Shuangye ebike
E-bike conversion kits are a solution that allow you to add a motor, battery and electric controls to a non-electric bike to make it into an e-bike. Chosen with care and installed correctly, the resulting e-bike lets you ride with electric assist just like a ‘regular’ e-bike. With the range of readymade e-bike designs larger than ever, kits have some competition from off-the-peg, ready to pedal e-bikes. However, they still offer positive advantages as well as some drawbacks which are considered first-off.
E-Bike Conversion Kit Pros
You Like Your Current Bike: You might want a bit of power assistance on a cherished non-electric machine that fits you like a glove.
Unique Bikes: The type of bikes you prefer may not be available in electric versions (folders and recumbents are cases in point, though more are appearing on the market, especially e-folders). Electric bike conversion kits can be useful at the ends of the power envelope less catered for by off the peg e-bikes, that is to say moderately powered but very ‘bikelike’ machines or at the other end of the scale, power hungry beasts.
Swapping: E-bike conversion kits can be swapped between bikes, giving the option of trying electric-assist on several different machines. Similarly, if the kit is a very easy to remove front hub wheel kit (for example as is the case with Leeds, Cytronex,Swytch etc.), you can use your bike unassisted at any time by simply swapping the wheel back to the original and leaving the battery off (the bike then weighs just a few hundred grams more than before). With such systems you can also choose at any time to electrify more than one bike and fully utilize your battery, just by swapping it between bikes.Greener: If you already have a bike you want to make electric, e-bike conversion kits are generally a ‘greener’ option than a brand new e-bike, for the obvious reason they don’t need another brand new bike to be manufactured to replace the one you have bought!
Tinker or Do Something Totally Different: Those who love fiddling with bikes may be intrigued by the endless permutations of motor kits and bikes – the performance of a kit will be affected by the bike it is fitted to. Hub motors are usually geared for a specific wheel size to ensure they stay within the speed limit set for electric bikes in the territory in which they are sold. However, to take one example of how you can play with the design characteristics of motors and bikes, if you fit a hub geared for a larger wheel into a smaller one it will give excellent pulling power at low speeds, producing an excellent hill-climber or load-hauler.
You even have the chance to design an e-bike radically different to anything any mainstream manufacturer offers. To give one example, Canada’s Grin Technologies have a range of solar panels and associated devices that allow for solar charging of your e-bike conversion kits bike as you ride along.
Great Value: E-bike conversion kits can be great value for money. If you have a ‘recipient’ bike languishing in the shed or have picked up a decent quality steed at a good price, it can be converted quite cheaply when compared to the cost of a new e-bike of similar quality. Do note the Fitter’s Responsibilities section below about the quality of the recipient bike you might want to fit a kit to.
Lightweight: Kits also make it possible to put together an incredibly lightweight electric bike – a total weight of 22 pounds or 10kg is actually possible, and if money really is no object even lighter! There are an increasing number of off-the-peg lightweight e-bikes available now however, though these are generally mid to high priced e-bikes, so e-bike conversion kits can still be an economic way to a lightweight e-bike. E-bike conversion kits that add a little over 3kg to the weight of a non electric bike are now widely available and there are even lighter options out there, though these tend to be rather light on the amount of power assist you get.
IMPORTANT NOTE:
Kits containing illegal motors and control units are in the market, and many people are using them on the road, either innocently or otherwise. A fast and/or powerful kit can be a lot of fun, but bear in mind that once you exceed the parameters set in the regulations, you are on your own. In most territories, your bicycle will be treated as a moped in the eyes of the law, and subject to the much more stringent penalties that come with motorcycle use. If you are found responsible for injuring someone, you will be in very serious trouble. The electric bike legislation is a safety net for your protection, and you leave it at your own risk.
E-Bike Conversion Kits: Which Kit is for Me and How do I Fit It?
Geared or direct drive conversion kit system?
The vast majority of e-bike conversion kits are geared, whereby the motor power needs to be geared down via a set of compact gears on its way to the hub shell. They are fixed gear, usually being geared to achieve a maximum speed of 15.5mph or 20mph (depending whether you are buying a European or US spec kit). However, they may be geared to give the maximum amount of hill climbing ability and so the top assisted speed of the motor may (rarely) be less than the actual legal power assist limit.
Direct drive motors do not ‘gear down’ onto the hub shell, so in reality the hub is the motor itself. Whilst this might sound ideally simple, motors generally like to spin a lot faster than the 200-400 rpm bikes wheels typically spin at and the direct drive design also tends to lack the torque of geared motors, so crucial for effective and efficient hill climbing abilities. To compensate for these inherent characteristics direct drive motors are often made with a wider diameter than geared motors to help them gain torque and so any weight saving gained by the lack of gears tends to be lost by their larger size.
That said they have definite advantages that might be important to you such as near silent running (though some geared motors are now extremely quiet) and an ability to brake ‘regeneratively’ using the motor. The latter however, is more a ‘comfort’ feature, allowing you to brake on long sustained descents without having to keep a hand on the brake lever all the time, rather than a feature that puts a meaningful amount of power back into the battery.
Most e-bike conversion kits range from around 7 pounds or 3.2kg for the Cytronex with the Nano system in a similar range all the way up to 20 pounds or 9kg plus for a beefy motor with extra large battery. Very heavy kits could also potentially push the load on the bike (with the rider and luggage) over the recommended limit for that bike. There are some ultra light friction drive kits around though you shouldn’t expect too much from the amount of power such sub 4.5lb / 2kg systems can deliver.
Just as important is the weight distribution of the kit, as too much weight in the wrong areas can affect the handling of the bike. This usually means careful attention to where the battery sits – a heavy battery attached to the handlebars is inadvisable as this can badly affect bike handling and even the common approach of integrating it into the rear rack can noticeably affect handling.
Ideally the battery should be placed as low down and as centrally on the bike as possible, so you should consider if mounting the battery on the downtube of the recipient bike is possible. If that is not possible a bikepacking style frame bag attaching along the top tube is not a bad compromise as long as the battery isn’t too heavy.
This can vary a lot between e-bike conversion kits and from bike to bike but below is a non-comprehensive list of things you should consider. Please check with the company that you are purchasing a kit from for their specific fit requirements.
Read more bike tips:
Can an Obese Person Ride an E-Bike
How to Safely Store an E-Bike: Outside vs Inside
How to Improve Your Cycling Performance
Top 12 Things to Know Before Buying a Cheap E-Bike