Homemade e-bike

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Joined: 06/17/2007
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Points: 62

I live in China, the land of the cheap e-biked. I have been tempted to buy one here - can get them for as cheap as $US 120 but the quality and safety (or lack of) has stopped me. Speaking of stopping, the biggest issue is that the braking capabilities of these bikes is not any different from that of a pedal bike, yet the e-bikes are at least 50 pounds heavier and travel at 2.5 times the speed. Below is what I am planning/thinking of. I have not picked a donor bike yet. Please feel free to comment on any point.

1. I want the bike to still be easy to pedal and have gears. There are several internal hub gear boxes available here. I was going to put one on the rear wheel and put the motor on the front wheel.

2. I saw a motor once that was mounted on the front wheel. It was not a hub wheel but a typical looking motor mounted above the fender, with a chain drive to the front wheel. Is this a good idea? The reason why I want to stay away from hub motors is that they are much more expensive. The bike I saw had a 48 volt 6 or 700 watt motor that cost about $110.

3. If I had this kind of setup would I be able to put an internal hub gear box up front also, matched to the motor?

4. Would there be any benefit in using a motor with dual shafts, one at each end, and having a chain connecting each side of the motor to each side of the wheel? My initial thinking is that it might make less wear on the wheel because the pull is balanced from side to side.

5. Any suggestions on a donor bike? I am partial to the beach type bike because the pedaling position is more upright. I would prefer, however, a bike that had a longer wheelbase. Is it possible to safely modify a standard bike frame - cheap type, common steel, to extend the frame to make a place for batteries, i.e. behind the seat post and in front of the rear wheel? I would also like to be able to often carry another person behind me on the rack.

6. Has anyone installed a windshield on their e-bike? If so what was the result?

7. Has anyone ever converted a light - 100 or 150 cc motorcycle? I know the extra weight would eat some mileage and performance...but it would look really cool. Would probably not be able to pedal though..or not very comfortably.

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Gman's picture
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Joined: 11/21/2006
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Points: 1723
Re: Homemade e-bike

`pengyou
Welcome to the Vis for Voltage Community, your the second person from China to join our Community that I know of this week.
Nice to see we are growing globally.
Others will provide much better information than I can, I currently only have a Luyuan what we call a E Scooter. I'm planning on building a E Bike so I'm trying to learn like you.
I suggest a good start would be our Building E-Bikes Collaborative Hand Books.

Peace Out,
Gman

Now that we have clarified our beliefs, your invited to join us as we begin building on them to define our Community Mission Statement

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Peace Out,
Gman

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Joined: 11/19/2006
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Points: 144
Re: Homemade e-bike

Hi and welcome. I have been thinking of trying something like that myself. Adding the front gear box will complicate the project and add extra expense. If you are wanting to do this on a budget take a few ideas from this rig. http://www.austinev.org/evalbum/346

You will need to take care with internal shift hub/gear box selection. Many will not be up to the power of a 750w motor and could fail during shifts under power, usually the pawls on the freewheel let go. Also take a look at the size of sprocket required if there is no prior gear reduction. MB-1-E here has posted a blog that includes gear reduction for this type of application, he however is using a rear mount motor.

As for bicycle selection a steel frame is a good way to go but the cruiser bikes often are quite short in the braking department. So be sure to select one that has at least provisions for front brakes. If you like a more upright riding position just about any cycle can be fitted with a riser and cruiser type bars, so don't rule out the mountain bike as they often have more braking power and options.kona_done1.jpg

You can see here how I set mine up for upright riding position.

When it comes to what will fit it is my understanding that Chinese bikes have far different standard sizes of rear hub spacing, etc. so measure it all three times before deciding what you want to add from outside China source parts.

Best of luck and keep us informed of what is happening with your project and of any unique parts we may not know about available in your country. I think we have no idea what can be had there for bikes. Your people have been using them as a main form of transportation so long.

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Joined: 04/06/2011
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Points: 34
Re: Homemade e-bike

This is really on old post and not updation. I think current e bike conversion is very easy.

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