SRAM Patent Shows Compact Motor x Battery Unit

A recent patent from SRAM depicts an all-new e-bike motor design that is quite the departure from the Brose-powered system that debuted last fall. The patent itself centers on the positioning and arrangement of battery cells, which seem to be located within the motor casing itself, or at least very closely sidled up against it. Placing weight so low on the bike would be advantageous, certainly for a full suspension mountain bike, where handling is massively affected not just by overall weight, but by where the mass is located.



Notable is the method of charging; the patent reads, "Charge current may come from a DC source, or the charge current may be supplied from any USB C power source. This allows consumers to have a single standardized charger for their phone, laptop, and electrically powered bicycle". It's also clear that the battery is to be removable, and can also be used to charge other devices like a phone.

While useful, charging via USB-C isn't all that exciting. However, what's of greater interest is the arrangement of the motor unit itself. It's super compact, with all of the hardware sitting concentric to the bottom bracket.


Most eMTB drive units take on an oval shape, having much of the hardware necessary for the reduction ratio (converting pedaling cadence to the electric motor's rpm) sitting offset to the stator. The SRAM Powertrain, powered by Brose, is one such example. It is a full-powered drive unit with a maximum torque of 90 Nm and a peak power output of 680 W, and it is the engine room of bikes like the Nukeproof Megawatt, Transition Repeater, Gas Gas ECC and the Propain Ekano 2 CF.


There are some mid-powered e-bike motors that are the exception to that rule. Namely, the TQ HPR-50 and the Free Flow Technology FF60. Both run on a similar Harmonic Pin Ring, or Strain Wave technology, that allows the stator to sit inside and concentric to the hardware carrying out that all-important reduction step between the rider's cadence and the motor's rpm. What we see in this recent patent from SRAM is a not dissimilar layout.


Though we can't see inside, it's clear that the drive unit itself is cylindrical in shape, and far more compact than the full-powered Powertrain. While SRAM has leaned upon the Brose technology for its first foray into the world of eBike motors, it'd be naive to assume they weren't tinkering away on a design of their very own. This could be our first glance at that system.

Though there's little to be gleaned at this stage, I'd hazard a guess that we may see a new motor from SRAM in the next few years that takes on this more compact shape, that is lighter than the 90 Nm Powertrain, but also much less powerful - likely in the region of 50-60 Nm.

We did reach out to SRAM for comment, but they decline to comment on patent applications.

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Reviews and Tech eMTB Patent Pending SRAM