BMW’s Latest Electric Bike Patent Has a New Twist

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BMW has filed a new patent showing a longitudinally mounted electric motor within the chassis, as on the Vision DC concept. (BMW Motorrad/)

Electric motorcycles might still be a rare sight on roadways but already we’re starting to see a “standard layout” across the majority of the models coming on the market. BMW, however—which is bracing itself for an onslaught of electric bikes in the near future—is heading out in a direction of its own.

In a typical layout for electric bikes, the motor is normally sited transversely across the chassis, just ahead of the swingarm pivot. From here it drives through a reduction gearbox—normally single-speed—and then a final drive belt to the rear wheel. Belts tend to be preferred over chains because they’re quiet, and with no exhaust to drown it out, chain rattle would become the dominant sound on a chain-drive electric bike.

BMW is following a more typical design approach for its new-generation electric scooters like the forthcoming CE 04, and another for the larger models. (BMW Motorrad/)

BMW’s next electric model, the CE 04 scooter that’s due to be launched in the next couple of months, follows exactly that template, as do Zero’s bikes and the Harley LiveWire, as well as dozens of other machines. But when it comes to the new generation of large electric motorcycles that are planned for BMW’s lineup, the firm is taking a different route.

We know BMW is taking a two-pronged approach to electrics, and for its bigger electric bike models, BMW has secured a range of trademarks using the “DC” name, followed by numbers from 01 to 09. The firm has previewed some of the ideas for that range with its Vision DC concept and the E-Power Roadster prototype. Both those machines share one key difference to the electric bike norm, and it’s explained clearly in a new patent filing.

The new patents show a longitudinally mounted motor with an intermediate shaft offers more flexibility as well as a more compact design. (BMW Motorrad/)

The trick is that the electric motor is mounted longitudinally, following the pattern set by the firm’s traditional shaft-drive boxer twins, where the crankshaft is in line with the chassis rather than running across it. While the design seen on the Vision DC and E-Power Roadster might have been written off as simply a nod to the firm’s gas-powered heritage, the new patent reveals genuine advantages to the setup and introduces a new twist that hasn’t been seen before.

The drawings also show a planetary gearset (labeled “20”) behind the motor to reduce the output shaft speed. (BMW Motorrad/)

The idea is to add a new level of flexibility in terms of motor placement, as well as creating a bike that’s more compact than would be possible with a transverse motor. By using an intermediate shaft—with CV joints at each end—between the motor and the front of the shaft final drive, there’s flexibility in where the motor can be positioned in the chassis. It can be moved forward or back, up, down, or side to side. That’s hard to achieve with the transverse motor approach used by others and means there’s more freedom in terms of styling, weight distribution, and battery placement.

It’s possible that the new reduction gearbox design will make its way onto a production version of the Vision DC. (BMW Motorrad/)

Where BMW gets even smarter is in the reduction gearbox. Electric motors tend to spin fast, so you need to gear them down before transferring power to the bike’s rear wheel. On most transverse-motored designs that means a secondary gear shaft is needed, running parallel with the motor. BMW’s design doesn’t have this. Instead, there’s a planetary gearset (labeled “20” in the drawings) mounted directly behind the motor, reducing the output shaft speed while keeping it in line with the motor’s main shaft. It’s a clever layout that adds simplicity, and although it doesn’t appear to have been used on the E-Power Roadster, it’s very possible that the planetary gear design hides under the futuristic skin of the Vision DC Roadster.

An older patent showed BMW also using a more conventional motor layout with an overall shape similar to its F-series models. (BMW Motorrad/)

BMW patented another electric bike design back in 2019 with a more conventional transverse layout, having a shape and dimensions that matched the F-series models—which also implies that BMW is working on electric machines that mimic at least two of its existing gas-powered ranges.

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