At the recent EICMA show in Milan, Italy, Tenneco-Marzocchi kicked off a revolution in motorcycle suspension by unveiling the first aftermarket electronic active fork and shock.
Company officials humbly referred to these components as “semi-active” because all parameters are not
adjusted automatically. In fact, spring preload can only be altered manually; on-the-run electronic changes would have required gas springs, not steel coils.
Compression and rebound damping on both fork and shock are controlled by a sophisticated, fully automated digital system developed by Marzocchi’s Bologna-based R&D department in cooperation with Tenneco-Monroe, which may have the largest experience in the field of electronically managed suspensions.
A growing number of motorcycles are equipped with suspension that can be altered at the touch of a button;
BMW’s ESA/ESA II, with its fixed settings for Comfort, Normal or Sport, is an excellent example of the
genre.
Tenneco-Marzocchi’s system is far more advanced. Sensors collect information about the dynamic workings of the bike and feed them to a powerful ECU that relies on special solenoid valves to make micro-adjustments to the suspension in 10-millisecond intervals.
Included in the suite of sensors: four accelerometers, two potentiometers and an inertial platform. The
accelerometers are applied in pairs to the suspension—one on a static section (fork leg/shock mount) and another adjacent to the axles. These compact, lightweight units accurately register compression and extension values of the fork and shock and send them to the ECU.
The potentiometers are more obvious because they are small-diameter telescopic units attached to one of the fork legs and upper/lower shock mounts. They copy suspension travel, supplying the ECU with numbers
related to amplitude and intensity of the accelerations as they correlate to riding style and condition of the surface on which the bike is traveling.
Finally, the inertial platform has a 16-bit processor that takes information coming from three gyroscopes
and accelerometers that constantly monitor performance (acceleration, deceleration and speed), attitude and consequent loads the bike must handle (lean angle around corners, for instance) and wires those to the ECU, as well.
All this information is funneled to a fully integrated monitoring system that sends commands to the valves
to adapt the dynamic response of the bike to the variables of the riding situations—all in the name of
performance, comfort and, above all, safety.
The system was conceived to offer three modes of interface with the rider. In reality, the most basic of those three modes has no interface at all. The system is set at the factory to actively modulate suspension settings by comparing the data collected by the ECU to the range of algorithms stored in its memory. In this mode, the range of settings should be more than adequate, depending, of course, on the type of motorcycle, its performance potential and versatility.
Mode 2 is based on a range of settings (usually three) from which the rider can select the one he or she
decides will likely be the most effective in a given situation. The system still modulates suspension response over a broad range of damping settings, but it starts from the most basic parameters relative to the selected setting.
The third mode lets the rider interface openly with the ECU. Software allows the rider to dialog with the
ECU through a window in which the damping-response curves are clearly represented and can be modified
with a laptop, tablet or smartphone. Here, the setting can be accurately personalized to a narrower range of specific response characteristics. This will be valuable for racetrack use because the setting can be linked to a GPS (included in the electronics suite) to modulate suspension action one section of the track at a time.
Tenneco-Marzocchi is offering its active-suspension system on its entire range of inverted forks, from 40 to 50mm, on its conventional forks with 40 to 45mm stanchions and to a new generation of shocks sporting 36 and 46mm piston diameters.
A final note: Tenneco-Marzocchi chief project engineer Enrico Pezzi recently developed a pressurized
sealed-cartridge damper for the RAC 50 Light fork. For the new “active fork,” however, he used an open-
cartridge damper, since it offers a wider range of modulation, instantaneous response, lower friction
and, above all, the same feeling of a conventional fork, but with all the benefits of the digital-damping
management system.
