I found that there were two general types of eBike builds:
These kits use a motor to drive the chain or belt, that can be run through the bikes transmission.
- Should have a better weight distribution
- Makes use of the bicycle transmission
- Improved hill climbing
- More complicated to install
- May impact ground clearance
- May require a custom frame to fit or optimize
The hub motor may be difficult to grasp at first, until you see one in person. Essentially, the hub of the wheel (usually rear but could be in the front) is an electric motor. Once it is bolted into the dropouts, the motor rotating causes the wheel to rotate and therefore drive the bike. This does not make use of the bike transmission, but it also works even if the transmission is damaged or missing. Ask me how I know this!
- Easier to install
- More compatibility with existing Frames
- Mechanically simpler
- Fault tolerant, you may be able to get home even when you snap the chain
- No impact to ground clearance
- Weight distribution is biased
- Heavy unsprung weight
- Does not get the mechanical efficiency or advantage from the transmission
Hub motors are broken down into two main types:
Direct Drive (DD)
- Mechanically simpler, no moving parts!
- Usually higher voltage and amperage limits, a lot of this is due to heat shedding capabilities
- Less torque ceteribus paribus to a geared hub motor, but this can be offset by feeding it lots of watt
- Heavier in the high power applications
- Very quiet, practically silent
Geared Hub Motor
- More complex
- More torque because of the gear factor
- Quiet, but make a little bit of noise from the gears
In addition to the eBike specific technology, I had to get up-to-speed on how much the Mountain Bike technology had evolved since the late 1990s. A lot had changed!! For example, I had cantilever brakes on my mountain bike. Since then, v-brakes were an improvement, but now disk brakes were much better and common even on low-end bikes. The 2 inches of front-suspension travel I had in my Manitou 2 fork was cutting edge at the time. Now it was common to have 4 inches of travel upto 8+inches! Full suspension bikes that had a lot of drawbacks back in the day had addressed many of the downsides and were more common. I knew that I would want to move to a full suspension platform to make the most of my eBikes. Check out this article for more info.
Terms and abbreviations related to eBikes that make non-enthusiast eyes glaze over whenever I explain them…
Geared Hub Motor
Geared hub motor.
Pros: improved torque for a given power level
Cons: Not as robust and prone to failure, such as by breaking the gears
Watts = Amps x Volts
For example, fully charged 72 volt battery