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Step 11: Driveline, Sprockets, and Gear Ratios!

I bet by now that you want to make the cycle go!

So, it's time to talk about the driveline.

This motorcycle is about as simple and efficient as you can get. It's more or less the same as a single-speed bicycle.
The motor has a drive sprocket, which connects to a chain, which turns the back wheel. That's it!

Drive Sprocket
The motorcycle uses a standard machine sprocket. I simply went to a farm store, which had a decent tractor repair aisle and located parts for the sprocket and chain. I bought a 14-tooth sprocket and a hub with a 7/8" center hole to match the motor's drive shaft. These are two parts, bought separately, which allows greatest flexibility in driveshaft diameter and sprocket tooth count. The sprocket and hub had to be welded together. In the earliest version of my cycle, that was the only welding done on the entire project. It was only later, when I had some welding experience that I tackled the welded battery rack. On the original sprocket, I just had somebody else weld those two pieces together for me. They were inexpensive - under $20 for both parts. If I want to change the gearing on the cycle, all I need to do is spend another $20 at the farm store and get a sprocket with a different number of teeth. These same parts could also be mail-ordered from a dealer such as Grainger or other industrial supplier.

The sprocket slides onto the end of the motor driveshaft, and is held in place by a keyway, square key, and set screws. 

Chain
The chain is #40 chain from tractor aisle. Cost about about $10 for ten feet, and a few dollars for a master link. It is a popular size chain, so there is a wide variety of sprockets that match.

Driven Sprocket
I did not use the stock sprocket on the back wheel of the motorcycle. Electric motors tend to work best spinning faster than gasoline engines, and geared down a bit more. This gives you plenty of power, without constantly running high current through the motor.
There are many on-line motorsports companies that will make custom rear sprockets. I used one called Sprocket Specialists. You simply tell them what motorcycle you have, what chain you want to use with it, and how many teeth you want on it. They custom make them on CNC equipment and send it to you in the mail.

I got an aluminum sprocket for a Kawasaki KZ440 for #40 chain and 72 teeth. It has a black protective finish. The larger aluminum sprocket weighs less than the stock steel one did. (Saving weight is always a good thing for electric vehicles.) I removed the rear wheel, unbolted the stock sprocket, and replaced it with the custom one. Consult the cycle's repair manual to make sure to bolts are torqued correctly, and that the back wheel is re-installed right.

(Somebody asked about the sprocket being aluminum, and that this is a high-wear item. The black finish on this sprocket is a wear-resistant coating. The sprocket manufacturer highly recommend at least that for protecting the sprocket. I've been very happy with it, and wear on the sprocket has been minimal overall.)

Gear Ratios
After all of my riding, I believe that I COULD have kept the original stock rear spocket. It would have given me a higher top speed, poorer acceleration, and cause the motor to draw more amps. Most of my riding is in the city, so I would gladly have a lower top speed in exchange for better acceleration and less amp draw. By having the larger rear sprocket, I can always change out the inexpensive front sprocket to change gear ratios. If I kept the smaller stock rear sprocket, I wouldn't have had that flexibility.

My current setup is a 14-tooth front drive sprocket and a 72-tooth rear driven sprocket for a 5.14:1 gear ratio. On my cycle, I'm very happy with the combination of range, acceleration, and top speed. On a fresh charge, I have just enough power to do a minor burn-out. Acceleration away from a stop for city use is very nice. There's no clutch to slip or engine to rev, so the cycle just GOES the moment you twist the throttle.

Tweak the Driveline
Once I had the sprockets on, I wrapped the chain, checked it for length, cut it to length, wrapped it on to both sprockets, and closed it up for a brand new master link. (Make sure the clip on the master link faces the right direction. It can work its way off if you put it on backwards.)

The original chain guard still fit over the new (larger) rear sprocket, but just barely. I simply bent it a tad to make sure it had clearance.

On the front end, the transmission would normally have an integral cover over the chain and drive sprocket. Without the tranny, it meant I had to make a custom chain cover. It could have been made from almost anything - metal, plastic, wood, but I wanted to show off how the cycle works, so I went with plexiglass. I roughed out the shape required with some cardboard and a pencil, and then cut the plexiglass to fit the space. A straight piece of plexiglass covers  the top of the chain. I used a scrap of an aluminum rail as a spacer between the motor mounting plate and the plexiglass to hold it in position. 

With everything in position. The chain needs to be tightened and aligned as per the user manual.

While I had the rear wheel off, I also used the opportunity to put on new tires. (Bought on sale during a close-up sale!)
<p>Ben your instructable was a huge help to me in figuring out my own electric motorcycle conversion project, so thanks for sharing! I thought you might be interested to see the instructable I just posted for my project: <a href="https://www.instructables.com/id/Engineer-Your-Own-Electric-Motorcycle/" rel="nofollow">https://www.instructables.com/id/Engineer-Your-Own-...</a></p>
<p>I've finished an EV bike of my own, however, I cannot find a drive sprocket and no guide talks about what sprocket they used. I am running an eTek motor with a 7/8&quot; output shaft and a 3/16&quot; keyway on a 520 chain, likely a common setup... what sprocket did you use? Where did you get it? My project is sitting in the garage until I find one :(</p>
Which will give more efficiency.. Series connection or parallel connection?
<p>It's not really that one or the other - series or parallel - connections are more efficient than each other. In series connections, voltage increases. In parallel connections, current or capacity increases. However, with DC motors, speed is proportional to voltage. Therefore, connecting your batteries in series is the preferred way to go. You get a higher voltage, thus higher top speed from your motor. Also, higher voltage means lower current draw for the same amount of power. Lower current means that you can use thinner cabling, which is less expensive, easier to work with, and saves weight.</p>
I'm living in an hilly area. So will a 36 volt help me.. And will it charge my battery when going down hill.. <br>
<p>The motor wont natively charge as you ride down hill. In some cases you can use a second motor to charge batteries, but it's easier to do with an alternator of some sort. Either way, though, you need a way for the whole unit to only engage when you when you are going downhill; if you don't you'll be using your drive output from the batteries to turn it. 36v may work for you, but it may not. with a hilly area you want something that is going to put out a reasonably high amount of torque (you can play with this a little bit with the ratio of your drive sprocket to wheel sprocket). Some motors (like those used in off-road winches) are super high torque, and don't spin very fast, but they only require 12v to go. Others are relatively low torque, but relatively high horsepower (which directly affects top speed) and can be 24v-72v or more. With one from a winch you could, in theory, use a gigantic drive sprocket and a tiny wheel sprocket to compensate for the slow speed of the motor. It depends on how in depth you really want to get with this build. I recommend researching the physics involved and figuring out what requirements you will need to deal with your hills and then comparing with the specs of different motors on the market.</p>
Thank you somuch mr.bennelson for your keen support for youngsters, who try to live without pollute our environment.
<p>Wow this is one of the best electric bike tutorials I've found! Thanks for putting so much detail, definitly helps a lot!</p>
<p>Looks amazing . I am trying to learn more about diagnosing issues I am having with my electric DIY cargo bike build. Should the three phase wires running from the controller to the hub carry full voltage under WOT? I am running a 48V system with a brushless direct drive rear BMC hub. Reading 54V under a full charge 15 ah battery. Reading 11.88 V at each phase wire, not changing under throttle movement. </p><p>Appreciate it !! </p>
<p>Great Build and info! I have a DIY cargo bicycle that I am trying to diagnose a failure on. If I run a 48 V system producing 54 V under a full charge should I see that on the three phase wires coming from the controller running to the brush-less direct drive rear hub as you twist the throttle? Appreciate your time ! </p><p>Donny </p>
<p>Where I live (NL) scratchbuilding anything to drive is illegal, unless you have a company that specialises in it, plus you need to give the government at least 3 models for crashtesting and safetytesting and you will have to pay for getting them recycled and/or scrapped and transport and for the testing itself, plus however many more they require but never more than 12. Motorcycle tests are fewer so maybe you can get away with only 2 or so but they will be wrecked. They will run them into crastest dummies to test pedestrianfriendlynes in case of accident and rate it accordingly. So if your homebuilt cycle fails you are done for. </p><p>Putting batteries on something also will open you up for testing for leaks and accidents, so likely crashtest to test what happens with the battery if it hits a truck.</p>
<p>is there a way for batteries of higher voltage to be used on a motor of lesser voltage where the motor will only take its recommend amount. This question is based on long distance travel where highway and city driving are necessary,</p>
<p>This is my first time on this post. I read a lot of the posts and a lot of interesting info. I have built a couple of Electric KTM dirt bikes, and am now building a Yamaha Steeel frame electric with a gearbox. A lot of the questions that every posted are good, and I have worked thru most of them. My KTM is a 2008 250SX-Fframs and running gear, a Motoenergy ME1004 48V 200-400A motor. I have been using the Kelly controller. I bought over what I needed 72V 500AMP with Regen. I am using a Magura 5k throttle and it works fine. My batteries are CALB 40AH x 16 cells to give me 48V 40AH ( about a 2KW battery pack)</p><p>I get 6 hot laps on the motocross track or 15 miles on the street, I was able to make it street legal in California since it was converted to electric. I did not modify the frame so I could put the motor back on, but I love the electric aspect of the bike.</p><p>It is on EV Albums &quot; 2008 KTM Electric&quot; under Motorcycles</p><p>To answer a few questions , the Kelly controller has been very reliable, and the Regen Braking turns the motor into a Generator, which works great on this bike. At a motocross track you rely on engine braking, with electric you don't have any, regen braking is the answer and you can program in as much in as you want, or you can vary it with a rheostat</p><p>The bike has been very reliable , and a lot of fun . It is neat have and play with it. It is encouraging to see all the people on here interested in electric build of there own</p><p>Dcoxryton</p>
Would it work if I put it all in a mini moto ??
<p>I just recently saw a Trail Buddy converted to electric. It was really cute, and an all the electric components were really well packaged. I didn't see it on their home page, but it was built by these guys. http://www.trail-buddy.com/home.html</p>
<p>You can pretty much build any size electric motorcycle you want, However:<br>1) If you build it really big, you will need a very powerful motor and high capacity battery pack.<br>2) If it's a very SMALL motorcycle, you will have very limited room in the frame for all the components, and will only be able to fit smaller batteries.</p><p>A mini motorcycle sounds like a lot of fun. You could probably get away with using the style of lithium batteries used by high-end RC Car enthusiasts.</p>
<p>I recently obtained an old 1950s Harley Davidson frame from a friends junkyard. It does not have a VIN# because this was from a time before they put VIN#'s on frames. The odd thing about it, is the DRF XXXXX number on it. Does this mean it was stolen? Will I ever be able to register this old of a motorcycle frame before I start building on it?<br><br>Thanks for any help.</p>
<p>Depending on your state laws you will probably be able build it as a new custom. My suggestion is to sell that frame to a collector and buy a complete bike with a blown motor. Old Harley frames are heavy and parts are expensive. </p>
I think the last sentence you said kind of sealed the deal for me.<br>Looks like I'll need to find a Collector! <br><br>Thanks again<br>-TM
<p>I've built a 72 volt version from a Suzuki 600 Katana. weights about 500 pounds.</p><p>This was built in about 1 week give or take a few days. the current picture is Version 3. the first version was a 48 volt 75 Ah system. Version 2 was 72 Volt 75 Ah version, but the final version was 72 volt 101 Ah version. current version gets between 30-40 miles per charge depending on driving conditions. only an estimate since it is only 22 miles to work @ 50 mph and i recharge it everyday at work, so i never really never had a chance to kill the batteries that much.</p><p>This version has a dual laptop battery pack for the light and a 72 volt battery pack for the Drive motor. all lights are custom built L.E.D. lighting that i made my self from 12 5050 L.E.D. strips.</p><p>This version uses about 50- to 65 amps at 50 mph.</p>
<p>I like your electric scooter selling service..<br>http://www.billelectricscooter.com/</p>
<p>great</p>
<p>First of all, thank you for putting so much time into such an awesome instructable! This is really helpful. Secondly, I have a question. I'm looking at doing this for a 2001 Yamaha R1. It's perfect as the engine is in good nick and the transmission is busted, but I'm wondering if it's too heavy for the electric motor you used. I'm new to EL motors and trying to make a go of it with this project. What do you think? Could it work? </p><p>Cheers!</p>
Hi!<br>Put in few words, with same motor and more amps-hour (more energy stored), go farther.<br>Readequate motor (to get more power - more watts), more amps-hour, more speed depending on gearing. Same range. It's not so simple, you have to equate all variables for your goal.<br>Usually motors with higher voltage can develop more power.<br>Of course the correct is that you have a target power, say 750W (~1 HP), for sake of simplicity: 75V x 10A to feed the beast. Or, 32,5V x 20A. Or 150V x 5A. And it goes on. Higher voltage also allows thinner wiring (to hold less current)if you manage to have a motor that runs this figures at 12V, you would need to provide 62.5 Amps. Imagine the wiring for this now. Research motors, batteries, weight, your goals and spreadsheet it to find your personal solutions having in mind what you want. :)
<p>Wow what A dream bike..<br>I want to build my own like yours. <br>does it become a 96v18ah battery if i connect two 48v9ah batteries?<br>This is what I found on alibaba website </p><p><a href="http://www.ebike-bmsbattery.com.cn/product/690588130-215068276/e_bike_48v_lithium_ion_battery_ups_battery_48v_lithium_ion_battery.html" rel="nofollow">http://www.ebike-bmsbattery.com.cn/product/690588130-215068276/e_bike_48v_lithium_ion_battery_ups_battery_48v_lithium_ion_battery.html</a><br>Lifepo4 48v9ah E Bike Battery,e-bike battery,ebike battery<br>Item No. Voltage Capacity battery type Lifespan <br>BMS<br>Option<br>Charger<br>Option<br>Dimensions Weight<br>G-BP4809A 48v 9ah lifepo4 <br>&gt;2000<br>cycles<br>15Amps 3Amps 69*148*360mm 4.9kgs<br> <br>48v 9ah electric bike li ion battery Characteristics<br>a. Very Security: No fire,no explosion,no leakage ;<br>b. Portable handle and hidden charging port;<br>c. Aluminium alloy Back rack(Silver and Black for option);<br>d. Well die-casting slide board and lock, for easy installation and theft-prevention.<br>c. 30A Fuse and smart BMS are included for protection<br> <br>Pictures and detaild data sheet</p><p>Model G-BP4809A<br>Norminal voltage 48V<br>Rated capacity 9Ah @0.5 C3A, 20&deg;C<br>Operating current 15Amps(can be customized) <br>Peak current 30Amps(can be customized) <br>Charge voltage 58.4V <br>Standard charge current 3Amps <br>Cycle life &gt;2000times <br>Dimensions 69*148*360mm<br>Weight 4.9kg<br>Battery box material aluminium alloy <br>Built in battery cells 3.2V 9AH polymer lifepo4 cells <br>Assembly 16 cells in series<br>Operating temperature - 20 &deg;C to 60 &deg;C<br>Charge temperature 0 &deg;C to 45 &deg;C</p><p>it weights about 12 pounds.<br>What do you think? No one can answer my question.</p>
<p>Hi.</p><p>Batteries Voltage adds up when in series, but current does not. If you put 2 batteries in parallel, you will get same voltage but will add the current. This is very very basic electricity.</p><p>To achieve your 96/18 figures you need 4 batteries, putting 2 pairs of 48/9 parallel batteries in series. I mean take a pair and mount in parallel - call it now pack 'A'. You now have a 48/18 pack. Then take 2 of this packs 'A' and put in series then you have your 96/18.</p><p>Best regards</p><p>Lissandro</p>
Thanks. Sorry for bothering you but if you dont mind i ould like to ask you one more question. Would my bike run faster and run farther if only current(AMPS) goes up? I think there is extra space for a pair. in that case a pair becomes 48v/18ah?
<p>No, current has nothing to do with range or speed. On a DC system, speed is determined by voltage and gearing. RANGE is primarily through battery CAPACITY, which is measured in AH - amp-hours. Being able to draw more current can get you to your top speed quicker (better acceleration) but won't change the top speed.</p><p>If you add additional batteries in parallel, this will increase the capacity of the pack, and give you better range. Current is only related to range in that batteries will give you less total range at high current than low current. Also, if batteries are the limiting factor in how much current you can draw, adding more in parallel will allow you to draw more current. </p><p>Remember that current (measured in amps/ampres/A) is flow, it is a RATE of power use. Amp-Hours (AH) is a measure of capacity. </p>
<p>Questions:</p><p> 1. Why a drive between the motor and the wheel? Why not have the motor in the wheel hub? Wouldn't this be more efficient?</p><p>2. Do you still use a gearbox? If so, why? Cant you use direct acceleration?</p><p>3. Why have a braking system, once the vehicle is stationary, wont it only move if you apply power?</p><p>4. Could you use this same system to make an electric cruiser?</p><p>5. Where can i get an high efficient high speed motor?</p>
<p>Hi Alexander!</p><p>Answers:<br>1: Chaining the motor to the back wheel allows for both adjustable gearing (by changing the sprockets) and for placing the motor where I would like it. Hub motors of the right power ARE now available for motorcycles, but have not always been the best thing for high top speed. Direct drive also doesn't usually give you the same &quot;oooomf!&quot; that you can get with a chain drive. Also, a hub motor increases &quot;unsprung&quot; weight, which isn't as good for handling. My project as of spring 2015 is a Vectrix, which DOES use a rear hub motor, but it also has planetary gearing to overcome some of the limitations of hub motors.<br>(http://300mpg.org/2015/03/02/vectrix-maiden-voyage/)</p><p>2: Please see step 11. <a href="https://www.instructables.com/id/Build-Your-Own-ELECTRIC-MOTORCYCLE/step11/Driveline-Sprockets-and-Gear-Ratios/" rel="nofollow">https://www.instructables.com/id/Build-Your-Own-ELE...</a> It clearly shows that there is no transmission. The motor is chained to the rear sprocket. Yes, it is more efficient than with a transmission, there's fewer moving parts, it also saves space!</p><p>3: Brakes! Yes, of course I have brakes! The cycle came with brakes, I did not change them. Why would I want to remove the brakes! Yes, once at a stop, the cycle doesn't move, unless on a hill. Brakes are most important when you are moving and want to slow down! The vehicle doesn't have &quot;regenerative braking&quot; or any special system other than the stock regular motorcycle brakes.</p><p>4: Yes, you could build an electric motorcycle similar to the say I did, but build it as a standard, a cruiser, a sport bike, a scooter, or whatever style of motorcycle you like. Sport bikes are popular for conversions because of their light-weight aluminum frames.</p><p>5: There are many mail order companies on the web that sell electric vehicle parts. Just do a web search for them. The Electric Auto Association also has some nice links on their web page. <a href="http://www.electricauto.org/?page=EVsForSale" rel="nofollow">http://www.electricauto.org/?page=EVsForSale </a> Scroll about half way down on that page to &quot;EV Converters, repairs, &amp; kit or component suppliers&quot;, you can order parts, including motors from those places.</p>
<p>Dear Ben,</p><p>I have a 1972 honda dirt/trail bike whose engine seems to me not worth restoring, and I have toiling with the idea to convert to electric for the longest time, refreshing my parts wishlist from time to time.</p><p>At last I've seen the Enertrac 18&quot; hubmotor, and its the ideal motor in my opionion. However, as with any electric application, battery technology seems to let us down in various combinations of cost, weight, size, and amperage (cost in particular). </p><p>I have seen your batteries on your Kawa and its damn huge (and heavy). I am thinking of using LiPO batteries from hobbyking (those used in large scale electric RC) - just need your two cents on this opion.</p><p>Tks,</p><p>Aszman.</p>
Hi ErfanA1,<br><br>Yes, you are right, lead-acid batteries ARE heavy. In fact, right now, I'm upgrading my Kawasaki to NiMH batteries I got out of an old Ford Escape Hybrid! (Nickel is still heavy, but it's better, and the salvage yard price was GREAT!)<br><br>Hub motors are becoming practical for EV motorcycles, and have already been used on many EV Scooters.<br><br>Lithium batteries are great. You might want to see about going on the Endless Sphere web forum. Those guys are into electric bicycles, but have GREAT knowledge to share about using small lithium batteries.<br><br>Good Luck!
<p>SUH-WEEEET-AH!!! </p><p>So 'ok...you've got the info I needed and explained clearly...more clearly /less cluttered than most other related instructables! Now can you answer me this...the wires coming from the controller to the throttle.....could an arduino replace the throttle? this would be for remote or programmed motor &quot;control&quot; ie: instead of a human hand turning a physical throttle...an arduino sending signals to the controller as though it (arduino) IS the throttle...? make sense?...others have jumped all over me for this...but I think the 2 wires can act as the potentiometer..? yeah?</p>
On my motorcycle setup, the throttle is a 0-5Kohm twist potentiometer. To replace this style throttle with an Arduino, you would need the Arduino to be able to create a variable resistance in that range. I haven't played around with Arduinos very much at all and would have no idea how to do that, but I'm sure somebody could figure it out.<br><br>There are also motor controllers that use a variable voltage of 0-5 volts as their input. Voltage can be varied by PWM, and I know that can be done by Arduinos. So, it may be an easier approach to use a controller with that style input.<br><br>Due to safety considerations, I would NOT create any kind of &quot;experimental&quot; throttle for an on-road vehicle, but if it is for some sort of stationary machinery, just follow typical safety precautions and have fun!
<p>YES!! thats the numbers I was lookin' for!!! I'm just starting arduino as well but, if I'm not mistaken 5v is exactly what the arduino needs /handles.</p><p>I'm sure a resistor or two would make it a little safer I think? arduino pros?</p><p>the applications of this could be for giant remote control cars, a stationary sculpture...anything an arduino could influence via...PIR sensors..bluetooth phone remote control...timers etc.</p><p>Much Thanks Bennelson!!</p>
<p>I have lots of bikes but I have this 74 cb 360,I took this cbr 600 that I had ,it was from a police chase and it was never picked up from the cops after its rider got away after it slide own on a golf course so I got it after it sat at the tow company for a couple of years..never could get a title for it so I sold its engine and took off its rear swing arm and front forks which bolt directly ODDLY to the 74 cb..I welded on the rear swing arm to make this cafe bike....but Id like to convert it to electric since I have 3 more bikes including the 75 cb 550....which will be cafe also but still a gas burner..I want an electric motor that goes faster than 45 mph..any suggestions?Im going to run lithium batteries Im thinking.</p>
For high speed/performance, it's best to go with the highest voltage motor you can. 72V is pretty popular for a fun lithium bike. Motenergy has some good motors. Check them out.<br>http://www.motenergy.com/
Can you use the existing transmission system of the bike??
On most motorcycles, the engine and transmission are really a single, integrated unit. It's very difficult to remove the engine, but keep the transmission. You CAN build an electric motorcycle with a transmission, but the tranny takes up space that might better be used by having more batteries. <br> <br>What a transmission in general really does is convert engine speed into torque. Electric motors tend to have HIGH torque at LOW speeds, so you don't neccessarily need a transmission. <br> <br>For a commercially-built EV cycle WITH a transmission, take a look at the Brammo Empulse.
<p>How about getting hold of an old pre-unit Triumph (or other manufacturer) gearbox? They are small and lightweight and also very strong mechanically. You should also be able to get different gear cluster set ups at a reasonable price.</p>
But couldn't you gear that high torque down to get better top speed/further range?
For higher top speed, you would use high gearing, which would pull greater amps. Pulling higher amps creates more heat, shortens battery life, and reduces how far you can go per charge.<br><br>In general, to increase top speed, you are best off increasing your system voltage.
<p>Good day Sir, i would like to ask if this bike could be build in South Africa too, and if i may request the plans for this bike please. Would you consider to open a factory here in the RSA ? A lot of jobs can be created by this and you may profit a lot by it too. My email is just1info@gmail.com 073 327 9390 thank you very much.</p>
<p>Good day Sir, i would like to ask if this bike could be build in South Africa too, and if i may request the plans for this bike please. Would you consider to open a factory here in the RSA ? A lot of jobs can be created by this and you may profit a lot by it too. My email is just1info@gmail.com 073 327 9390 thank you very much.</p>
<p>Good day Sir, i would like to ask if this bike could be build in South Africa too, and if i may request the plans for this bike please. Would you consider to open a factory here in the RSA ? A lot of jobs can be created by this and you may profit a lot by it too. My email is just1info@gmail.com 073 327 9390 thank you very much.</p>

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