Convert Any Bike Into a Battery-Powered E-Bike

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E-bikes, or electric-assist bikes, have become increasingly popular for getting around town, doing errands, and commuting to work. Though you typically still have to pedal an e-bike, the motor means it’s significantly easier than riding a traditional bike, whether you have a long commute or live in a hill-strewn area or need to haul heavy loads on cargo bikes.

Many manufacturers offer complete bikes, such as Specialized’s Turbo, but if you’re looking for a less expensive option, you might want to consider an e-bike conversion kit, which allows you to convert just about any bike. Maybe you have a road bike that fits you well or a mountain bike that you love — a kit will allow you to add an electric motor to your existing bike.

How They Work
There’s a range of tech available in conversion kits. There are tiny, nearly soundless motors that’ll fit inside a wheel hub or bottom bracket. Last year, Belgian cyclocross racer Femke Van den Driessche was caught with a Vivax Assist motor in her race bike. The nearly invisible motor was detected when cycling authorities X-rayed her bike. There are also larger, more powerful options that are more visible, but also offer greater range and more powerful acceleration.

Most conversion kits include a controller, a motorized hub, and a battery pack. You can add a motor to either the front or rear wheel of the bike. But there are trade-offs for both: A front-mounted motor will make your front wheel heavier and may make the bike harder to steer. While a rear-mounted motor may give you better traction, you’ll need to make sure it's compatible with your gearing and derailleurs.

How to Find the Right Kit
Before choosing a conversion kit, you’ll want to consider your riding habits. If you’re planning short trips on mostly flat terrain, a small, light motor might work well. For longer rides or to climb more hills, you’ll need a stronger motor and extended battery life.

For larger battery systems, you may need a rack or bag to attach it to your bike, and you’ll want to think about how the battery weight will influence your bike’s handling. You might mount your battery pack to a rear rack. A frame bag such as the Salsa Warbird that fits in the front triangle of your bike offers an alternative to a rack and will help keep your load centered.

E-bike kits are sold based on the maximum wattage the motor can produce and the number of amps the controller can draw. Higher wattage will typically give you more speed and increased power for climbing. A controller with a high amp rating, meanwhile, increases acceleration.

In some cases, motors may overheat if run too long at their maximum levels. While a short acceleration is unlikely to cause damage, an uphill slog at maximum power could cause overheating. You might consider a product such as the Cycle Analyst to monitor your bike’s performance. Or look for a kit with a controller that has this information built-in.

Conversion Kit Options
There are numerous conversion kit options available. Here are a few examples, from a basic kit to some more advanced options.

1. If you’re looking to convert an older mountain bike or beach cruiser–style bike, a basic system such as the YescomUSA 500-watt front-wheel conversion will get the job done. Because the motor is located in the front wheel, you don’t have to worry about compatibility with your shifting. The 26-inch wheel size will work for a cruiser or older mountain bike. If you have a newer mountain bike, your wheel size is likely 27.5 or 29 inches, so be sure to check the numbers stamped on the side of your tires. The YescomUSA kit includes a controller, motorized front wheel, and tire. You will need to buy a battery separately, because this kit does not include a battery or charger. Price: $869.99 On special: $169.90

2. LEED Ebike Conversion Systems offers conversion kits for a variety of bicycle types and wheel sizes. Choose your kit based on how many miles you’d like to be able ride between battery charges. The order process helpfully guides you through a series of questions to ensure your conversion kit will fit your bike. They’ll also send you a tire and tube if you need them. LEED can do rear-wheel conversions, too, for a $50 charge. The LEED kits include the controller, a built-up wheel with motorized hub, and a battery with a charger. Hardware for mounting the kit and assorted cables and housings are also included. Prices start at $549 for a 10-mile range kit. 

3. Do you have a cargo bike like the Surly Big Dummy? Or maybe you ride a recumbent and are looking to convert it to an e-bike. E-bike Kit offers a selection of conversion kits for just about any bicycle you can imagine. Its wheelsets are hand-built and it recommends rear-wheel conversions in most cases. For each kit, you can select your wheel size and battery pack. E-bike Kit also offers conversion kits without a battery pack if you want to shop for your own power source. The E-bike Kit controller features a programmable dashboard. All cables and connectors are included. Prices start at $698 without battery, $1,116 with battery for 10-44 mile range. 

And Don't Forget About the Law
The rapid growth of e-bikes has led to some confusion for lawmakers. Are they bicycles or motor vehicles? Federal law in the U.S. allows e-bikes that hit speeds up to 20 mph and produce 750 watts to follow the same laws as bicycles. The maximum speed you ride will determine where you can ride it and what laws apply to you. In recent years, some states such as California and Colorado have passed more detailed regulations, so you’ll want to check your local motor vehicle code. Electric Bike Review has a good run-down of the current state of e-bike law.