For the 2012 North American Handmade Bicycle Show, Paul Brodie astounded us by recreating, piece by piece, an 1888 Whippet full-suspension bicycle. He took us through every stage of machining each linkage, crank arm and frame tube, resulting in a museum-worthy work of engineering art. Paul teaches Framebuilding 101 at Canada’s University of the Fraser Valley and he’s got the credentials to do so: he’s a godfather of modern mountain biking, starting Brodie Research and Technology in 1986 and eventually building some of the most highly sought after frames in western Canada and the US.
The 2013 NAHBS will see Paul return with another epic. If the Whippet was a blast from the past, get ready for a bicycle that embraces the future of urban transportation: the eBee. Join with us as Paul takes us through each step of creating one of the most significant and useful electronically-assisted bicycles ever created.
“It started last March as NAHBS 2012 was winding down. I wandered over to see Sam Whittingham in his Naked booth, and we chatted about the show. After a while we got onto the subject of what we might do for this year’s 2013 show, and I volunteered that I was considering an electric bicycle. Sam said, “You know what? If you do an electric bicycle, half the people here will love it, and half the people will hate it, so DO IT!” His comment really helped me commit to this project.
“My very next Framebuilding 101 course had 4 students, and 3 of them owned electric bicycles. Of those 3, one student, Justin Lemire-Elmore, owns Grin Technologies, a business that specializes in supplying motors and parts to convert standard bicycles into electric bicycles. I was very surprised to find out that he has eleven employees! I still had not ridden an electric bicycle, but that would change very soon. Another student, Mike Clegg, came to my shop with 2 electric bikes in the back of his SUV. They were cruisers, and had the BionX electric assist. This means that if you didn’t pedal, you didn’t go. I liked that. I pedaled down the street and it felt like a big helping hand was pushing me along. I came back with a big grin on my face. Another friend was over, so I told him to go up and down the street. He said no. I insisted, and he too came back with a big grin on his face.
“My time was all filled up for most of the year, but I could start working on the electric bike full time on November 15. In September I started sketching out a few ideas. I had no idea what this bike would finally look like. At first I wanted to hide everything electric away under a carbon fiber clam shell. That was my plan. I wanted to build it on a modular platform, to allow for future design changes, if necessary. There would be a tubular trellis frame and the motor, controller, batteries and swing arm would all bolt to this.
“I did another, more refined drawing, and now the electric components were all suspended below the frame. The idea was to get the motor down low between the crank set… to build the equivalent of a motorcycle road racer for the street. I was sold on ‘Mid-Drive’; where the motor is between the wheels. This way, the motor drives the BB and you can use the bicycle gears as a transmission to get more efficiency from the motor. Most e-bikes use a motor in the rear hub. It’s the cheapest way to build an electric bicycle. However, no matter how many gears the rider has, the motor is still only one speed. Your top speed is limited, and you can only climb a certain grade before the motor starts to overheat.
“I wanted to be able to do 30mph on the flats, and be able to climb any hill. I wanted suspension, big fat street tires, and good brakes. I knew it would have a motorcycle influence, and it might blur the lines between bicycle and motorcycle. I did some research on the net and found videos of some very fast electric bicycles. They’re running at 72 volts, a couple at 110 volts! Top speed is 60mph. More voltage means more power. A lot of the technology comes directly from the R/C world, which has made huge strides in the past decade. There is now a 5 HP motor that fits into the palm of your hand… Bikes like this can wheelie up and down the street, and the rider never needs to pedal. That was not what I wanted.
“I went to see Justin at Grin Technologies, and he set me up with one of their new red Stokemonkey motors, pictured below. These are known for their torque, making the power delivery very linear. The motor shaft is fixed, and the motor body turns at 350 rpm maximum. That would require a jackshaft with a 3.5:1 reduction ratio. Designing and building this bike was like assembling a giant puzzle; a lot like designing a very small motorcycle with 3 chain lines. Trying to get all the components to fit into a compact package that operates efficiently and looks good at the same time was a real brain teaser. This is my workbench as I am figuring out the side plates for the first time:
“eBee’s name came out of the blue. I wasn’t trying to find a name; eBee was just in my consciousness, suddenly, one afternoon, so I wrote it down. eBee is short for Electric Bicycle. Below is the frame jig used to build eBee’s frame. Pretty straight forward. Head angle is 69 degrees:
“I made a fixture that held both top tubes at once for the mitering process, shown here in the shop milling machine:
“Because the motor exerts a lot of torque, the shafts have to be held very firmly, and aluminum just isn’t strong enough. Here, I’ve milled out the aluminum mount to hold a 304 stainless steel insert, to be held in with a couple 5mm countersunk Allen screws. The slot is made using a boring head and moving the mill table sideways. Depth of each cut is .025″.
“The axle holder is flipped over in the mill vise and bored out to fit the BMX freewheel. Ultimately, it got redesigned and thrown in the scrap bin:
“I had planned to hide everything electric away under a large carbon fiber clam shell, but the motor shaft was wider than I expected, so the New Plan was to get the motor shaft outside of the crank arm circle. Which meant, upwards and forward. Instead of hiding everything electric, I’d now showcase the motor and everything else. I’ve always felt that each part should be able to stand on its own in terms of function and artistic design. I had an idea, but no actual drawing as I started making parts out of metal:
“I used a 44mm head tube from Paragon Machine and the tubing is 3/4″ 4130 with an .049″ wall thickness. The smaller cross braces are 5/8″ True Temper 4130 with an .035″ wall thickness. Tube bending from Andrew at Pacific Bending in Maple Ridge. Thank you. TIG welding was used to join all the tubes together:
“These are the rusty plates of steel I am using for the rear dropouts. I have made a sketch and have a few measurements, and that is good enough. I thought the plates were mild steel, but as I started machining, I realized I had picked up some tough steel that had a very good carbon content. These will help to hold the Rohloff rear hub securely, giving eBee a 14 speed transmission:
“There’s my cardboard template, and you can see the basic slot outline has been done in the milling machine, using a sharp end mill:
“I hadn’t been happy with the angular shapes of the 2 side plates and one afternoon I had the idea to really enlarge the radii around the bolt holes, and then scoop out the material between those arcs. That looked much better. Here, the left side plate is mounted on the rotary table and a cut made to give chain clearance. I do not have a CNC mill. Figuring out 3 chain lines made me scratch my head quite a bit:
“In total I made 5 sets of side plates before I ‘got it right’. Could I have figured this all out on a 3D drawing program like Solidworks? I don’t know. I think I need to have the metal in my hands, life size:
“I made a new rear dropout to replace the original Rohloff item. Because the rear frame is so low, the brake caliper mount can be canted forward much more. Material is 7075 aluminum:
“Setting up the chain stay jig to build the rear. The Hope brakes and front hub have arrived. Nice stuff!