You Can Build an Ebike. Yes, You.

Just like regular bikes, electric bikes experienced a pandemic boom, giving more people an alternative way of commuting, picking up the kids, or just getting outside. But you might already have a functioning bike and wonder if you need to invest in (or make room for) another. If you’re willing to put in some light to medium work, you might not have to. How do I know? Let me tell you—I’ve done it myself.

My wife likes to commute by bike to her job in Washington, DC. There’s just one obstacle: Capitol Hill. Not legislation, but the actual, elevated land feature. It’s no Colorado mountain, but it is a challenge, especially when she’s hauling work gear on a swampy day.

I, a bike nerd, leapt at the chance to draft her into the ebike brigade. But my local shop had maxed out its waitlist months before. Even if I could find an ebike, we’re apartment dwellers, and our building’s bike-storage area only has so much room. We would have to choose, it seemed, between her familiar 1990s hybrid or a new purchase.

Or, it turned out, I could just make an ebike.

I could replace a wheel or the bottom bracket of my wife’s bike, run some cables with Velcro and zip ties, and attach a battery. True, the task requires moderate research, light to medium wrenching, and variable fiddling. But if that sounds like a good trade to get some lithium-ion pedal power, let’s go over how to add some DIY range or hill power to your own bike.

Where should the motor go on your bike?

Closeup of a front wheel of a bike with a front hub Ebike motor installed.
Photo: Kevin Purdy

Ebike conversion kits come in three main kinds, which I’ll list from least to most complex in terms of installation:

  • Front hub (shown above): This process entails swapping in a new front wheel with a motor at its center.
  • Rear hub: You make a similar swap, but for your rear wheel (in addition to a new freewheel or cassette cogs).
  • Mid-drive: You install a motor beneath your pedals (in your bike’s bottom bracket).

Each setup has its pros and cons (see the tables below). The more you know about your bike, and how hilly and far your typical ride will be, the easier your choice will be. The hard part is forecasting how much power and range you’ll want once you’re into ebiking, said Adam Ostlund, managing partner at Electrify Bike Co., an ebike seller and shop in Utah. Ostlund gets customers saying that they haven’t ridden in 20 years, and that they only want to take weekend rides with their spouse—but a year later, they’ve hit 3,000 miles and want upgrades. “Once someone starts riding ebikes, they’re always going to want more. So we try to start them at ‘more,’ so they don’t regret it later,” he said.

Front hubs

Pro Con
Easiest install Torque arms—additional metal bracing to secure the axle in the bike’s frame—advised for more than 250 watts, complicating flats and repairs
”All-wheel drive” (when also pedaling) on flat roads Less traction on steep hills and poor road conditions
Lower cost than rear hubs or mid-drives Easier to overheat motor on hills or spin-outs
More battery-placement options (using smaller batteries) Trickier handling and balance for inexperienced bikers
Discreet look thanks to a smaller motor Limited in power (500 watts or less recommended, especially with aluminum or carbon forks)

Rear hubs

Pro Con
Easier install than mid-drives Changing tires becomes more inconvenient
Better weight balance and traction for hills and rain Larger motors make heavier bikes
Higher power ranges available Torque arms needed for higher wattages
Fits bikes with irregular bottom brackets Drivetrain and wheel components may be cheaper quality than original bike parts

Mid-drive

Pro Con
Allows you to use your bike’s gears to shift between torque and speed Faster drivetrain wear
Better weight distribution Less clearance under the bike
More safe power configurations Best to avoid shifting while motor is engaged
Better for mountain/trail/hill riding More intensive install with specialty tools (and sometimes frustrating bottom-bracket sizes)

Most DIY ebike enthusiasts prefer mid-drive motors, which leverage the bike’s gears to alternate torque and speed, unlike the blunt push of motorized hubs. They’re generally safer for your bike’s frame, especially with newer bikes made of aluminum, carbon, or alloys instead of older, tougher steel. They make more efficient use of battery power, especially on hills. And a mid-drive motor’s weight sits evenly in the middle of the frame, rather than at the front or back. If you’re planning to tackle hilly trails, off-road conditions, or long ranges, a mid-drive setup is definitely best.

But hub motors have their place. They start at lower prices than mid-drives. They’re notably easier to install than mid-drives, and they let you avoid dealing with installing a motor into your bottom bracket—a bike part that can be notoriously varied in kind and size. Hub motors are a decent choice for commuting on paved streets with light to medium hills, when you’ll be using your legs most or all of the way. Just make sure that you brace your bike frame properly.

How will you control the motor?

Closeup of a handle bar on a bicycle that has a E-Bike Throttle Control installed.
Photo: Kevin Purdy

Your decision depends on what kind of riding you do. Most kits offer three main ways to control how much power your bike’s motor supplies and when: a throttle, a cadence sensor, or a torque sensor. Some bike kits include both a throttle and a sensor for your choice or combination.

A throttle is what it sounds like: a button, lever, or handlebar twist that lets the rider manually apply power with no need to pedal. Throttle riding is what you see delivery riders using in major cities. It uses a lot more power. It’s also a useful backup if the bike, or the rider, starts to fail during a ride.

A cadence sensor turns your motor on when you are pedaling and off when you stop, increasing its output the faster you pedal. It’s usually paired with a kind of shifter for the rider to choose the level of assist (you’ll see this system on most shared city ebikes). It’s more hands-free than a throttle, but it can be a bit awkward in low-speed situations, such as when you’re starting from an intersection.

A torque sensor gives you more power when you’re pressing harder on the pedals, whether you’re climbing a hill or pushing for speed. Torque sensors feel the most natural—they push hard when you push hard—but require more work to install and maintain.

How much power and battery do you need?

An overhead view of a bicycle with a battery pack strapped onto the back.
On my wife’s bike, a bungee net attaches the battery to the rear rack. At this size, the battery is relatively easy to remove—handy if she needs to leave the bike locked up for a moment. The battery is reasonably water resistant, but not waterproof, in its original packaging, so during heavy rains, my wife covers it with a plastic shopping bag that she keeps in her pack. Photo: Kevin Purdy

Once you’ve chosen a kind of motor, you decide how much motor you want, as well as how much battery you want behind it. Motors have watt ratings, batteries have voltage and amp-hours—it’s a dense thicket for a newcomer. Micah Toll, an engineer who writes at EbikeSchool.com and Electrek, helped me focus on what matters.

First lesson: Ebike motor ratings are mostly nonsense. Some countries cap ebike motors: 250 watts in much of Europe, 750 watts in much of the US. Not coincidentally, motor makers and sellers advertise a motor’s “continuous” power instead of its peak rate. The more clear way to compare ebikes is to look at the voltage and current (amperage) for hill-climbing and top-speed power and to consider watt-hours for battery longevity.

You can tweak the voltage and current with different battery controllers, gaining more speed, more hill power, or different assist levels. The power you need depends on a lot of factors, including your body weight, the bike’s weight, and your pedaling power. Bicycling magazine has a deep dive on how to understand ebike motors and power (presented by Bosch, which makes its own ebike motors). Generally, Toll suggests, 24- and 36-volt setups are for casual riders who plan to pedal a good deal and don’t face lots of hills, while setups at 48 volts and above are useful for hills and no-pedal throttle riding.

I went (very) small for my wife’s roughly $650 ebike kit from a company called Leeds: a 250-watt, front-hub motor, powered by a 24-volt battery with 5.2 amp-hours, roughly the size of a squared-off 16-ounce beverage can. But watt-hours (Wh) offer a better battery comparison than amp-hours (Ah) do. You get watt-hours by multiplying the battery’s voltage (in this case, 24) by its amp-hours (5.2), so for my wife’s kit, that works out to about 125 Wh. Technically that means her fully charged battery can run her 250-watt motor at full power for about half an hour. It’s a useful comparison, but ebikes pull “full power” only during hill climbs and acceleration, so their batteries usually last much longer. On a paved-road commute, your legs can likely put in 100 to 200 watts of power on their own, so using a low-key kit like this is like having an on-demand tandem partner.

For such “assist” rides, 250 Wh is a better starting point these days, according to Toll. If you’re going to be riding your throttle most of the ride, 500 Wh (that is, a 48 V, 10 Ah setup) is your starting point.

If you want something close to an electric moped experience—almost entirely throttle, 25 to 28 miles per hour—you’re looking at a 750 Wh setup. At that point, you should be checking your local laws and also considering whether you ought to simply buy a dedicated ebike, because in terms of price, design, and safety, you’re likely better off with one.

My wife’s ebike is working well. Because she can safely store her bike at work and at home, she removes her battery only about once a week for charging. She gets most of the exercise of biking but can push a button to get a faster start at intersections or to tackle hills. It has made her more confident in biking around the city, which means the local bike shops still get some business in accessories, lights, and more.

Do you need to upgrade your brakes?

If you’re installing a lightweight battery and motor that you expect to use mostly as an assist to active pedaling, your current brakes may be fine. Disc brakes provide better stopping power, especially in wet conditions, but a good rim brake can suffice for commuting-focused rides. Toll said he spent three years riding a DIY 1,000-watt ebike with mechanical V-brakes (the kind you might see on a 10-year-old mountain bike), and it worked out well. “It’s more about the quality of the brake,” he said. At a minimum, though, check your brake pads and performance, or have a shop do a tune-up, when you’re installing a kit.

Many ebike kits and motors come with replacement brake levers, or sensors that can attach to your existing levers. These shut off the motor when pressed so that your motor stops pushing immediately when you mean to stop. I haven’t found them helpful on my own 250-watt setup (more on that in a bit), but there’s no harm in installing them.

Where should you buy a conversion kit?

Side view of a bicycle that we coverted into an Ebike using a conversion kit.
The cables running from the front-hub motor to the throttle button on the handlebar, and then to the battery on the rack, are held in place by zip ties and Velcro. (The cables sagging off the top tube could use some attention.) Photo: Kevin Purdy

There’s no one ebike kit that I—or anyone—can recommend for most riders and bikes. But Adam Ostlund, Micah Toll, and Karl Gesslein, ebike enthusiast and author at ElectricBike.com, all offered one bit of buying advice: Never try to “save money” by hunting for cheaper batteries. A cheap battery is almost always disappointing—and sometimes dangerous.

Bike batteries usually consist of a series of 18650 cells that are connected to one another and a battery-management system and then packaged into various shapes. Reputable battery makers and ebike-kit sellers use the best-quality cells from brand names like LG, Panasonic, and Samsung. In contrast, most discount sellers use lesser cells, from lesser-known makers, that have diminished capacity, voltage, and longevity, and their controllers can be equally suspect. Buy from a dealer with an established presence and return policy.

You can often find motors, batteries, controllers, wires, throttles, sensors, and other accessories sold separately, but unless you have a few conversions under your belt, you’re better off with an all-in-one kit. Kit makers have spent a lot of time testing how components work together, and they should be available for troubleshooting. Ostlund noted in our interview that Electrify Bike custom-programs some of its kit controllers so riders aren’t stuck with the often aggressive acceleration curves of some motors that are meant more for delivery workers than for weekend warriors.

Ebike-kit companies that were mentioned by the experts I talked to, are linked in ebike-enthusiast subreddits, and have generally built a good reputation include:

What about Swytch kits?

Search online for ebike kits (or in the comments posted on this article after its original publication), and you’ll see Swytch mentioned a lot. It’s a UK-based company, but it has a US warehouse for returns and distribution, as well as a one-year warranty on most parts. The company offers 250-watt, front-hub-based full conversion kits for bikes with 26-inch and 700c wheels, as well as for Brompton folding bikes. You have to preorder your customized kit, and you might wait a while, as Swytch prepares and ships kits in batches.

Swytch’s main hook is its unique battery and connector, which clicks on and pops off your front handlebars at the press of a button. Most people have room on their bikes there, and the design simplifies removing the battery when you’re locking up. Swytch recently announced the smartphone-ish–sized Air battery for those who value even more portability, and lighter weight, over range.

Swytch sent me a test kit for my own bike—a 2018 Norco belt-drive hybrid with 700c wheels—with a Pro battery (30-mile range) and both a cadence sensor and a throttle. After jumping on a video call to double-check my fork dropout width measurement (an important detail for any conversion kit), I ran the cables and installed the kit without much hassle.

My bike is already on the heavy side, and I’m biking for errands or recreation more than personal records, so the roughly 3 pounds of difference that Swytch’s motorized front wheel adds is tolerable. You’re more likely to notice the 4-pound battery on the handlebars, but that feeling soon disappeared for me—and so did hills, and starting on an incline, and feeling weighed down by cargo.

There are better ebikes for those committed to riding electric every time or for those interested in commuting longer (or steeper) distances with less pedaling, but I’ve enjoyed the versatility of the Swytch kit for weekend trips and weekday errands. If hauling a battery around will be a pain, or the ride is real short and my knees feel great, I can skip it. If I want a faster, smoother ride, I can grab the battery and head out. If bike space and versatility are a priority for you, the Swytch kit is worth considering.


If you’re unsure about any aspect of your conversion, look for your bike model on the Endless Sphere forum or the r/ebikes subreddit, or simply search the web for your bike name plus “ebike.” Bike owners who have stealthily converted their bikes into electric-powered dynamos love to tell people about it. Not that I’d know anything about that.

This article was edited by Christine Ryan.