One problem i see is that if you don't brake often you have 8 more pounds to carry for free.
Could be interesting to combine this system with other energy sources mechanical (piezoelectric), thermal, wind, solar, chemical or have your regenerative braking system work at different stages of the ride (going downhill, reaching a complete stop and whatever other stages you can find)
Last edited by erig007; 09-23-13 at 11:00 PM.