It’s big news that mid-drives have really made a splash on the E-bike world in 2013, and the places where they have proven to be most useful is in power-limited countries, where the added complexity of giving the motor the use of the Bikes gears helps make the most of what little power any given E-bike is allowed to have.
In 1998, Mitsubishi filed a patent for a mid-drive that mounts a motor concentrically with the Bottom-Bracket (BB, the pedal axle). Since then, there have been several companies that produced a variation of this theme, among them is Bofeili and Optibike.
Last year I noticed a wholesale distributor for E-bikes with a similar drive in Canada, called eProdigy Bikes (formerly known as EPIK Bikes). The particular drive that they have spec’d is listed as a 36V / 350W drive. I found it odd that they are not rated for 500W, since that is the legal power limit in Canada. The good news is that they use a system that is designed to work with 36V, instead of 24V. To call it a 350W drive suggests that the factory controller is limited to 10A, and a 500W limit (using 36V) would be 14A.
In response to a posted comment below, I’d like to state that this drive system does freewheel, so you can run the motor without pedaling in “throttle mode”, we apologize for any confusion.
A mid-drive using the bottom-bracket allows the motor to use the bikes gears. If you live in a country with a power limit, this allows the E-bike to get the best possible performance from the motor. This is especially helpful on a hilly commute, and it also places the weight of the motor in the best possible location.
This motor appears to have enough copper mass to manage 500W, and I would not hesitate to try that (after adding a temp sensor and read-out), perhaps by swapping-in an third-party controller (like an adjustable Lyen 6-FET?). eProdigy currently only has two dealers in the USA (in California), but they have 27 retailers listed in Canada. The motor is a brushless DC outrunner, with a geared planetary reduction.
The aluminum core of the stator is solidly mounted to the aluminum disc that functions as the planet-gear holder. The edge of that disc is then connected to the aluminum housing, so…it has a much better heat-sinking mass and heat-flow path for heat-shedding, compared to the common geared hub-motors (MAC, BPM, eZee, BMC). By shifting the gears of the bike to keep this motor up in it happy-RPM range, you shouldn’t make too much heat in the first place, but even then…my experience suggests that this motor can easily handle 500W.
Here’s the break-down of the drive system from their web-site.
If eProdigy ever requests a batch of their motors to be made by their supplier with a different Kv (so it can be run at 48V while resulting in the same RPM’s)…I would not be surprised if this drive system could easily put out 750W, which is the legal street power limit in the USA.
Here is a pic of the Bofeili, which is very similar to the eProdigy motor.
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eProdigy currently carries four models to choose from. The Logan, Whistler, Banff, and Cypress. It appears the owners of eProdigy might be snow-skiing fans from Canada, because the names of their E-bike models are also Canadian ski resorts. First is Mt. Logan, in the Yukon. Whistler, in Vancouver. Banff, in Alberta. And finally Cypress, in British Columbia.
The only battery option right now is a “bottle mount” 8.8-Ah Lithium pack, supplied by their partner Dr Battery.
The Logan uses 700C tires, dual disc brakes, Suntour suspension fork, and a 42T chainring driving a Shimano 8-speed 11T-32T cassette (this pic shows the optional NuVinci IGH)
The Whistler is outfitted the same as the Logan above, with the exception of the tires are 26-inch, and it does not include fenders.
The Banff is eProdigy’s step-through frame. It uses a Shimano Alivio shifter with a 3-speed IGH with V-brakes front and rear. It includes fenders with a sturdy two-leg stand. The wicker basket and tan seat with grips are a very stylish touch.
The Cypress is their most affordable model. Although the 350W rear geared hub does not have the use of the bikes gearing for hills, it should still prove to be adequate for many E-bikers who have relatively flat terrain on their commute. This configuration allows for a front derailleur, so this model has 21-speeds.
Here is their home web-page.
Here is their Facebook page.
To contact them, use their new email: info@eProdigyBikes.com
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I was just informed by Melody at eProdigy that they will be debuting an upgraded 450W motor for all of their E-bike models at the Vancouver Bike Show, March 8-9, 2014. Also, they will have an upgraded battery that provides the higher amps needed by the new motor.
Plus, they will be adding another model to their line-up after the March bicycle show. It’s the “Jasper” (which is also a Canadian snow-ski destination), a step-through hybrid with 700C tires, front suspension, and a front disc brake.
The new “Jasper” model.
Written by Ron/Spinningmagnets, January 2014
