Servo controlled rear gear derailleur shift

[steelmesh]

Of any configuration on a pedal bike, i'm talking paving the cow path moving/guiding the chain just like the derailleur automatically...Anyone remember seeing/hearing/reading about one of these?

I'm thinking scratch built and using MCU controlled big RC servo programmed to shift-points or pot to sense position. I have a unique application I am trying to solve using a mid-mount motor chain drive and regenerative braking; keeping variable drive ratios. I have some funky tensioning systems to handle the reversed power-transmission, so I can't just automatically drive a hand shifter using a standard derailleur.

 

[slofunk]

This may be of interest.
http://www.diyshift.com/technical.html

 

[steelmesh]

Thanks slofunk =)


Also: http://hackaday.com/2012/06/06/electronic-bike-derailleur/

 

[heathyoung]

Indestructables had one as well IIRC...

 

[steelmesh]

Trying to get something done for maker faire this weekend. Two spring loaded pivots...when you reverse the torque the lower dual pulley plate will rotate pulling the single upper pulley down, tensioning the top side by providing positive feedback to always keep the chain tight. I have to now design the shift portion, much like geometry of regular derailleur, but beefier.

This is a concept prototype.

 

[steelmesh]

In the mean time, here is a quick & dirty gadget I am playing with... servo shifter prototype: https://www.youtube.com/watch?v=WrD5DC9V1jk

 

[steelmesh]

Here is a prototype of a servo shifter mocked up and tested on the bike: http://www.youtube.com/watch?v=3pz1GatDktY