Honda's new three-motor drive technology By Ben Purvis
Honda's tradition of pushing radical new ideas in motorcycling is being upheld with a new development project for a future three-motor electric bike and with the E-Clutch system that reaches showrooms in 2024.
Patent applications have emerged showing a development of the radical Riding Assist-e electric concept bike, (which debuted in 2017 with computer-controlled steering and a variable steering head angle to change the wheelbase), allowing it to balance itself even without a rider aboard. The new development of the idea takes the concept of rider assistance a step further by adopting as many as three electric motors - two powering the rear wheel and a third driving the front - to create an unprecedented level of computer assistance while leaving the rider in control.
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On the face of it, having two motors powering the rear wheel, with one chain final drive on each side, seems illogical. After all, the wheel is going to turn at the same speed as it would with one motor and chain driving it. But Honda isn't thinking about the drive that the motors provide - the focus here is on the influence that they have on the bike's balance. Both motors are mounted longitudinally but turn in opposite directions. Anyone who's ridden a boxer BMW, a Gold Wing or a V-twin Moto Guzzi will know that the torque reaction of a longitudinal engine will try to tilt the bike as you rev it, and that's exactly the effect that Honda is using here.
In normal use, both rear motors work together and because they counter-rotate, they cancel out each other's torque reaction. However, Honda envisages using that torque reaction, modulating the torque from the two motors to help the bike tip into corners faster and to stand it back up again on the way out of them. The left motor, turning clockwise, will tug the bike over to the left if used on its own. The torque from the right motor, turning counter-clockwise, tilts the bike to the right. So, by juggling the torque from both, the electronics can influence the bike's lean angle.
'E-clutch reaches production'
The third motor, mounted in the front wheel hub, uses the same phenomenon. With both wheels on the ground, it helps spread the total power output across the two tyres, making the most of their potential traction, but Honda also believes it will be useful under hard acceleration when the front wheel lifts.
With the wheel in the air, reverse torque is used on the front motor, creating a reaction that tries to bring the nose back down again, allowing the bike to accelerate faster without flipping over backwards.
While that piece of drivetrain technology is clearly still years away, Honda's E-Clutch - introduced on the 2024 CB650R and CBR650R but likely to be adopted across many more bikes in years to come - will be available by the middle of next year.
It's perhaps the simplest and cleverest attempt yet to make a semi-automatic transmission, using a computer-controlled servo motor to operate a completely standard clutch while retaining the normal bar-mounted lever and cable operation, allowing it to be overridden at any time or switched off entirely if you'd prefer conventional clutch operation.
Adding just 2 kg to a bike's weight, the E-Clutch features two small electric motors and a set of reduction gears, all mounted inside the clutch cover and attached to the conventional clutch linkage, allowing a normal cable or hydraulic clutch system to be retained. Pulling the bar-mounted lever overrides the electronics, leaving the rider in ultimate control, and gears are still shifted using the normal, mechanical left foot lever.
When active, the E-Clutch is controlled by its own ECU, taking information from the bike's speed, revs, throttle position and gear position. A quickshifter-style load sensor on the gear linkage tells the system when you want to change ratios, and there are three settings - hard, medium and soft - to change how much pressure is needed on the manual gear shift before the clutch operates. Come to a halt and the clutch automatically dips to ensure the engine doesn't stall, and when the system is active pulling away from a standstill, it is simply a case of engaging first gear and opening the throttle. The E-Clutch does the rest, ensuring a smooth getaway and preventing any chance of a stall.
Since the system is also tied into the engine's ride-by-wire throttles, the injection and the ignition, it promises to make up- and down-shifts faster and smoother, and an on-dash display will show if you're in too high a gear and should change down.
Simpler, lighter and cheaper than Honda's DCT semi-auto gearbox, and able to be fitted to virtually any bike without major changes to the existing transmission and clutch, there's every chance that the E-Clutch will be offered across a huge part of Honda's range in years to come.
