Electric Motoped - Advice Needed


100 µW
Mar 6, 2016
Electric Motoped - Advice Needed

I am planning to add an electric motor to my Motoped. I have most of the build planned out, but before I get too deep into the details I thought I'd ask whether everything seems reasonable, and if anyone has any advice.

Here is my situation and my goals:
Bike would be mostly used for commuting, 4 miles one way.
I'd like to try some occasional dirt/trail, and possibly light track riding (Sonoma kart track).
I live in San Francisco at the top of a large hill, ~10% grade and 1-2 miles top to bottom.
I'd like a minimum top speed of 60mph. I may not go that fast often, but I'd like the option.
I want the maximum possible acceleration for my weight/cog/wheelbase, enough to powerwheelie.
Smooth throttle/acceleration at low speeds is very important to me. My current motorcycle is very jerky at low rpm/speed and I don't want to deal with that any more.






It was made to accept Honda 50/70 pit bike engines like this:

If you can't tell from the pictures, the motor would be connected by chain to the jackshaft on the swingarm pivot, which is in turn connected to the rear wheel. I should be able to change the rear sprocket fairly easily and I'm thinking I should go as large as possible (50-60 teeth) and adjust the total reduction via drive sprocket.

For power, I found the following site that talks about the torque required to wheelie:

wheelie torque = mass bike * g * wheelbase / 3 * sin theta + weight rider * g * wheelbase / 9 * sin theta
mass bike - 60kg
wheelbase - 1.32m
mass rider - 90kg
torque = 286 ft lbs
Hopefully this should be achievable, see below.

I have some very basic wrenching and soldering experience, but most of the skills and knowledge required for this project are new to me so I've been doing a ton of reading. Here is the plan so far:


After lots of reading I narrowed the choice to a few motors, and am 95% sure I've made my decision:

Revolt 160 Pro - High claimed power with low claimed weight. There are a few examples of successful builds with this motor, and the smaller 120 version. There isn't too much performance data, and I've seen speculation that it's overrated for ebike use as it was designed for aircraft and couldn't have sufficient cooling at it's rated power. To control it the best options appear to be Addapto or Kelly. Mounting this to the bike would be challengine. I'm not sure to what extent this would need to be enclosed/protected. From what I've read, programming the controller to work with the motor may be tricky, and hard to dial in. I've also read some people have very long delays in receiving the motor.

QS205 - Tons of successful builds, reliable, heavy, easiest mounting, not great for hills, lots of controller options. Good weatherproofing.

Hubmonster - I reached out to John in CR for some information looking to buy a few months ago, but he was very busy, and now it looks like this is no longer for sale.

Motenergy ME1114 - Reliable, heavy, powerful, Sevcon a nightmare to program (possible to use Kelly?), very wide. If I went with this I'd buy it preprogrammed from somewhere like Electric Motorsport.

Lynch LEM 200 127D, Saietta 119R - This is the motor I'm fairly certain I will choose. Thin, relatively high power, cheaper/easier controller options, reliable, many successful projects, smooth acceleration and lack of cogging. I tried emailing Saietta asking about price/availability of the 119r but did not receive a response. I can buy the LEM motor from Cloud Electric.


Brushless - Adaptto/Kelly/Sevcon - I like the Adaptto due to it being an all in one solution, although it's limited to "only" 14kw. Sevcon seems to be very robust, but from what I've read programming it seems to be beyond my abilities. Kelly has mixed reviews, easy to program, good support, poor acceleration, questionable reliability, not capable of rated current.

Brushed - Alltrax SPM - I believe this is what I will go with for the Lynch motor. Reliable, easy to program, good support, speed and torque throttle control. Lynch recommends the Brusa MD95, but that is impossible to find, and it's not clear how old that recommendation is. Was it made before the SPM was released?


I'd like a range of > 15 miles, so according to most calculators I need at least 20AH. To supply the motor with its maximum current I will need a battery capable of providing 200A continuous and 300-400 burst. This seems to rule out most 18650s (would be too large to keep the C reasonable). This leaves me with RC Lipo, A123 LiFePO, and Nissan Leaf cells. I believe I've read enough about RC Lipo to build and pack and use/charge responsibly, but it seems like more babysitting than I want to deal with.

I made a google doc with some price/quantity/power/etc. calculations:

It seems like 5 Leaf cells rewired to 4s1p may be the easiest, albeit a little heavy solution. The A123 20AH pouch cells look like the most attractive solution to me, but will require some more research on how to set up properly. I know these don't have the best AH per kg or per $, but they are actually very close in cost to to the RC Lipo (assuming the RC Lipo should only be run at 1/4 of rated C). A ES member used to make and sell kits for these, but I believe they stopped making them.

I'd appreciate advice from anyone who has used the A123 pouch cells. Also, where is the best place to buy these. Is buya123products.com an official/reputable site? I read that A123 sells factory direct, is this the correct site?


I am undecided on BMS, more research is needed. Any advice would be welcome.

Motor Mount:

I have been learning Sketchup to model motor mount brackets. I created a cardboard model of the LEM200 to make sure it would fit in the frame, and then created the following model:





Orange - Motor
Blue - 10mm mounting plates. I'd need to get these made by someone like emachineshop or bigbluesaw. Could I use aluminum, or would steel be needed?
Yellow - Standoff spacers, I can buy the size I need from https://www.unicorpinc.com/metric-male_to_female_standoffs.htm.
Green - 100mm unthreaded spacers, I haven't found anyone that makes a 100mm spacer, but I'm sure I can find some generic pipe of the right size somewhere.

As for modeling the actual bike itself, it's beyond my current abilities. Someone on the forums here has a model made already, I sent a pm but haven't heard back yet. Does anyone know of good a free program that can turn photographs into a 3d model?

I am not an engineer and have many questions about mounting strength/requirements and would appreciate feedback. There are only four intended mounting locations on the frame. These points are within 90 degrees of each other which does not seem ideal. Is this design strong enough? If not, perhaps I could add another mounting point on the battery box on the other side, which I have yet to design.

Any thoughts, advice, feedback, critiques would be much appreciated!
I've always wanted to put one of these liquid cooled motors on my Motoped, just so that I could stuff a couple of little aluminum radiators up under the plastic shrouds like a real mx bike. http://www.goldenmotor.bike/categories/bldc-motors/
Water pump could be one of the TAG racing kart type driven off the rear axle with a rubber o- ring only mount and drive off the Motoped jackshaft. I'm running mid drive 6kw hub motors now and mine will climb the steepest hills but topspeed is nowhere close to 60mph. I will be watching your build with great interest.
Some progress:

I decided on A123 20AH cells 24s1p. I emailed both OSN in China, and the official supplier a123batteries.com with questions. Buying from A123 is $19 more per cell, but shipping is $250 less. So It's only $200 more total, which I think is worth it for peace of mind. To be fair to OSN, they were very responsive and appear to be selling genuine new cells. They said the date of manufacture of their cells is 2015.

I contacted forum member agniusm regarding his battery assembly kit. Although he no longer makes these, he fortunately had enough parts remaining to put together a kit. It's in the mail on its way to me now. He has been super helpful and I'm very appreciative! I'm a bit worried that the 24s pack will be a bit wider than I'd like, but I've committed to it for now, and can change to two 16s packs in series later if needed.

I emailed both Saietta, manufacturer of the new Agni 119R, and Cloud Electric, US distributer of the Lemco LEM200 127D. The Saietta is (supposedly) a slightly improved design, is cheaper (thanks Brexit for the exchange rate bonus!), and has cheaper shipping (UK -> California is somehow cheaper than Oregon -> California!) so the Saietta is a no brainer.

Still to do:

BMS - I found this BMS while browsing the forum:
It appears to be the successor to the well regarded Founding Power BMS:
It looks like it has everything I'd need, but I'll need to do some more research on how to wire it properly.

Charger - I am leaning towards an Elcon charger. They seem to be well regarded, and are local to me if I ever have issues. This site seems to sell them cheaper than most:

Mounting - I made a cardboard model of the motor and brackets from my sketchup designs. I did a test fit and it looks good. The next step will be to make a more precise model out of something stiffer than cardboard (plastic cutting board maybe), then measure that precisely, and make a final cad model based on that and send it to emachineshop.

Misc wiring/relays - I need to learn more about proper wiring (gauge, relays, fuses, shunts, etc.)
I ordered the batteries directly from A123. I also ordered the motor! I went with the LEM200-127D. Next up will be the controller from Alltrax.

I started working on a wiring diagram. These types of electronics are new to me, so I'd appreciate any feedback. Please let me know if I'm going to blow something up!



Motor should be on its way. Fedex attempted to deliver the batteries today but I wasn't home. Fedex wouldn't hold it at the post office for me, they said because it is hazardous material, they MUST deliver it to my home.

Emsiso responded regarding the 2405 controller. They were even gracious enough to point out a few mistakes in my wiring. I think I have it right now, but I'll probably try to hire Jozzer and Frodus for consultations to make sure everything is correct.


Trevor at LMC pointed me to an interesting device to help control throttle response:
Digital Torque Control Module DMMD
I understand the open loop, but I'm not quite sure I understand how it works in closed loop mode. Is there a more elegant solution for the 8 possible combinations in open loop mode than 3 handlebar switches?

That company, Pico Amps, also sell a few other interesting Lynch motor accessories. The "speed boost" brush advance mechanism looks really cool.
This is going to be great. Attention to detail is always a winner. When you assemble your kit let me know, I will need some dimensions, I have a proposition for the box to apply some compression.
I've been busy with holiday stuff and haven't had much time to work on the bike. I've received a few parts, and ordered some random odds and ends, but I still need to make decisions for major components including BMS, charger, DC DC converter, and contactor.


I'm considering an Emus BMS, which uses distributed cell boards. Unfortunately that means I wouldn't need to use the convenient jst plugs already wired into agniusm's kit. The boards are to big to mount flat, so I'll need to mount them vertically. I bought a brass strip at the hardware store, cut, bent, drilled, and tapped it to test a mounting method. Would this work? Would the connection be good enough? I'm assuming the balancing current of <1A wouldn't be a problem. I need to get a drill press!

Excellent work!!
Excellent components choice.
I too have a motoped that I am making electric.
Going with the same motor and Alltrax 7234 controller.

Advise: While making the battery. Tape those exposed battery bars with plenty of tape when making the battery or you will have some serious fireworks!!
Take off your ring and don't wear a watch.

Cutting the A123 Tabs. Do not reach across the battery tabs to cut them. Cut one tab then flip battery over. Then cut the other.
Do not cut the tabs 1 after the other like cutting chrismas wrapping paper. To much of a chance of the scissors making contact with the tabs and causing a short.

I would skip a bms.
Monitor the packs while on the bike with a lipo monitor. Balance charge them with a hobby charger when they go out of balance.

How do I know all this battery stuff? I have helped make an A123 20ah 30s1p for the solar car team that I am an instructor for at school.

Can't wait to see more progress specifically on the motor mount. I would be interested in purchasing a motor mount after you make it. If you are going to have it made by a machine shop PM me before you order it. I would be interested in buying one or splitting the cost of having 2 made. One for you and one for me.
Here are some pictures of the motoped that I am converting.


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Hey, have you managed progress on your build? I am building/converting a go-kart and also looking at Saietta brusless motors, I emailed them, but still waiting for reply. Have you had much luck talking to them?
Did this e-moto-ped get built? Looks like a lot of the money was spent and the project was started. I'm curious to hear how it turned out! Also, did you ever have a gas engine in the bike? If so, how did that compare to the electric?