jdcburg
100 W
Here are some pix of my new ebike. I acquired a matched pair of old Huffy 3-speed bikes - the kind with the internal gears in the rear axle - what we called an English bike when I was growing up. I put the rear wheel from one on the front of the other with the sprocket on the right so it will engage to drive forward and freewheel when the motor is shut off. I wanted a bike that I could pedal but with an assist for the hills around here (New England). I used a 350W geared down motor from a Razor Dirt Quad over that wheel. Because I decided I would be using the motor at full power and pedaling to start, I ended up using a 40 amp Bosch type relay and a momentary toggle switch.
I mounted the batteries (2-12v 12ah sla's) between my legs above the crank.
The Razor motor had a #25 sprocket on it. The shaft is 11mm (7/16") with a 2x4mm key so I bought a 9 tooth bike sprocket that fits the shaft. It was a little narrower so I had to file notches in a couple of 7/16 washers to shim it out. I built a rack out over the front wheel out of a 2x4, 2 pieces of 1x1 angle aluminum and some shelf brackets. The front rack is pretty solid, with the 2 1x1 angle aluminum pieces bolted to the front fork carrier as well as u-bolted to the handlebars.
I’ve taken it out for a couple of test runs and I'm happy with the way it performs. I had the 3-speed front axle set to low gear and it climbed "heart attack hill" near my house pretty well with me pedaling like I was on level ground. When I stopped pedaling, it slowed down to where I thought it might cause problems, but picked up nicely when I started pedaling again. Later I set the front axle to high gear and it went along on level ground about as fast as I could pedal comfortably in high gear - I'm guessing about 18-20 mph. I doubt if it will have enough "hill power" in high gear but I may get a shifter for the front axle sometime. For now I just tie it tight for low gear and let it loose for high gear.
Next, I went down into town - about 1 1/2 miles but also about 400 vertical feet. I think it was about 7 minutes down and 12-13 back up. I pedaled the whole way back and engaged the motor as a power assist on all but the most gradual inclines. I was able to maintain a speed that was about a fast jog with the effort it would take to pedal on level ground. That's faster than most bicyclists can pedal up that hill. I'm guessing the gearing on the motor is about 1:7. The motor sprocket is 9 teeth and the wheel sprocket is 19 teeth. The low gear in the hub has the wheel turn 3 times for every 4 sprocket revs. 2nd gear is 1:1 and 3rd is 5:4. I will continue testing and tweeking and will keep you posted.
The steering is a little different, especially under power, but it doesn't seem dangerous. (famous last words?) The brakes, however, are not great. They are the old style side pull calipers and the wheels are obviously not the highest quality - they each have a slight irregularity where the seam is welded, so they chatter and grab a bit. Also, I think I'll lose a lot of stop when they're wet. But the main thing is, the concept works. The bikes were free and have interchangeable parts, so that was convenient. I will probably redo it on a mountain bike or cruiser with either disc or center-pull calipers.
- jd
I mounted the batteries (2-12v 12ah sla's) between my legs above the crank.
The Razor motor had a #25 sprocket on it. The shaft is 11mm (7/16") with a 2x4mm key so I bought a 9 tooth bike sprocket that fits the shaft. It was a little narrower so I had to file notches in a couple of 7/16 washers to shim it out. I built a rack out over the front wheel out of a 2x4, 2 pieces of 1x1 angle aluminum and some shelf brackets. The front rack is pretty solid, with the 2 1x1 angle aluminum pieces bolted to the front fork carrier as well as u-bolted to the handlebars.
I’ve taken it out for a couple of test runs and I'm happy with the way it performs. I had the 3-speed front axle set to low gear and it climbed "heart attack hill" near my house pretty well with me pedaling like I was on level ground. When I stopped pedaling, it slowed down to where I thought it might cause problems, but picked up nicely when I started pedaling again. Later I set the front axle to high gear and it went along on level ground about as fast as I could pedal comfortably in high gear - I'm guessing about 18-20 mph. I doubt if it will have enough "hill power" in high gear but I may get a shifter for the front axle sometime. For now I just tie it tight for low gear and let it loose for high gear.
Next, I went down into town - about 1 1/2 miles but also about 400 vertical feet. I think it was about 7 minutes down and 12-13 back up. I pedaled the whole way back and engaged the motor as a power assist on all but the most gradual inclines. I was able to maintain a speed that was about a fast jog with the effort it would take to pedal on level ground. That's faster than most bicyclists can pedal up that hill. I'm guessing the gearing on the motor is about 1:7. The motor sprocket is 9 teeth and the wheel sprocket is 19 teeth. The low gear in the hub has the wheel turn 3 times for every 4 sprocket revs. 2nd gear is 1:1 and 3rd is 5:4. I will continue testing and tweeking and will keep you posted.
The steering is a little different, especially under power, but it doesn't seem dangerous. (famous last words?) The brakes, however, are not great. They are the old style side pull calipers and the wheels are obviously not the highest quality - they each have a slight irregularity where the seam is welded, so they chatter and grab a bit. Also, I think I'll lose a lot of stop when they're wet. But the main thing is, the concept works. The bikes were free and have interchangeable parts, so that was convenient. I will probably redo it on a mountain bike or cruiser with either disc or center-pull calipers.
- jd
if you had all whood parts made of metal instead it would be enven better!
