Introduction: 48V Electric Flat Tracker

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.

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.

Step 5: Rear Drive Complete

Picture of Rear Drive Complete

Here the brake mount is welded on, the wheels have been laced to the hubs, and on the right side, the seat stay has been crimped to get clearance from the chain and sprocket. The axle tension adjusters we used were from Answer Products.

Step 6: Motor Mount and Foot Pegs

Picture of Motor Mount and Foot Pegs

The motor mount (cut from the same piece of steel as the brake mount) is welded into the stainless steel ring and the ring is welded into place, exactly center, replacing the original bottom bracket. The foot peg mounts are made from a couple of old work light stands welded together.

Step 7: Mount: Drilled and Welded

Picture of Mount: Drilled and Welded

Centering the motor ring is very important. The ring is a section of a stainless steel light post salvaged from a scrap yard cut to 4 1/4 inches wide. It is 8 1/4 inches in diameter which leaves about a 1/8 inch gap around the motor. It is perforated on the drill press to allow air flow to the motor and notched on the right side for chain clearance. The motor mount is welded offset inside the ring for optimal motor shaft and chain placement. Mounts are welded to the underside of the motor ring to accept the removable foot peg assembly. The foot pegs themselves are aluminum BMX "grinder" pegs.

Step 8: Seat Mount

Picture of Seat Mount

The original seat post was removed, cut short, and welded on the seat stay bridge over the rear tire and a gusset was added for strength. A rubber cap was put over the existing seat tube, and the seat clamp was flipped and reversed.

Step 9: Welding Complete

Picture of Welding Complete

Here you can see the bike coming together. The beefy wheels and lower saddle position give it a retro look. Notice the brazed on eyelets for the rear brake cable routing.

Step 10: First Assembly

Picture of First Assembly

The battery trays were fabricated from aluminum stock. Each tray was then riveted together and bolted to a right and left panel. The panels are then bolted to each side of the frame. Note the power switch in the center. The right and left panels are asymmetrical to accept the terminals on the back side of the power switch. The controller is mounted upside down under the top tube with the terminals pointing backwards.

Step 11: Final Assembly

Picture of Final Assembly

After we had finished the assembly, we had to wire it up. Within a few hours, we were testing it up and down the parking lot. It really accelerates quickly and we have not tested it for top speed. It is estimated to do better than 50 mph.
The controller we used can connect to a PC via a serial (RS-232) cable. With the freeware on their site,, you can view statistics in real time, change settings, and adjust the power curve for the throttle.

Step 12: The Maiden Voyage

Picture of The Maiden Voyage
This was the first chance we really got to ride the bike to its (almost) full potential. The bike is smooth, quiet, well-balanced, all torque and pretty fast. It's a blast to ride! After finishing it, we decided to call it the EV-12 for various reasons.


iminthebathroom (author)2011-05-25

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!

1up (author)2010-08-10

Without a doubt, the nicest electric bike I have ever seen. Amazing work.

Ehpac (author)2016-10-19

What is the average cost to make this bike??

Tenire (author)2016-09-12

Rock on! I'd be curious to see how this could be done with the derailleur system preserved on the rear wheel. I believe that shiftable gears would help increase the efficiency of the machine abs extend its range.

adamd68 (author)Tenire2016-09-21

hey mate. I have had bikes between my legs since I could stand up. Still pedalling too. I also worked in the industry for many years. So I offer my two cents.

Gears are definitely an attractive proposal, but I definitely feel that the derailleur method of achieving a selection of ratios would suffer with aggressive wear characteristics. On the chain and sprockets obviously. This will be due to the side loading of the chain as the chain moves between the different sprockets. (Ideally a chain should run dead straight from the driving to the driven cog. This is called the "chain-line") A modern 9 or 10 speed chain and cluster can wear out completely in a few 100kms of hard pedalling. Even with educated gear selection by the rider. I was renewing my chain every 3 months and rear cassette each 6 months. Daily commute on a slick tyre hardcore hardtail MTB.

Older style 6 gear cluster and chains last many times longer because the side loading is many times lower. Meaning tolerances in the drivetrain are very slack compared to the latest 10 gear setups.

Another point to note is that the application of power by the rider during gear shifting needs to be modulated precisely. If your a well instructed or observant rider. You will ease off the pedal (slightly) during shifting down ratios. And increase going up. This aids shifting smoothness. If you choose a internal hub gear system. Sturmey Archer or Rohloff for example. The selected gear won't engage until the rider momentarily halts pedalling input. This can be done so fast it is almost un noticeable. Once your used to it.

Anyways, that's food for thought. I am not saying that it wouldn't work. It will work But theses characteristics will definatly factor into the performance and reliability of such a system. If there are any derailleur e-bikes running, I'd love some stats. ☺️

I would opt for a CVT drivetrain I reckon.

Ride more everyone. ?

Tenire (author)adamd682016-09-21

Thank you for your reply.

Now that you mention it, I can see where side loading would be an issue. From the sound of it, perhaps some sort of self contained transmission would be the solution. I'd assume that's what you mean by a CVT .

adamd68 (author)2016-09-21

sexy wheels indeed. ? What kind of ranges are you getting?

ythpstrmoby (author)2016-09-11

great build only one thing i would want to add to it, and that's a way to not use a key start but a chip reader, so i could identify the rider (me) by the chip i have implanted in my hand, using this kit:

3wheels (author)2016-09-04

This is a very nice build and certainly has the appearance of "early days motorcycles".

I'm not sure that the disc brakes are really sturdy enough for a machine that can do 50MPH (80 Km) and I think I would want something 'beefier' to handle the heat generated when braking from high speed. However, as a many decades long motorcyclist, the point that gives me the most concern from your video (and I've observed it with may motorcyclists on the road, is the lack of safety clothing. Even at lower speeds, when the rider parts company with his/her machine, elbows and knees can get ground down to the bone in seconds and the feet can get shattered very easily.

Always wear full protective clothing and boots when riding, even for a short test run. The jacket needs highly reflective markers on the back because automobile drivers often don't notice the small outline of a motorcyclist and even if they do, they sometimes don't give them the space they should.

As far as your build goes... WELL DONE.

TheNecromancer13 (author)3wheels2016-09-08

I use a single front disc brake with a 200mm rotor on my gas powered bicycle, which can do about 40. It is more than up to the task and I have never even needed to use the rear brake.

dgwatson5 (author)2016-08-30

Setup a headlight, tail light, brake light, and turn signals. That should be all it takes to get it inspectable, and therfore registerable, as a motorcycle here in Texas.

etriker (author)dgwatson52016-08-30

Umm.. In Ohio and I believe most developed 48-States you must have operable pedal/chainset to meet the requirements of a nonlicensed bicycle.

But dude, I'm w/everybody else - Awesome build !!!

dgwatson5 (author)etriker2016-09-06

What makes iy desiravle to register it as a motorcycle here in Texas is that its performance would make it a good fair weather commuter vehicle for people to get to work. It's too fast to be rode as a bicycle. A moped must be registered, in Texas, if its top speed is greater than 35 mph. That's uf u remember correctly.

dgwatson5 (author)dgwatson52016-09-06

Dang typos. That's if I remember correctly.

dgwatson5 (author)dgwatson52016-09-06

Makes it desirable.

VincentV37 (author)2016-09-01

Neat Build

anjoze (author)2016-09-01

Really cool

cuyler1 (author)2016-08-31

I read the comments and they reach back some 7 years and i wondered if you still had the bike and have any upgrades been made?

JeffH95 (author)2016-08-30

That's a lovely project and very nicely done. However, as a guy who has built a number of high-speed, high-weight e-bikes, I've got to say that the current brakes on that machine as very, very inadequate. Take a look at the brakes on high-end downhill race bikes; you need that kind of stopping power on the front of the machine at the very least.

bmiller91 (author)2016-08-30

FYI I came across a direct replacement for the B&S motor

jdaniel15 (author)2016-08-30

What type of welder did you use? Or did you have a fabrication shop make some parts

Ancient Android (author)2016-08-30

Worlds Fastest Electric Baby Indian!

I love the build. The genius is the simplicity. I would've called it EV48vMarkOne.

As many suggested here you should " cripple " the beast a little. If it's possible, program your micro controller for power settings of " cool it " and " go nuts ". Then hide the encrypted activation key for " go nuts " in a safe place.

I'm not sure why and how is it that ONE could go KamiKaze on an 80cc gasoline powered bike with distance gage openly indicating suicidal speeds availability but an awesome build like this remains a taboo technology. Let's ask this question from a democratic law maker !

Looking forward to see you on the Salt Flats.

etriker (author)2016-08-30

Umm.. In Ohio and I believe most developed
48-States you must have operable pedal/chainset to meet the requirements
of a nonlicensed bicycle.

But dude, I'm w/everybody else - Awesome build !!! I'm inspired!

BradM17 (author)2016-08-30

To make your own E Bike that goes 50 MPH is Amazing!

noahfett (author)2016-08-30

Really cool! You should install a sound system on there and play some speeder bike sound effects while you ride;)

HarryP35 (author)2016-06-28

is the front wheel dual disc?whats the spoke count and where can i buy 1 from?

MatthewR13 (author)2016-05-22

Excellent idea! Love the design and everything. Have you thought about regenerative braking? If your controller has it of course.

tjacobs5 (author)2016-05-15

I would love this, but in Belgium this would be considered a motorcycle.

NoneRequired (author)tjacobs52016-05-15

It's considered a motorcycle here in the United States too, as it cannot be peddled. Since it can go faster the 25 M.P.H. in most states it cannot be called a moped (and there is still that inability to be peddled issue). Nonetheless, a pretty damn awesome build!

I'd love to know what the top speed turned out to be, and what the range is. This would make a great around town commuter.

tjacobs5 (author)NoneRequired2016-05-16

yeah just to pop into the hardware store or get a beer this would be great :D

Doc Joe (author)2016-05-15

Very nice job, you make me want to build one. It looks fun to ride as well...

JeffBlue (author)2016-05-15


Mattakadeimos (author)2016-05-15

I love the V engine layout you've gone for with the batteries. Makes the bike look like an old Indian motorcycle or Harley or something similar.

dough51342000 (author)2015-09-05

How far can you travel on a full charge. About how much did it cost to build the bike

rush_elixir (author)2015-06-30

super cool...can I copy your design? planning to do it on my mountain bike! Great design by the way!

KrisB1 (author)2014-08-19

Where did you get the dual disc hub?

WX4ME (author)2014-07-13

Great Work !!

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

the data sheet of the batteries.


mmaciver (author)2014-06-22

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.

pdub77 (author)2014-06-21

This is fantastic. You have done well, sir.

samuraijack (author)2014-06-04

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.

peets (author)2014-05-21

i bet i weill go fast on tihs 1 lol

Squidyman (author)2014-05-19

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

aetourneau (author)2012-09-19

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

They have this motor there

rjcullis (author)2013-12-13

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)?


Check out

They have Eteks there

Electric Bike360 (author)2014-02-06

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?

Eleyan (author)2014-01-30

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

rasik4 (author)2014-01-15

how about using bus or truck wiper motor(24v) for electric bicycle? what is maximum speed?

rangerweavere (author)2011-12-13

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.

About This Instructable




Bio: A Bay Area native interested in electronics, mechanics, and robotics, and automobiles. Formerly the electronics captain of Team 100 in the FIRST Robotics Competition, I ... More »
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