Make Your Own EBike: Electric Conversion Kit

by Electric bike guru on May 17, 2010

Would you like to own an eBike?  Have you got an old bike sitting around that you don’t ride very often?  Are you interested in saving some money?  If you answered “Yes” to these three questions, then you are a good candidate for an ebike conversion kit.

You may have seen one of these kits in a camping supply store or an online auction site.  The idea is simple:  the conversion kit supplies all the components necessary to equip an existing bike with electric drive.  Some kits are made in the U.S. and Canada, while many are imported from China, a bike-friendly nation on a budget where electric bikes are all the rage.

Electric conversion kit being installed

Electric conversion kit installation

The typical conversion kit contains a front or rear wheel with a hub motor, an electronic package known as the control module, a twist-throttle or thumb throttle, and a luggage rack and/or a carrying case for the battery.  Many kits include replacement brake handles with disconnect switches which automatically switch off the electric motor when you apply the brakes.  Some kits include the battery, some home-build kits do not.  Often the battery is the most expensive item, costing as much as all the other components in the kit combined.

Quality of conversion kits can vary quite a bit, as can the readability of the instructions.  Replacing a front or real wheel and swapping out brake levers is something that many do-it-yourself folks can manage to do.  If you’ve been riding for a few years and perform most of your own maintenance and repairs, you might want to consider tackling the job yourself.  If, on the other hand, your mechanical experience has been limited to fixing flats, then installing a conversion kit may be a level of mechanical work that is a bit over your head.  In this case, it might be a good idea to contact your local bike shop before you begin to help you prepare for the job, or to set up a back-up plan in case things don’t go as expected.

The electric conversion will increase the speed of your bike at the same time that the motor and batteries will add extra weight.  For this reason, that old ten-speed that’s been sitting in the basement may not be the best choice for a electric bike conversion.  Instead, consider a basic fixed-frame mountain bike or any regular comfort bicycle.  The sturdy frame and beefy tires are well-suited to the task.  And the upright seating position and straight handlebars will give you better control over the bike than the dropped handlebars (“goose-necks”) found on most road bikes.
The main factors which will determine the speed and range of the completed machine are the size of the motor and the power of the batteries you choose.  Motors can range in power output from 250 watts to 600 watts, which is just under one horsepower (1 hp = 760 watts).  The more powerful the motor, the shorter the maximum range of the bike is likely to be. More powerful electric bike kits also make your bike handle poorly since they add too much weight.  If this is your first eBike conversion, your best bet is to choose a motor in the middle of the range, say around 350 watts like the popular BionX PL 350.

When it comes to choosing a battery, .the options are Sealed Lead Acid (SLA), or Lithium Ion.  Sealed Lead Acid batteries are the less expensive choice, while Lithium Ion batteries provide more power and range, but at a higher cost.  Because you are utilizing an existing bicycle you already own and “diy-ing” it (that is, doing it yourself), you’ll might be saving money compared with buying a new electric bike off the showroom floor. (although the finest, most popular electric conversion kit, the BionX conversion kit costs as much as a ready made ebike).  Since that’s the case, it makes sense to pay a little more for Lithium Ion batteries to obtain the superior performance that they provide.  This will insure that the work you put into your electric conversion results in a finished product with the same strong performance and extended range of a store-bought bike costing hundreds or even thousands of dollars more.

Once you have decided which kit and batteries to buy, prepare a sufficiently large space to work that is well-lit and uncluttered.  Put tarpaulins or drop cloths over any surfaces or furniture that you need to protect, and lay out the components to be installed on a clean, flat surface.  Make sure you have the tools you need before you begin.  Now is the time to determine whether any drilling will be required, and if so, make sure you have a corded drill with an outlet nearby or that your cordless drill is charged up and you have the correctly-sized drill bits for the holes that you’ll need to drill.  It can be very frustrating to have to stop in the middle of the job because you have to run to the hardware store for a tool or a fastener, especially if it’s 9:00 at night and the hardware store won’t open for another 12 hours!

Once you have successfully completed your first electric bike conversion, the sky is the limit.  Maybe for our next project, we’ll convert the family car from a thirsty beast with a taste for imported petroleum to a trusty steed sipping clean electric power!

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