Assembly of chopped mountain bike project started

January 22, 2010 · 4 comments

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preAssembly1The assembly is well underway and it’s exciting to see it all coming together. I still need to install the brakes, derailleurs, chain and wiring which will reveal some problems that need to be solved. I don’t anticipate anything major though. Once it’s together I get to go for a ride and see how it works. After that I’ll take it apart and paint the frame.

The motivation for doing this project in the first place can be read about in my post that highlighted the problems with the original design.

In summary, the main problems were stability and safety. I think I have solved these problems by
* Moving the batteries closer to the center of the bike
* Lowering the batteries
* Making the wheel base longer
* Replacing the aluminum bars with steel which doesn’t flex as much

As a side benefit the design also offers
* A secure storage for the batteries.
* Larger cargo area that can be used for other things and not the batteries

preAssembly2It might look fast but it’s not. This bike has to be pedaled. It’s not a moped; it’s a bicycle with power assist. This is fine for me. I’m not an athlete and I don’t want to go super fast. I like to ride bikes and pedal but not to the point where I feel like I’m going to cough up a lung and be drenched in sweat. I don’t own a car and I need transportation and a way to haul things. An electric bicycle is perfect for my needs.

Regarding the structural integrity of my modifications, I think it is somewhat over-designed to make sure the frame doesn’t collapse from the extra weight. I used large tubes for the extension and it seems very strong. I was thinking that it might need an added brace or gusset but it feels strong enough without it. In effect, the battery box acts as a brace by providing diagonal structural support from the lower back to the upper top so this will add some extra strength. The test will be to ride on a rough road with the bike fully loaded. Maybe I should wear full body armor. It will be done at a very slow speed for sure.

preAssembly3The battery box currently contains 48V 10ah SLA batteries. These weigh about 35lbs. When they wear out I’ll replace with LiFePO4 which should cut that weight in half and improve the handling even more.

Once the frame is painted and the bike reassembled, I want to replace the back rack with a deck that extends from the back of the seat post to the back of the rear tire. I’ll move the controller underneath the new deck. This will provide a really large cargo area. I like my electric cargo bike but this could be my goto bike for most trips to the store. I’ll reserve the cargo bike for when I need to carry over 100 pounds in one load.

For more finishing touches I’ll box in the battery box with aluminum sides and top. This will make for a clean look and provide a place to mount the key switch and charging connector. It will also provide some weather proofing.

What do you think? Click on comments below and let me know. Do you have any questions? I’ll be more than happy to answer.

{ 4 comments… read them below or add one }

1 pdxebiker January 22, 2010 at 1:57 pm

That’s a nice looking build! The Brooks saddle with the gripless crusier bars is a nice look. :) Having followed the build, I’m sure it will be strong; any estimate on final weight w/o electronics?

2 DanR January 22, 2010 at 2:06 pm

Woodard – Project is looking good . I’m also curious about structural integrity… stay safe!

3 Dan January 24, 2010 at 9:38 pm

@pdxebiker – This weekend the bars got some grips and levers. They did look nice bare though.
When I tear it down for paint I’ll weigh the frame and let you know. I’ll also weigh it with everything minus the electrics.

@DanR – I put on the brakes and hooked up the motor and took it for a spin around the block. It seemed really stiff and strong. The true test will be on rough roads with lots of cargo. So far so good.

4 WaterSkipper January 25, 2010 at 3:17 pm

I would love love love an electric bike. I just hope the damn police don’t decide to try and make us get a license and insurance to ride it. There is NO WAY I would give them money for the ‘privilege’ to traverse around on my bike. NO WAY.

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