Although the electric motorcycle scene is advancing slowly, it is moving forward, and this prototype from Finland is proof of that, with its super-cool rim motor design.
The RMK E2 has an interesting chassis design, and the prototype built for Helsinki’s upcoming motorcycle show shows the reason for that: the E2 has an electric motor in the rim of the rear wheel, instead of under the rider (like most bikes) or in the hub (like some new electric bikes).
The rim motor means the rear wheel doesn’t need a hub, or spokes, and certainly provides a striking visual focus point. There’s also no chain, belt or shaft drive, just a set of heavy cables on the left-hand side of the motorcycle. The motor’s stator is on the inside of the rim, and the outer rim has the rotor, presumably an excited coil system.
So how well does the new design work? Can a rim motor actually make enough power? Turns out, peak horsepower is a relatively tame 67 hp, but the bike supposedly makes 236 lb-ft of torque. That’s considerably more than many cars on the market, and it’s all pushing a 200 kg motorcycle. Top speed is limited to 160 km/h, and the machine should reach that speed very quickly.
RMK says this bike will have a range of 200-300 km, although it’s not stated whether that’s a highway range, or mixed urban/highway riding, or all urban riding. It does make a big difference, as stop-and-go urban riding means extended range, if you have regenerative braking. Highway riding is a huge drain on the battery due to the energy required to ride at speed, and minimal brake usage means the battery is not getting continuously topped up. RMK simply says range depends on riding style and conditions.
However, RMK also says it plans on intensifying its testing program after the Helsinki motorcycle show, and that the numbers it’s already published are just its minimum goals—the company plans to work hard to exceed them. It’s already saying the bike will have one of the largest batteries available on the electric motorcycle market, and with that much space available in the chassis (remember, there’s no motor under the rider), the designers could certainly pack a huge powerplant in there. So, this is a project we’ll definitely keep an eye on, even if it’s currently priced at 25,000 Euros, or approximately $37,000 CAD.