SCHWEINFURT, Germany – There’s something very special appearing on the horizon of the e-bike market. It’s SRAM’s drive system for electric bicycles. The SRAM E2 Electric-Assist System is launched today at the start of the Taichung Bike Week in Taiwan. It’s unlike anything available yet and is developed around two main focus points: simplicity and drive-ability.
SRAM disclosed the most interesting features of its e-bike drive system to OEM’s earlier this year at Eurobike. At Taichung Bike Week which is being held this week, the complete system has been introduced to numerous product managers for their MY 2013 line-ups.
“No me-too product,” was according to SRAM CEO Stan Day the first established focus point when the e-bike project started. “Other than that we said that we wanted to be right from the start the best in class. And with our background in internal as well as external drive systems for bicycles I am convinced that we can be just that. With that in mind we studied the market and studied in particular on the question what OEMs are looking for with regards to e-bike components and what consumers want.”
These focus points have been turned by SRAM into an ‘integrated’ e-bike drive system that consists of a very limited number of parts. As simplicity safes big on assembly-time, the component maker set out to limit the number of parts of its system and all the goes with it when taking into account that the battery, motor, controller, display all have to communicate through wiring with each other.
With regard to the other focus point - drive-ability - the SRAM drive system functions automatically and with that does what the component maker set out to do; making a system suitable for people used to cars and other modern products that present a sophisticated human interface.
For that SRAM incorporates an rear wheel e-bike hub motor which is special, very special indeed. That’s because it integrates the motor, an automatically shifting 2-speed gear system; a torque sensor as well as the motor controller. The built-in torque sensor measures chain movement as well as frame-flex and is a patented system.
The automatically shifting 2-speed gear system is not SRAM’s new Automatix hub. The e-bike hub shifts automatically between two motor speeds but it uses a different gear system. Also, the shift point is adjustable on the Automatix hub, but it is not adjustable on the e-bike hub. Furthermore, the e-bike hub is built on a single-speed drivetrain (1 chainring, 1 cog) and even though the torque output shifts, the effective gear ratio is always the same, and it is whatever gear ratio that the bike is set up with (42 – 17, 44 – 17, etc.).
These focus points have been turned by SRAM into an e-bike drive system that consists of only 2 parts and one cable. There’s the motor, the battery and the cable that connects the two. An easy to install system to be used in standard IHG frames.
SRAM emphasizes that its e-bike drive system doesn’t need special requirements; there’s only the wiring that goes from the rear wheel hub motor to the battery. And that battery has an on/off button with which the whole system is operated. No handlebar display and cable that needs to be fitted for it.