Currie Electric Bicycles
Currie Technologies, founded in 1997, offers two lines of electric bikes and scooters known as the eZip and IZIP which offer low and mid-range value. Primary differences include battery type, weight and component grade with IZIP being the more premium line.
There have been subtle changes in the eZip and IZIP lines over the years but the primary trade off has always evolved around the batteries being used and weight of the bike frames.
The eZip line uses Lead acid batteries that are much heavier than Lithium ion equivelents. These batteries can only endure a a small fraction of the charge cycles that Lithium ion can before they begin to degrade and under perform. The up side here is that Lead acid is more stable, easier to recycle and much less expensive to replace. For this reason, the eZip line is built with batteries hanging from a rear saddle rack and can accommodate two batteries instead of just one. The motors on eZip bicycles are also stronger because they have to carry more weight but this also means more wear on the bike and possible handling and stopping disadvantages.
The eZip line of bikes features steel frames instead of aluminum which adds significantly to their weight but dampens some of the vibration felt when riding. Steel is a time tested material in bicycles and is even preferred by some riders today despite advances in aluminum and carbon fiber. Steel is tough and provides a fluid ride but the weight will always be a factor and creates more work for the motor and user when being maneuvered. I’ve lifted both the eZip and IZIP bicycles, one right after another, and the eZip is just so much heavier. When riding it isn’t noticed so much but trying to get it up stairs, into cars or positioned on bike racks can be a real pain.
Traditionally eZip bikes have used externally mounted brushed motors while IZIP’s feature hub motors. The trade offs here revolve around noise, maintenance and weight positioning. eZip motors are mounted on the left side of the bike frame and can create an imbalance in the bike, though I have never felt unstable on them. They also use a chain drive which means more moving parts are exposed to the elements and increase the likelihood of rust and breakage. Hub motors by comparison are mounted right at the center of a wheel and incorporate the spokes and rims right into their design. This is a more balanced approach and eliminates some of the exposure issues with external motors but the downside is that if any spokes or parts of the rim are damaged it is much more work to repair. Imagine swapping one generic bicycle wheel out vs. having to rebuild a wheel by hand with a new spoke or entire rim! This doesn’t happen to often but it is a downside worth mentioning.
The more subtle differences between the two bikes evolve around the brake setup, gearing, suspension and wheels. eZip’s use traditional style v-brakes with rubber brake pads. These provide ample stopping power but wear out more quickly and are susceptible to performance issues if the rim gets wet or dirty in which case they can actually scrape the rim. Chain rings, shifters, derailleurs and gears are all upgraded on the IZIP line and can be expected to work better and last longer than their eZip equivalents.