It could be the quality of the brakes (pads) since the total weight of the bike plus rider isn't that much greater than a similar bike 20 pounds lighter (200 pound rider + 70 pound bike = 270 pounds, while a 50 pound bike = 250). You might try Shimano 200 hydraulics which on my Giant MTB stop well, are durable and inexpensive. Hydraulics are installed on premium bikes for a reason - they perform better. I don't think regen is an option since all mids that I'm familiar with have geared motors.