THINGS YOU NEED TO KNOWÉ
The Mupo Magneto system controls the damping force with MR fluid which comes from US firm LORD and contains tiny iron particles. When you pass an electrical current through the fluid using electro-magnets built into the suspension units, the alignment of the particles increases or decreases the viscosity, stiffening or softening the suspension damping and feel in milliseconds.
The standard Magneto system has just one power cable from the battery to the ECU and two wires from the ECU to the shock and one fork leg (the other fork leg simply has a matching spring). The ECU is monitoring and controlling the damping force 1000 times per second, but the MR fluid is two to three times slower, but that is still a matter of milliseconds. However, the feedback from even the fastest bike encountering a bump in the road is 20-50 times slower, so response time isn’t the challenge – it’s how the system responds.
It’s about control
Rapid control of the damping force is one thing, but it has to respond to road conditions. A standard set-up has pretty fixed damping, linked to the spring rate.
This system senses the movement of the chassis and the speed of the suspension units themselves to fine-tune the damping in real time.
This gives the bike a much larger range of damping forces, which massively increases the usable range of a standard spring. That means your sportsbike can have the soft characteristics of a tourer on cobbles, but then have the firm control that you expect at speed.
Feel your way
For back-to-back testing, Mupo used two identical Moto Morinis running the same springs, with one on the standard manual set-up, the other using the Magneto system. The Magneto system calms down the movement of the bike, so that there isn’t so much pitching back and forwards. For the first five minutes it feels unusual, but after that the test rider reported a feeling of greater stability.
The road-going system is based on sensors that measure the movements of the frame. For racing it is possible to add two linear sensors (potentiometers, commonly used in the racing) to improve the control, based on the suspension velocities (front fork and rear shock). The suspension velocities are worked out by the ECU, which processes the data from the suspension positions, as measured by the linear sensors.
The system also has the potential to manage chatter. Chatter usually has a frequency of 16-17 hertz and standard suspension’s 50 millisecond response time means it struggles to cope.
The Magneto’s millisecond response means it can finetune the damping so those forces aren’t transmitted to the rider. However, current regulations limit its use in prototype classes like Motogp and until it is fitted to street machines and homologated it can’t be used in production classes either.