Here’s the second installment in Paul Brodie’s process diary of building the eBee, what could very well be the best designed electric bicycle ever assembled. This walk-through will be of great interest to anyone who’s ever thought about picking up a torch and building their own frame, as Paul teaches Framebuilding 101 at Canada’s University of the Fraser Valley and knows a bit about it:
“The chain stays have been Tig-tacked, and now the seat stay jig and a big C-clamp hold it all in place. The seat stays are now on, and it’s time to see eBee’s shape evolving and coming together. Yes, that is Bill and Hilary on my wall, in happier times:
“Detail of the fillet brazed dropout holders, Hope rear brake, and Rohloff hub. According to Justin, the only 2 hubs that will stand up to continuous electric motor power are the Rohloff and Nuvinci hubs:
“On the spot wiring diagram, courtesy of Justin:
“This is the complete package for eBee, minus the motor: (left to right) the 25 amp controller, Cycle Analyst computer, Thun BB, and the lithium polymer batteries. The small, but powerful, batteries are normally for R/C hobby airplanes. They are connected in series to produce 52 volts, giving the Stokemonkey motor an output of just over 700 watts, which translates to about one HP. The Cycle Analyst display is from Grin Technologies, and is the latest 3rd generation model. You can program when the motor starts to assist the rider, and by how much. It tracks battery life, and will automatically partially shut down when the batteries get too low. It can tell you how much energy you put into the ride, and how much the motor puts in… The Thun BB has integrated magnetic sensors that detect the mechanical strain on the BB spindle, and sends that signal, plus the cadence signal, to the Cycle Analyst, which tells the controller how much juice to send to the motor. A very slick system!
“Other parts. This is a mount for hanging the batteries and controller from the two side plates:
“Now in the mill vise, having the center section lightened with a 1/4” end mill:
“Finished, except for anodizing:
“I needed sprockets for the jackshaft, so I went to my local bearing supply house and purchased these two beauties, plus two bearings:
“Later, they were thinned, lightened, drilled, bead blasted and nickel plated. Ready for assembly:
“I needed to make sprockets for the $35 crankset I got off eBay, so I found an 1/8″plate of 7075 aluminum. Here it is setup on the rotary table, and 52 teeth means one cut with a 5/16” end mill every 6.923 degrees. A little bit of concentration was required:
“The boring head spins with a carbide insert tool and makes very smooth holes. The sprocket fits an 1/8″ X 1/2” pitch chain:
“eBee is starting to come alive! There is still LOTS to do:
Previously:
Paul Brodie eBee Part 1
