THE PERILS OF DIY E-BIKES

The ins and outs and the do’s and don’ts

By Nick Claire

E-bikes are hotter than ever right now. With all the buzz, people seem to be dreaming up any way to get themselves e-ified. When it comes to home-built e-bikes, it could just be worth doing. Although, I suggest doing a bit of analysis of your purpose and what style of riding you’ll mostly be doing.

MY TWO CENTS

When it comes to building your own e-bike, it’s important to consider first how you’re going to use your e-bike. Certain applications could potentially cause equipment failure sooner than expected, leaving you with a project bike that you’ve spent money on that’s just sitting in the garage. On the other hand, I’ve seen people make heavy-duty-quality home builds that can take a beating out in the mountains. With that said, there is extra cost in building anything with integrity that’s ready to get you thousands of miles of life without major headaches along the way. Keep in mind that it’s not particularly about the money you put into a project if it’s getting you the value you’re looking for. In other words, you may spend just as much building your own e-bike as you would a pre-manufactured bike. If it’s getting you something that you can’t find anywhere else, or if it’s just what’s convenient for you, it could very well be worth the money.

On average you’ll be adding about 10–15 pounds to your bike. It’s important to make sure your other parts, like the tires and brakes, are up to date (disc brakes are preferable). Ultimately, it could be a benefit to upgrade brakes or shop for larger rotors if your bike will allow it. I’ve seen some creative builds that even got me thinking of different possibilities, such as former motocross national champ and paraplegic Doug Henry who has built a downhill GT race bike. He uses a throttle and hits really rough courses and is an example of how a build can be done with durability in mind. It’s just a matter of being technical enough and having the cash to do it right, or paying someone else to build it for you, which can be costly. At my shop I would charge on average about $350–$500 for an install depending on how much custom fabrication we would have to do.

BUY THE RIGHT PARTS

To start, find a reputable company such as Luna Cycle that can help you get the correct parts right off the bat. Make sure the company will be willing to help you work out any issues you might run into during the process. Keep in mind that not every bike is the same. It’s common to miss a step in evaluating what you have to know what parts you need. In addition to the kit and battery, you should also think about buying an e-bike-rated chain. If you plan to put a new chain on worn-out gears, I think it would be better to wait and replace all the drivetrain parts together, because otherwise the chain will skip over the teeth and not cooperate with you. Getting a front chainring with the proper offset is critical as well. Batteries can generally cost between $450–$1100, and it’s a similar price range for motors with the exception of some really high-dollar motors used for custom-built bikes.

This bracket from California Ebike is about $30 and is a quality upgrade that will give much more stability to the motor.

I found one mid-drive kit from Cycle Charged that includes everything you need, including a battery, motor, basic display, wire harness, throttle, cranks, all the sensors and all the hardware you’ll need, as well as a special tool for tightening the motor to the bottom bracket. That kit was $1000 for the mostly entry-level components that would work just to get you going. The main take-away here is that you can spend a lot of time going down a variety of rabbit holes, so beware of how much time and money you want to spend. 

California Ebike is a company that makes a quality brace that attaches to the chainstay and secures a bolt-on mid-drive. It helps secure any side-to-side or front-to-back force coming from the torque of the motor. And, it’s strong and simple to install. Oftentimes the downtube can leave you minimal real estate to attach the mount that the battery slides into. Usually, that mount is flat on the side that sits on the downtube, which isn’t ideal for securing it to the frame. Most batteries are bulky and hefty, which require as much security as possible. There is a Canadian company called Grin Technologies that makes a special mount for the battery that is curved on the side that connects to the downtube. It offers a substantial amount of support compared to just strapping on the mount that comes with the battery.

DOES YOUR BIKE QUALIFY FOR A MOTOR?

Most rear-hub-driven motors can be installed on a bike with the dropout-style axles because the motor has the axle built into it. Checking the width of the wheel spacing and confirming that the hub-drive motor you’re buying matches that width is crucial. Make sure that your bike has a good spot to mount the battery securely. Most hardtails have a decent amount of space in the front triangle to mount a battery. Most bikes with rear suspension lose room to accommodate the linkage and shock.

Many companies will offer the ability to go in to dial your power modes in the way you like and a convenient switch like this will make it easy to change modes.

For mid-drive units, 68mm is the minimum bottom-bracket-width standard. So, again, make sure you have a bottom-bracket width that matches the mid-drive unit you’re purchasing. Some people may even consider a front hub-drive motor. In that case, it’s even more crucial to analyze the strength and quality of your bike. The amount of force on the head tube from the motor pulling the forks forward is more than you might think. This can work for a while, but over time can cause unwanted stress on the head tube and would be disastrous if it failed while riding.

BEING TECHNICALLY INCLINED AND THOROUGH

There are many different companies selling motors and build kits at this point. Although installation may seem like a few simple steps, there can be challenges. Whether it’s mounting a mid-drive unit or a battery, it can take some critical analysis and cleverness to really get everything secured; things like extra bands around the battery to keep it from wobbling around. I’ve seen many batteries jump out of their holders because they were not secured properly. In some cases, you’ll have to cut your wire harnesses down to a more practical length, and it will require soldering them back together. Typically, the battery would mount using the bosses for the water-bottle cage. Find a way to add extra straps or bands around the battery and the controller until you’re certain it’s secure.

Grin Technologies out of Canada makes this special battery carrier mount that helps give the battery more support from side-to-side wobble.

WHAT’S RIGHT FOR YOU?

Note that when you buy a pre-manufactured e-bike, it will have a more natural-feeling power compared to an add-on kit motor. Pre-built bikes will be much more intuitive, integrated and efficient compared to a DIY bike. Other than cost, a good question remains: why do you want to build your own e-bike? Is it because there’s something a pre-made e-bike can’t give you, such as a throttle? Is it a budget issue? In that case, you may be able to get rolling for relatively cheaper than spending big bucks on a pre-made e-bike. Maybe you’re just in the pursuit of doing things yourself, and from my experience, that’s a rewarding feeling and worth pursuing, as long as you’re confident that it can be both cost-effective and safe. Good luck to everyone considering building their own and, like always, send us your letters and pictures with your DIY experiences!

CONTACTS

Grin Technologies: www.ebikes.ca

Cycle Charged: www.cyclecharged.com

Luna Cycle: www.lunacycle.com

California Ebike:
www.california-ebike

edit