For those of you who missed the first installment of this post, see:
Project prototype 2.5

After completing the construction and testing of the “second prototype” (2.5), it was time to design, fabricate, and test the final prototype.

Here are a few pictures of the final design:

prot_3_comp_design

prot_3_installed

and a progression of the designs through the year:

design_progression

Further details of the project can be found at:
Bike Brake WordPress

For the Arduino code:
Regenerative bike brake code