Hi! My name is Luke and I built a really fast electric bicycle that I also use as a replacement for my car! Don't worry if you don't know much about bikes or electronics...I don't either. I'll do my best to make this Instructable readable for everyone that's interested.
What is an E-bike, you ask? It's a regular pedal bicycle that has been converted to be driven by an electric motor. The motor can either supplement pedaling or drive the bike by itself (like an electric motorcycle that happens to have pedals). This will be discussed in more detail in the following steps.
Here are some quick stats on this project before we get into the details.
- 50+ mph top speed
- 8-speed transmission
- Ludicrous acceleration
- I don't have any numbers on this yet, but full throttle in a low gear will easily pick up the front wheel (i.e. it does wheelies)
- I haven't found any local cars or motorcycles yet that can beat me in a 0-30mph drag race.
- Super light weight, around 55 lb (with motor, battery, etc)
- 700c x 40c tubeless cyclocross tires
- Rockshox air suspension
- 180mm mechanical disc brakes
- $800 Battery
- $550 Bike parts
- $400 Motor
- $300 Motor Accessories + Upgrades
- $150 Misc Parts
- Detailed parts list
Step 1: Motivation
So, why build an E-bike? Brace yourself, this is the boring section. Feel free to skip it and move on! If you're here for the long haul, here are the main reasons that I decided to pursue this project.
- Ease of commute
- I have the pleasure of living in the beautiful town of Fort Collins, CO.
- Almost every single street has a bike lane, and tons of people bike for pleasure as well as to commute.
- Roads can get pretty crowded, and parking is always tough to find.
- An E-bike presents "the best of both worlds"
- I can commute anywhere within a fairly large radius around town, usually faster than a car.
- I can park at bike racks (which are absolutely everywhere and in less demand than parking spots).
- Gas Savings
- My only car is a big truck that gets 17mpg on a good day (and 13mpg on not-so-good days).
- An electric bike is suitable for 95% of my transportation and is essentially free - I can charge it anywhere there's an outlet.
- For the nerds out there, I get the energy equivalent of ~80mpg on the bike.
- I carry large panniers (bags) on a rear rack so I can go grocery shopping, carry around big boxes, etc on my bike.
- No Tired Legs
- I'm currently training for some elite 5 and 10k's (running races), so I'm running anywhere from 90 to 120 miles per week (13 - 17 miles per day).
- Oh, you're a distance runner, don't you have plenty of energy?? Contrary to popular belief, us runners actually have less energy because we spend it all running!
- So, sure I could just ride a normal bike around, but most of the time I'm just really tired out.
- I love exploring, but there are some places you just can't get with a car, even a 4WD truck.
- I've been living in my tiny house (see instructable here) for 8 months now, and it has a bike rack on the back.
- With this bike, I can now drive my house way out into the moutains, desert, etc, then hop on the bike and explore to those really remote places!
- Nothing like zipping past other people while slowly pedaling backwards.
- The acceleration is REALLY a lot. Like, drop you off the seat if you're not holding on tight.
- Sustainability / Environmental
- As a mechanical engineer, this is a big topic for me.
- Electricity is not necessarily 100% "free" or "clean", but riding around a light electric bike instead of driving a large truck is obviously an improvement in terms of energy use and emissions.
Step 2: Design and Options
Time to build a bike. Where to start? This step will outline the design process and some options I considered before finalizing a design. Then the next steps will go into detail about choosing parts and putting it all together.
What kind of bike?
Before you can convert a bike to an electric bike, you need the bike. The two main choices are mountain bike or road bike. Consider where you will be riding, the size of motor you're interested in, and how much pedaling you want to do. In general, mountain bikes are more stable due to wider wheels and heavier frames. Road bikes also generally don't have a suspension system, which means you'll feel every little bump. This goes from being slightly uncomfortable to painful and/or dangerous as you get up to faster speeds. So, I personally think the safer bet is a mountain bike, and you still have tons of options for getting exactly what you want out of the bike.
Buy, Modify, or Build?
For those on a tight budget, pulling the dusty old mountain bike out of your garage might be the best bet. Craigslist is also a great source for cheap used bikes of decent quality. For new bikes, sites like BikesDirect have some really good deals because they cut out the middle-man retailer. If you find something that's almost what you want, it may make sense to purchase that complete bike and swap out any components you want to upgrade (that's what I did). Finally, if you're feeling ambitious, you can always just collect all of the parts that make up a bike and assemble them all yourself.
Depending on the size and power of your motor, it's important to make sure that your bike of choice can handle the extra stress and weight of your conversion.
One last thing to mention is that building a bike up from parts is not necessarily less expensive. In fact, it's often more expensive. The tradeoff is that you get exactly what you want and don't pay for anything else.
Motor - Hub motor, mid-drive, or chainsaw?
A hub motor is one that replaces either the front or rear wheel hub (the middle part) and occasionally both wheel hubs. They are generally the lowest cost option, most discrete, and lowest powered. They are commonly sold in power ratings of 250 to 1,000 Watts.
Mid-drive motors go - you guessed it - roughly in the middle of the bike. They generally have an extra chain that drives the front crankset, which then drives the rear wheel. One of the coolest advantages of mid-drives is that they let you shift through your rear gears as you could on a normal pedal bike. This gives you a good range of speed and torque for everything from climbing steep dirt hills to cruising along your commute to work.
I've seen mid-drive motors in powers from 750 to 10,000 Watts. There is a practical limit to power here. At some point (I'd like to say it's around 3,000 W), the amount of torque and speed is just too dangerous for a bicycle. Additionally, bicycle components are usually not designed to handle super-human amounts of torque. At the very least, your components will wear faster than normal; at worst, components will break as you ride (think wheel getting bent out of shape, chain snapping, chainring bending, etc). If you really want that much power, I'd suggest a small dirt bike or motorcycle. The motor I got is the "Cyclone 3000" which is rated at 3,000 W. So far that's more than enough speed and torque for me.
Mostly kidding about this one. You certainly can take apart a chainsaw and strap the motor onto your bike to make it go, but it's probably a gas motor (not electric), so it doesn't belong in this Instructable.
Step 3: Bike Tools
First, let’s take a look at tools. The number of tools you will need depends on how much you plan to build a bike up from parts as opposed to buying an off-the-shelf assembled bike. Unfortunately, bike tools are fairly specialized, so in many cases you can’t just “make do” with the tools you have already. Here is what I'd consider the bare minimum toolset for this project:
- Metric allen wrench set
- Adjustable wrench
- Chain breaker
- Bottom bracket tool
- Crank puller
- Socket wrench with metric sockets
If you’re someone like me and bikes aren’t your lifelong passion, I’d suggest getting an inexpensive set of bike tools that covers most of what you need. I got this kit from Luna Cycles for $40. Nothing in it is high quality, but the tools do the job. Compare this to a comparable ~$200 kit from a high quality company like Park Tools, and the value of the cheap kit becomes apparent.
Step 4: Bike Parts
If you’ve decided to buy an off-the-shelf bike and convert it to an e-bike, you can probably skip this step. On the other extreme, you can buy all the parts you need individually and assemble your own bike. There’s also the middle ground of buying a complete bike and upgrading particular components that are important to you.
This last option is most nearly what I did. I bought a decent, like-new mountain bike on Craigslist for $100, then upgraded the fork, brake calipers, brake rotors, wheels, and tires. The complete list of parts and pricing I used can be found here.
If you choose to build your bike up from parts and it’s your first time, it can be a bit intimidating. To help you get started, here’s a complete list of parts needed for a typical mountain bike build:
- Bottom Bracket
- Front Crankset
- Handlebar grips
- Brake levers
- Derauiller levers
- Front Derailleur
- Rear Derailleur
- Brake calipers
- Brake rotors
- Cable housing
- Rear cassette
- Front wheel
- Rear wheel
- Wheel axles
- Tubes (unless tires are tubeless)
- Seat post
So, this is a long and intimidating list. Some things are definitely worth upgrading and getting right (like brake calipers and rotors). On the other hand, I didn't feel the need to spend time and money on many parts, like nice handlebars or a stem. This brings us to the next (optional) step: finding a donor parts bike.
Step 5: (Optional) Parts Bike Teardown
If you bought a mostly or fully complete bike but want to replace some parts, start ripping it apart! Well, use your bike tools and do it carefully. Rather than write an essay here on how to remove every component, I'm going to suggest you learn what you need as you need it. I used Park Tool's Videos on YouTube a lot to learn some basic bike stuff. If that doesn't work, try some google searching. Finally, your local bike shop is always good for advice and, if you're really stuck, you can pay them to just do something for you.
Step 6: Electronic Parts and Tools
I don’t think you need any additional electrical tools/parts for this project, but here are some that I found useful :
- Soldering iron and solder
- Wire strippers
- Heat shrink
- Wire (10 AWG)
- XT90 connectors
- Zip ties
There are a couple essential electronic parts needed for this build. They are:
- Motor controller
You can certainly add complexity with more components, but that's all you really need.
Motor types were discussed a little bit in Step 2. The size and type of motor you get will determine how fast you can go and how quickly you can accelerate. Bigger motors come at the expense of more weight, more power consumption, faster wear on chains/sprockets, and more danger to the rider.
The most common battery chemistry used on E-bikes is Lithium-Ion. I won't go into battery chemistry, so do some googling if you're interested. Most E-bikes use a pack of many 18650 cells wired together to effectively make one big battery. A 18650 cell is just a specific lithium-ion battery that's a little bigger than a household AA battery. You can make your own battery pack, but that would be a whole separate Instructable.
Battery packs are sold with a voltage (in Volts) and capacity (in Amp-hours or Watt-hours) rating. Common battery voltages are 24, 36, 48, 52, 60, and 72 volts. A higher voltage battery generally translates to a faster and stronger response from the motor. More capacity means the battery can store more energy, so it can power the motor for a longer time before needing recharging. Here's an example: I got a 60 V (Volt), 24.5 Ah (Amp-hour) battery. If you multiply those together, you get 1470 Wh (Watt-hours). If I go out for a ride and my motor uses an average of 735 Watts of power while riding, then I can ride for 2 hours before my battery is completed discharged. Higher voltage and bigger capacity batteries are heavier and bigger.
This component is the interface between all of the other components. It controls signals and power to make your motor function as you want it, without damaging anything. Some controllers are programmable, so they have some options you can change. For example, there is an adjustable low-voltage cutoff that will automatically turn off the motor if the battery gets below a certain charge to prevent damage from over-discharging. Controllers are usually rated by the amount of current they can handle. For example, I have a 60 Amp controller. With my 60 volt battery, that means the maximum power the controller can handle is 60 Amps x 60 Volts = 3,600 Watts. This is good for my 3,000 Watt motor because it means that the controller will never be pushed beyond its limits.
The throttle lets you control the motor while riding. The most common types are twist throttles (like on a motorcycle) and thumb throttles (which you press with your thumb). This is largely a matter of preference, although thumb throttles are generally considered safer. More on this in the "Safety" step near the end.
Whew. Thanks for reading all that. On to the fun stuff!
Step 7: Assembly Part 1: Tubeless Tires
This was my first experience with tubeless tires. Tubeless tires are exactly what they sound like: they have a similar outer, tough rubber to standard (tubed) tires, but the exterior tire is actually airtight. Tubeless tires require a sealant that kind of looks like watery vanilla pudding to fill any tiny gaps where air might escape.
Some advantages are:
- The sealant allows the tires to be self-healing: if you ride over a thorn, for example, the sealant will quickly fill up the hole and cure, preventing air from escaping.
- Tubeless tires are immune to “pinch flats”, where the inner tube gets crushed between the rim and tire, making a long gash in it and causing your tire to rapidly go flat.
- Tubeless tires can be run at lower pressures (the ones in this project are rated at 35-55 psi, as opposed to some cyclocross tires I have that run 60-80 psi and road tires that can go up to around 120 psi). The low pressure allows the tire to flatten out more on the road/trail, giving you more traction.
I talked to my local bike shop guys, read about it online and then experienced first-hand: getting them set up for the first time is tough, but then they’re a blast. Here’s the process:
- Wrap the rims with a heavy tape. I used double-adhesive gorilla tape and it’s worked well so far. Make sure to overlap the tape by a few inches, and press the tape down on the edges very well. It will save you a lot of time if you do it carefully the first time.
- Make a small, circular hole in the tape where the valve stem will go.
- Push the tubeless valve stem through the hole and secure it with a rubber o-ring and nut on the inside of the rim.
- Mount one side of the tire inside the rim, making sure to align the tire and rim so that the “direction” arrows go in the same direction.
- Mount about 3/4 of the other side of the tire inside the rim.
- Pour ~100 mL of tire sealant into the opening left in the tire. Turn the wheel so that the sealant flows into a “closed” section.
- Use tire levers to finishing mounting the tire inside the rim.
- Use an air compressor to very quickly inflate the tire. You should hear some “pops” as the tire seats against the rim. You can do this with a floor pump (I tried and failed), but it's infinitely easier with even a small air compressor.
- Spin and flip the wheel around to spread the sealant inside the tire.
- Repeat steps 8-9 as needed until the tire consistently holds air pressure. It may take a couple tries.
- If you absolutely can't get a tire to hold air, it's likely that the tape from step 1 got messed up. Use tire levers to remove the tire completely, pull the old tape off, dry all of the sealant off the wheel, and start over from step 1. Avoiding this is the time saving I mentioned in step 1.
Park Tools has a super helpful video on this process. I highly recommend all of their bike videos. I learned a lot for this project just by watching those.
Step 8: Assembly Part 2: Fork, Stem, and Handlebars
There are a couple different types of fork tubes (the part that goes up through the frame), so make sure you get the one that's compatible with your frame. There are fancy tools for installing forks, but I found a soft rubber mallet, a flat head screwdriver, and some patience were sufficient. This is another one of those steps where I could write a mildly helpful essay of text explaining the installation process, or you could watch a short video and get it immediately.
Here's a decent video from Global Cycling Network to get you started.
Step 9: Assembly Part 3: Wheels to Frame
Once the tires are assembled to the wheels, putting the wheels on is pretty easy! If you don't have a bike stand, just flip the bike upside down so it's sitting on the saddle (seat) and handlebars.
The front wheel (the one without the cassette) goes in between the stanchions (legs) on the fork. Insert a quick-release axle, and you're done! The rear wheel can be installed before or after the chain.
Step 10: Assembly Part 4: Brakes and Derailleurs
I'm not going to reinvent the wheel here (ha!). Here are some guys that do a great job explaining what to do with your brakes and derailleurs. If you do end up getting new brake calipers, I recommend the Avid BB7 calipers that I got. They're high-quality and especially easy to set up because you can adjust them in both directions (on the inside and outside of the rotor).
Step 11: Assembly Part 5: Motor, Cranks, and Chains
This part took a little bit of figuring out, but it isn't that bad. The main challenge is that the Cyclone 3000 motor is a Chinese import, so there's no official video or datasheet that shows you how it goes together.
Here's a simple video showing the first part of the installation from the folks at Luna Cycles.
Here's one showing how to remove or install a crankset from Park Tool. I installed a 3-sprocket 44/44/32 (number of teeth on each ring) crankset, but the short length of the chain from motor to crankset makes it impractical to shift while riding. I leave the drive chain on the 44 tooth ring, which provides less torque but faster top speed. I find this still gives me more than enough torque. Having the geometry of 3 sprockets instead of 2 helps to straighten the path of the chain from motor to crankset, reducing wear and preventing the chain from jumping off while riding.
After the motor and front crankset are mounted, it's time to install the chains. Using a chain breaker tool, get each chain to the right length so that it has just a little bit of slack when in the most stretched position (but not yet tensioned). For the longer chain going back to the rear cassette (on the rear wheel), the rear derailleur keeps the chain properly tensioned. For the shorter chain coming from the motor, there is a small idler gear with a spring that adds tension.
Step 12: Assembly Part 6: Connect Those Wires!
AHHHHHHH! Is the sound I made when I unpacked the 60A programmable motor controller. Wires everywhere. Don't worry, this looks crazy, but it's actually not that bad. Let's go through this a little more systematically.
- Most if not all of the wires coming out of the controller are labeled. Ok, we can do this.
- A lot of the connectors are not going to be used. Manual cruise control, automatic pedal assist, e-brake sensors....these are all non-essential things that you can worry about later (or not).
- Most of the connectors are unique (in other words, fool-proof). You can try to connect things that don't go together, but the connectors won't fit.
Here is a well-written guide on the bare minimum wiring needed to get the bike up and running.
Side note: sorry for the lack of good pictures in this step. See the above "well-written guide" for some nice pictures.
Step 13: Safety
This project is essentially building a high-power, low-weight electric motorcycle. It can definitely be dangerous to the rider and others. Here are some things I did to make it safer:
- Wear a helmet.
- Pretty self explanatory.
- Upgrade to larger (180mm) disc brakes.
- Larger diameter disc brakes means more stopping power, so you can come to a stop faster. This is necessary because of the faster speeds (up to ~50 mph) and heavier weight (~55 lb) of the bike.
- Hydraulic brake calipers offer even better stopping power, but I stuck with mechanical calipers here to reduce cost and complexity.
- Often bike lights are there so other people (and cars) can see you at night. I installed a small, flashing red light on the rear of the bike that lets people see you from behind. On the front, I mounted a large 15 Watt LED headlight that makes it easier to be seen but also illuminates the road/trail in front of the bike.
- These can sense if you’re applying the brakes. If the brakes are on at all, they cut off power to the motor. This prevents the scenario where you’re accidentally applying throttle and brakes at the same time, intend to stop, but the motor keeps propelling you forwards.
- Twist throttles can be dangerous. If the bike starts to get out of control, your first reaction is usually to hold onto the handlebars tight….pulling on the throttle more. This can turn a slight mistake into a serious crash. This doesn’t usually happen with a thumb throttle just because of its location.
- This makes the motor spin up gradually in response to the throttle, making it less “jumpy”. With a large, high-torque motor like the one I installed, it’s very easy for the bike to get out of your control if it accelerates suddenly.
Step 14: Future Mini-Project 1: Battery Box
I originally planned to make a box for the battery and controller as part of the build, but it turned into a more challenging project than I had anticipated. So, for now the battery is in a vinyl bag that came with it and the controller is zip-tied to the bike frame.
Why a box for the battery and controller?
- Prevent theft.
- The battery was the most expensive part at $800. Putting it in a locking metal box would hopefully deter potential thieves.
- It's nicer looking.
- As you saw in some of the previous pictures, that controller has dozens of wires coming out of it, many of them unused. Putting them inside the box with just a port or two makes for a much cleaner looking bike.
- Protect electronics.
- In the case of a drop or crash, the battery and controller will stay protected within the box (with some padding). The box will be bolted to the frame with the "water bottle holder" bolts. This still isn't perfect, but it's much better than the setup I have now.
- Ideally this box will also be watertight, so it will protect the sensitive electronics from moisture.
How are you going to make it?
I started out on the design with some 0.063" thick sheet aluminum I had left over from a different project. As you can see from the pictures, I luckily have access to some sheet metal tools (a large shear and brake) where I work. I made a triangle-ish shape with the edges bent in, then attached separate panels for the sides. This was my first experience with aluminum brazing and I found it frustrating. It was very difficult to stay on the fine line between getting the metal hot enough to melt the brazing rod and getting it too hot to the point that the metal warped. After some failed attempts, I switched over to a combination of rivets and brazing. I think that I will chalk this up as a failed attempt and start over on the box with my learned lessons.
Step 15: Future Mini-Project 2: Cycle Analyst
The Cycle Analyst is an electronic device that allows you to monitor and control all sorts of fun things on an electric bike. I read some great things about it, poked through the manual, and decided to get one. As I finished up the bike and motor assembly (just about a week ago), I was anxious to get riding, so I skipped the Cycle Analyst installation for now. It has been added to my ever-growing projects list =)
Here's the Cycle Analyst 3.0 product page if you want to learn more.
Step 16: Resources
As with most good projects, I couldn't have done it without a bunch of help from the internet. Here are some sites I relied heavily upon:
- Luna Cycles - reputable, U.S. based supplier of electric parts.
- ElectricBike.com - partner site to Luna with lots of great information.
- Amazon - good place to look for parts and get 'em fast!
- Local Bike Shop - I went to a few different local bike shops throughout this project, and the people there were generally very friendly and knowledgeable!
I also created a google spreadsheet to share:
- Comprehensive list of online resources I used
- Final bill of materials for everything used in the build
Well, that's it! Thanks for reading! If you enjoyed this, please consider voting for it in the Instructables Wheels contest. To see some more of my work and learn about starting your own project through my company, check out Thunderstruck Studios.
First Prize in the
Wheels Contest 2017
AviationMetalSmith made it!