Instructables
Picture of 48V Electric Flat Tracker
About a year ago, my dad and I had the idea to convert a beach cruiser bike into an electric motorcycle. We purchased the bike and all the parts necessary and got to work. We modified the frame and rebuilt the bike from the ground up. When we finished, we were extremely satisfied with the results - a 48 volt, 15 horsepower board track racer.

 
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Step 1: The Components

Picture of The Components
We started with a Felt beach cruiser because it had the right look. We wanted a beefy bike that could fit all the components. The goal was to keep the center of gravity as low as possible. Here are the rest of the main components we purchased:
- Briggs and Stratton Etek motor (now discontinued)
- Alltrax AXE 300-amp programmable controller
- Magura 0-5K ohm twist-grip throttle
- 4 x 12V, 21Ah sealed lead acid batteries
- Avid BB7 mechanical disc brakes (160mm rotors)
- #35 moped chain
- 13-tooth drive sprocket
- 66-tooth rear sprocket
- big power switch
- 300-amp fuse
- 8 1/4 in. stainless steel motor mount (this replaces the original bottom bracket)

Step 2: Front Fork

Picture of Front Fork
We removed the original rigid front fork and replaced it with a Manitou suspension fork. We also bolted on an Avid disc brake set to the front end. We chose to go with mechanical discs instead of hydraulics simply because they are less expensive and less complicated. The Avid BB7's are fully adjustable. You can dial in each pad separately.

Step 3: Rear Brake Mount

Picture of Rear Brake Mount
Because the bike we purchased used coaster brakes (pedal backwards to stop), we had to fabricate a mount in the rear to accept our other disc brake. We used a jigsaw to cut out a piece of steel for the main shape. Next, we used a drill press to tap holes for the brake.

Step 4: Rear Hub/Sprocket

Picture of Rear Hub/Sprocket
The rear hub we used is designed as a "dual disc" front hub. It has a standard mountain bike 6 bolt disc pattern on both sides. We took a blank 66 tooth rear sprocket and drilled it to accept the 6 bolt pattern. The alignment of the hub, sprocket, and disc rotor are critical.
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When I talk about instructables to people, I use examples of exceptional work to illustrate it orally to them, yours is one of the ones that tops the list!
1up4 years ago
Without a doubt, the nicest electric bike I have ever seen. Amazing work.
KrisB14 months ago

Where did you get the dual disc hub?

WX4ME5 months ago

Great Work !!

please tell me how many watts rating of the DC motor are you using besides

the data sheet of the batteries.

Thanks

mmaciver5 months ago

It's been a few years since you've built this, and had all that time to ride, and test out your design. What can you say, about your choice of components? Have they withstood the test of time? I'm considering a similar build, on a different platform. I'd appreciate any advice you can give.

pdub775 months ago

This is fantastic. You have done well, sir.

samuraijack6 months ago

i like the look of the bike and i love the way you have chosen to put the engine and the batteries on the frame.

Reminds me of old retro racing bikes.

this project is 5 stars on the pretty f***n awesome scale .

nicely done.

i am jealous now.

peets7 months ago

i bet i weill go fast on tihs 1 lol

Squidyman7 months ago

I love the creativity!

I would doubt the 15 rated HP of that motor. 8 HP to 10 HP looks more like it. With 15 HP top speed should be around 75 mph!

Awesome project!

and I love the use of the light post. One of the most creative use of parts I have seen :D

aetourneau2 years ago
It is a amazing work!
I would also like to make one but where is that I could get back a motor ?
Sorry if y have made some mistakes, I'm French.

Check out robotmarketplace.com

They have this motor there

rjcullis1 year ago
I have modified bikes before. This really excites me. I have a trike that I look forward to adapting your concepts on. Thank you for your clear explanations. Any ideas where someone could pick up a similar motor (since yours is discontinued)?

Thanks,
Richard

Check out robotmarketplace.com

They have Eteks there

What kind of power switch did you use? Also, are the sprockets really necessary? Can't I just use the sprockets which are already on my bike?

Eleyan10 months ago

How much "hill time" do you think your design can muster for say, 95kg person, on one full charge?

rasik411 months ago
how about using bus or truck wiper motor(24v) for electric bicycle? what is maximum speed?
With the amount of speed that you claim for the EV-12 to reach you would have to get it registered as a motorcycle or risk the possibility of large fines and possible jail time.
It depends on the laws of your state. I know in North Carolina you don't have to register a bike that's under 50cc. However I don't know how electric bikes are covered there. You do raise a good point though. You want to make sure you know the laws where you live so you don't get yourself in trouble.
In B.C. Canada they have changed the law such that ANY gasoline powered vehicle must be inspected and licensed.
For most US states the limit is 50cc and/or 2 bhp. So electrics would be limited to that 2 horse power range.
Many of those states also require that the top speed be either 30 or 40 mph but it looks like this thing may be doing better than that.
God you are stupid. It's a bike, thats electric. No where does anyone say you have to get it registered as a motor bike. They sell commercial ones all over the world, and the don't have to get theirs registered and they go way faster.
No that would be you.
Once you hit 60cc's then its considered a moped.
Well, I guess I'm in Canada and they don't have to be registered, but I don't know in the US.
In B.C. they do! You are only allowed <500W anything bigger must be registered and licensed as a motor bike.
they don't go by "CC's" when talking about an electric propelled vehicle; CA law allows for no more than 1000 Watts power output, so he's WAY over!, and 30mph max speed, on flat, even terrain. He'd get a ticket for sure! In CA they may take his ride, and that would just suck! Most states have a limit of 25 to 30 mph, as a general rule. as far as engine size goes, for a motorized bike, some states accept up to 125cc (to allow for the Whizzer Motorbikes), while other's don't have a law for them, or electrics... check out www.moped2.org If you suffer from pain, like me, and have many hours awake in bed, you might be interested in reading about your state, or all of them!
In my state it's 50cc and 30mph, if I recall correctly. I don't recall the regs on electrics. I have read that they go by speed, (either what it will do by itself, or the speed it assists you reaching if you are pedaling), and they are very strict.
i live in dunkirk ny where i have a friend that has recieved 7+ tickets for a store bought toy electric scooter. unreg vehical no plates no signal no insurance lots and it is messed up kids cant ride them even if their parents got it from the store
Yeah, I was bored the other night, and went though all 50 states (and Puerto Rico) looking at the motorized bicycle/moped/scooter laws... NY state sucks in this regard; they will not even allow it in a parking lot! I'm sure there are places upstate that may be cool, but if they go by their laws... they really SUCK! I am so glad I don't live in that fu*^#%@ state!
If you ride it on private property with permission, you don't need to get it registered. I don't think the cops will mind too much as long as you only ride it around the neighbourhood responsibly, and don't annoy any neighbours or cause problems with traffic.
If you're not driving on roads you don't have to register anything.
Even if you were on roads you would not have to register it.
There's a specialized registration in my state for motorized bicycles.
Oh, please - "jail time"?
I agree.
Well actually in my State at least. If you leave the peddles and crank on it, they consider it still a bicycle and would be legal. Bicycles already have to obey the rules of the road just like cars. That means remaining under the speed limits and obeying all other traffic laws for the state. The only thing you wouldn't have to do is register it as a motor vehicle. If you look at most of the videos on youtube and such the bikes have digital speedometers on them.
Nice looking bike! which is often the problem with electric bikes, the batteries are plug ugly making them hard to design - unless you can hide them under a fairing, your design is very clever.. though its not like looking at a Guzzi etc.. Problem with your Ebike is it would be impounded in 5 minutes in Australia. No more than 250 watts is permissible on a bicycle - and then you also need to have pedal assist, otherwise its classified as a motorbike. Over 250 is private property only, there is a switchable 250/1000 watt conversion available, which is (sort of...) legal. BTW - those brakes may be ok for pulling up around 100kgs at low speeds, they are not designed for that amount of power and added weight though, i would upgrade them.
amaineman574 years ago
Hopefully you will carefully take note of your bearings and ability to stop at those speeds. A cruiser bicycle is not usually taken up to such speed. Tires too can fail catastrophically when over sped past their designed limits.
He does seem to have "beefy" tires, i'm not sure what the exact limits are for those tires so it may be possible. However the disc brakes are a real help. Of course your post is not without merit 50mph is FAST.
My younger brothers had a busted up pedal type moped that may be a good source if I get the chance to try something like this. I'd have never thought of that till the landing LOL thanks!
is this considered a motorcycle or a moped? What would the equivalent cc's be based on output?
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