
But would like to have some thing similiar that can easily be fitted to most bikes.
I probably will try a motor mounted under the bottle bracket first and run a chain to the slip ring on the left crank then another chain to the rear wheel. I'm sure someone has already done this. And it it would allow regen to.
I'm interested on comments on bikes that have really good regen braking.
And regen effectiveness with different battery chemistries.
Better stop here, it's my first post.
I have found this site great reading.
P.S. I hope this post doesn't end in war of words. Peace :P