Modern boardtrack-inspired cruiser build

Dec 4, 2013
Hudson, New Hampshire USA





Heres some update pics, just need to weld the torque arms and a bracket for the rear avid bb7 mechanical caliper. Also still waiting on my 72v frame triangle battery from em3ev which is being custom configured by Paul(cellman) and lastly need to swap out the bottom bracket. This bike started life as a micargi steel frame single speed.

Motor- Crystalyte HS3540
Wheels- Choppers US 3" dual wall aluminum
Controller- Infineon 72v 40A
Computer- CA3dp with temp sensing
Brakes- 160mm front and rear avidd bb7 mechanical disk
Seat- Brooks
Torque arms- Doctorbass
Battery- (yet to receive)72v 14Ah frame triangle samsung 20R cells
Tires- 2.5 in maxxis hookworms, kenda DH tubes, tuffy tire liners

Cant wait to ride it :)
I purchased a very nice road bike that ive been riding quite a bit so it hasnt been all that bad.


Hello everyone,

A few months ago I read an article about Audi's new electric bicycle capable of 50 mph and I just couldnt believe it. I did some digging and stumbled upon this forum and also I was amazed by some of the bikes people were building on slim budgets. Instantly hooked. It was time for me to start thinking outside of the transportation box and build something different:

My plan is to build a modern boardtrack inspired bike capable of a cruising speed of 35 mph, rear hub direct drive motor, with a temp sensor, front and rear disk brakes, a lifep04 lithium battery and a cycle analyst. I chose this steel frame cruiser made by micargi as a starter for a few reasons.

Untitled by danjpendleton, on Flickr

Untitled by danjpendleton, on Flickr

Untitled by danjpendleton, on Flickr

Steel frame- Heavier, but more rigid and overall pretty good durability. Plus, I can spread the rear drop out a bit if necessary for the hub motor. Which will be very likely.

Motorcycle triple tree front fork- Mainly because it has a tab for a disk brake caliper, still deciding whether i should go mechanical or hydraulic. I almost went with a springer front because it has a more vintage look and because i know of a source that sells springer front disk brake caliper adapters. This would have been more costly and I think the triple tree will add to the modern look. Plus it came on the bike from the factory.

Wheels- are 68 spoke so ill have to ditch those, but I might run the 26x2.125 tires that the bike came with.

Seat- will need to be modified to achieve the look i want and ill probably ditch the seat for a brooks saddle.

Bars- I bought some sweeping cruiser bars i was going to flip and trim, but the center that gets clamped is too fat. The ape hangers need to go :)

Gearing- I went with a single speed to simplify everything. I plan on purchasing a latger chain ring to keep up with the hub motor at higher speeds.

Originally I considered a stretch cruiser, but Im glad I didnt get one. They are entirely to big and cumbersome. This bike is perfect for what im trying to achieve and it will fit in the roof racks with ease. Plus i can drag it up some stairs and into an apartment if i ever have to store it at a friends. My other consideration was a 4-stroke motor kit. Nh requires a motorized-bike registration now and theres a lot of confusion around legislation. too noisey, too much attention from cops and the opposite, and frankly too much like a motorcycle.

I found two of the same bikes on with 2 stroke kits that share a very board track inspired look to them:

FxCam_1370890553178 by danjpendleton, on Flickr

036.108131423_std by danjpendleton, on Flickr

I really like electric bikes because not many people are familiar with them. They are cutting edge and just downright cool. As battery technology improves I feel like more and more people will see their potential as reliable commuter vehicles. I know a lot of people already have. I still have a lot of planning to do, but I wanted to introduce myself to the forum and start a build thread in the early stages. Im very optimistic about this project and cant wait to get the ball rolling. I will post up some more info very soon and look forward to hearing from all of you.

Thanks for reading.View attachment 1


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What is the expected average commute for the bike? do you have steep hills on the way? Flatter terrain allows many options, and steep terrain narrows options down. What top speed do you want?
My commute is roughly 14 miles each way. As you can see it is relatively flat with a few hills, nothing really steep. Id like a steady cruising speed of around 35 mph. i can charge the bike at work. Im going to try to budget where I can, but im not afraid of investing money in this project. Its going to end up saving me money in the long run
Boardtracker bikes,parts,and inspiration at Oh, I wounder if mid-drive hub motor could go in this frame.
i want to stick with a dd rear hub motor for this particular bike but the frame is quite big, so im willing to bet you could set it up with a mid drive hub.

I think 72v is the magic number on this thing. I considered the 48-50v battery that em3ev offers but from what ive read its not going to cut the mustard.

Id like to stick with LiFePo4. I know the discharge rate of LiCo is phenominal, but Id rather stay away on my first build.

I was thinking of maybe running 2 36v batteries from ping or em3ev. Or just contacting them about configuring a custom single 72v.

Id like to mount the battery rigidly to the frame and have put a lot of thought into how I could do it without breaking out the welder and having to grind and repaint the frame of the bike.

Derringer is a company that puts small displacement honda engines on cruiser frames with boardtrack styling and fancy paint jobs. Ive heard mixed reviews. Either way they are pretty cool. They make an ebike too.

So it kind of dawned on me that a moped style gas tank would be an awesome place to house the battery and maybe even a controller if possible.

Heres just an example. I could probably just cut an access door on each side with keyed locks. Just food for thought. Ill have to contact ping or em3ev.
Welcome! 35mph will eat a bunch of voltage,gas tank will be small.just keep lookin around here you will see what you need you need to take battery in while at work?
im wondering if a cromotor would be overkill. Ive heard mixed reviews on the new clyte motors. The crown is a possibility. Ill have to weigh the bike and jump on the scale as well. That way i can use the simulator to get a better idea of what ill need.
agniusm said:
I think thick leather battery case would be most appropriate for such bike, brown for sure to go with Brooks.

Ive seen two very nice ones before. I think they were both on turn-key production ebikes. pretty sure i have pictures of both of them on my computer at work. Ill try to dig them up.

I considered that possibility and really like the look. I could even have my younger sister make one for me(fashion school).

I liked the idea of a rigidly mounted battery so I could leave the bike outside a store locked up for a few minutes without having an anxiety attack, but I ride with a backpack most of the time regardless.

I suppose I could just throw the battery and bag in my backpack when need be.

I want to hone down and pick up my battery setup sooner than later. I dont want to go with lico/lipo

Id prefer a ncm or lifepo4 setup. I know the a123 cells pack a punch. I dont think em3ev uses a123 lifepo4 any more, but they claim their
Samsung ICR18650-22P are just as good. I read that they arent ncm, but lithium cobalt rechargeable.

To be honest i dont really care, just want to make sure the battery i do end up with can handle the job.

Any suggestions for a triangle frame setup other than the 50v em3ev one? Anyone have one? Not quite 72v but maybe it will do the job?
Okay. I emailed ping about a custom configuration 72v Lifepo4 battery. They promptly responded and said that theyd be willing to work with me if i emailed them some dimensions. 8)

I think the bike will be cooler if i can configure the batteries in the frame triangle somehow. I was lurking on the forum and found : migueralliart

he found a company to laser cut an abs plastic housing for his batteries. pretty neat if you ask me. i guess the total price was around $80 bucks. not bad at all.

----Ping also told me that I could use (2) of their 36v batteries in series instead of their single 72v, but I would need two seperate 36v chargers. Might be a more economical way of doing it. Id like around 20ah, maybe 15Ah at the very least. I know that wiring cells in series to achieve 72v and then wiring the rest in parallel will increase the overall capacity of the battery. not sure if i have enough room for the frame triangle to achieve 20ah. but just for shits and giggles:

I figure I run the 72v 20AH battery with a 50 or so amp controller= 2880 watts roughly?

The discharge rate of a 20AH battery(LiFePo4) is usually around 60 amps? (if the c-rate is around 3)

The battery should provide about 1440 w/hrs of energy?

So if Ive done the calculations correctly, with a hs3540 which can handle around 3,000 watts, will my setup be up to the task?


this is a 36v 15ah battery i found that uses headway cells, which have a higher discharge current than standard lifepo4. it says to email them about custom configurations, so im assuming they could wire 2 in series.

would i need a higher discharge current than lets say 3c in my case?

*i think might be affiliated with
ive decided to go with a clyte hs3540 dd sensorless motor.

As for the controller im leaning towards the the infineon controller that sells.

its a 40amp 12fet with an operating range of 36-72v. should be a direct plug in with a v3 cycle analyst that features a temp sensor.

It has a current limit of 40 amps.

Im trying to figure out whether i should shoot a bit higher and use a lyen controller. Just trying to iron it out in my head
I recommend getting the hall sensors in the motor. You don't have to use them, but they don't cost any extra. A motor with halls can just have the halls unplugged and run with a sensorless controller, but it's a good option to have.
If you are running with the halls hooked up, and then you get the motor too hot...the halls can fail, usually just one of them. Millions run with the halls every day and have no problems. Some builders have a smoother response with the halls, some prefer the ride using sensorless.

If you don't have halls, you have no choice. Just for the record, I suggest that every E-biker have a 6-FET sensorless controller as a back-up, plus a digital volt-meter, and a spare throttle. With those three items you can trouble-shoot 90% of common problems in just a few minutes. The primary controller should be whatever you determine meets your goals.

If you are feeling ambitious, add a temp sensor. The 10K thermistor is the most popular, because it can be hooked up to a CycleAnalyst to access all the features (temp data-logging, amp roll-back at warning temps, amp cut-off at danger temp, etc). The LM35 sensor reads the temp as a voltage (0.80V = 80C).
plan on getting the temp sensor. Multi-meter i have. Good tip on the throttle and backup controller. ill get the halled motor and go sensorless for now. that way if i do ever switch to sensored controlling i dont have to ditch the motor

ok let me pick your brain.


Motor- dd clyte hs3540 (definite)

Controller- 40amp infineon or 50+amp lyen

Battery- 60v 15Ah 20s lifepo4 w/ headway 40152 cells
48v 20ah a123 cell pack
72v 20ah a123 cell pack

Basically what im trying to figure out is what real benefit id be getting with a higher voltage battery if my controller is limited to 40amps?
just overall speed correct? Because the total output of the motor is limited by the amount of voltage/current it is fed?
The HT/HS designation just refers to two different Kv's. The Kv is (roughly) how many RPMs you get per volt.

It's less good to have a very high speed hub system, and then run it at half-throttle all the time. Choose the lowest top speed that you can be happy with, and then choose the highest voltage pack that you can afford, and also fit on your bike.

Then, choose the model of motor with the minimum copper mass that can handle the amps you want to use, and then the Kv of that model that provides your design top-speed at the pack voltage you chose. As a rough guess (from reading a lot), the Crystalyte H-series seems to be good for 40A peaks and 25A constant. Maybe use the simulator at for an HT at 72V, see what you get?

edit: Direct-Drive hubs (DD) seem to respond well to oil-cooling, maybe an option...
Not much progress with xmas and all however i did pick up some relatively straight bars that bend slightly back. i got them for free and i think the powdercoated black finish on the bars match the bike nicely. also mocked up the laidback seat just to visualize the look. Sportsman makes the post i need for around $30. I Plan on purchasing a nice aged leather brooks saddle as well.

still trying to decide between an em3ev battery or a bmsbattery. The bmsbattery is 72v 15Ah 40152 headway cells
$649 plus shipping
Cheaper....decent cell composition and good crate. just dont really know about that particular vendor???? Anyone purchase batteries from them and have good results?

The em3ev 75v battery is 20Ah w a123 pouch cells
$1050 plus shipping !!!!

pretty steep but a bit more capacity and a higher c rate. I dont really want to spend that much on a battery

I plan on running a 40 12fet infineon controller and a clyte motor