Many excellent bike shops already sell e-commuters, with more retailers adding them their inventory every month. So then why would anyone want to assemble a do-it-yourself (DIY) e-bike when there are scores of superb OEM models available? The reasons, many and varied, include the cost savings, the assurance that the conversion of a bike that already fits you perfectly will continue to do so as an e-bike, a new hobby, the feeling of accomplishment and an intimate knowledge of the functional parameters of your bike. We take a look at some of the conversion kits that make this swap easy-peasy.

Where Will You Be Riding?

Selecting the style of e-commuter that you wish to build should be based on the same criteria used for purchasing an OEM model, as discussed in BICYCLIST Issue #132. The primary decision is whether you want a California Class 1 or 2 e-bike, which are limited to 20mph bikes that can be ridden on bike trails unless expressly prohibited, or a Class 3, 28mph, pedal-assist (PAS) model that can be ridden exclusively on bike lanes that are contiguous with a road. Other key questions concern the type of conversion: hub motor or mid-drive. Front hub motor conversions are usually the easiest to construct and the lightest. They are excellent for cargo bikes and have nice weight distribution. Additionally, they allow for the retention of your rear gear system, especially if it’s an IGH (internal geared hub) or belt drive.

A bike equipped with an after market electric hub motor conversion kit, with the battery pack placed on the rear carrier rack.
A bike equipped with an aftermarket electric hub motor conversion kit, with the battery pack placed on the rear carrier rack.

The primary liability of front hubs is that the motors are geared and don’t dissipate heat as well as other systems. Rear hubs are generally more powerful and, if direct drive (DD), have only one moving part, making them quiet and effective at dissipating heat. Since they are normally heavier than geared motors, they won’t accelerate as rapidly. Mid-drive systems are very effective for hilly areas and at slow speeds because they multiply the output of the gearing system. But they are more difficult to incorporate into your bike than hub motors, and require knowledge about bottom brackets (BB); also, you’ll need BB tools to install them.

Regulations for eBikes

California law requires that OEM manufacturers include information on 2017 models indicating whether a bike is Class 1, 2 or 3. However, there are not yet guidelines for DIY conversions. We do know that all motors for OEM bikes must be 750 watts (W) or less, so that would be your initial goal. Keep in mind, also, that the desired speed of the e-bike is important.

The Dillenger US front hub conversion kit.
The Dillenger US front hub conversion kit.
The YESCOM 36v 500w wiring, battery and controller unit.
The YESCOM 36v 500w wiring, battery and controller unit.
The YESCOM 36v 500w rear-hub electric motor conversion kit.
The YESCOM 36v 500w rear-hub electric motor conversion kit.

Once you’ve decided on the type of conversion for your bike, you’ll need to find a vendor. If you decide on a rear hub, YESCOM has very inexpensive kits, which include all the components except a battery. If you select a 500w kit, you should be able to meet the California Class 1 & 2 requirements with a 36 volt (V) battery. Should you decide on a front hub, Dillenger US, an Australian company with distribution from Ontario, CA, will save you shipping charges; they are an excellent source and offer a one-year warranty on their kits. The 36V, 13 A/h unit is a winner.

Luna Cycle in Los Angeles is the go-to place for mid-drives and batteries. Their 750w BBS02 is excellent and, with a 48V battery and no throttle, it should be able to meet Class 3 requirements. All of these systems can be purchased for under $1000.

Now that you have the DIY fever, it’s time to begin planning where you’ll ride!