Electronic shifting servo mount (cable-actuated)

This was a failed design for an electronic shifting project I was working on. It's a mount plus other stuff for a standard servo to mount to the driveside chainstay of a bike & use it to actuate the rear derailleur using a standard shift cable.

It is used in addition to the user's current RD.

We tried this with the highest torque servo we had (about 20 kgf cm, I think), & it was far too weak for a double spring old Shimano 105 rear derailleur. I think we tried with more modern long cage Shimano Claris RD (single spring) & it still was too weak.

Incidentally, many months after I designed this, this appeared:
- https://www.kickstarter.com/projects/1598276649/xshifter-worlds-first-universal-wireless-smart-shi
- http://www.xshifter.com/

Which mounts similarly, & actuates similarly. I haven't played with them & I'm not sure how they got a strong enough servo/linear actuator, but they cost too much for me to find out.

Since it actuates over a very short cable length with no