I have tektro cable pull brakes with 140 mm rotors on a cargo bike that I load up to 330 lb gross. (94 bike + tools, 160 lb me, 80lb supplies). It will stop quite competently on up to 15% grades. I can throw myself off the seat if I want to stop that fast. Stopping power does not deteriorate nearly as much in the rain as rim brakes do. I estimate rim brakes lose 75% of their stopping decceleration in the rain.
180 mm or 220 mm rotors may be just the thing for 250 lb riders that decend 2000 ' in an hour in a race. Not required for 160 lb me that decends 80 hills of 20' to 100 ' in 3 1/2 hours.
I have 5" long brake handles that came with the hub motor kit, which require less force than the 3.5" handles tektro equipped the bike with. I think the 3.5" handles are a sales promotion for hydraulic brakes, as tektro also sells those. The same way the big 3 changed drum brakes from 11" to 10" in 1960 to force buyers to pay for power brakes. Same way the big 3 cheapened the streering boxes from 1959 to 1962 to cause much more force to be required for manual steering, to force buyers to buy power steering. BTW I adjust my front brake every 1000 miles, or twice a year. It takes 2 minutes, most of that digging out the wrench and putting it away.
I find the passion for hydraulic brakes to be the same sort of mania as the passion for the number of engine valves or the word turbo, of the late eighties.
