Astemo has developed the world's first height-adjustable front fork with a built-in gear pump and other systems. Combined with the rear fork, it lowers the vehicle height more quickly when stopped than conventional models. We test-rode this "HEIGHTFLEX" system and the second-generation electronically controlled suspension "SHOWA EERA Gen2". Another highlight is the low-cost electronically controlled suspension that can be retrofitted to scooters and small-displacement motorcycles.
- [Commentary 1] The new HEIGHTFLEX uses a gear pump to lower the vehicle height in about 1 second and raise it in about 6 seconds.
- [Commentary 2] EERA Gen2 with built-in control system for easy retrofitting
- [Test Ride Impressions 1] The second generation EERA has a more intelligent control mode that leaves a good impression
- [Test Ride Impressions 2] A quick, natural and natural ride height adjustment system
[Commentary 1] The new HEIGHTFLEX uses a gear pump to lower the vehicle height in about 1 second and raise it in about 6 seconds.
Astemo is a Japanese mega-supplier formed in 2021 through the merger of Keihin, Showa, Nissin, and Hitachi Automotive Systems. On May 30, the company held the Astemo Tech Show 2025, a technology presentation and test ride event for the media, at a test course in Tochigi Prefecture, where it unveiled a number of new technologies.
This article is the second to introduce the event. We would like to provide an explanation and test ride report on the evolved vehicle height adjustment system "HEIGHTFLEX" and the electronically controlled suspension "SHOWA EERA Gen2" (See the first article on stereo cameras here).
I test ride a test motorcycle equipped with the new HEIGHTFLEX and SHOWA EERA Gen2 at Astemo's Shioya test course in Tochigi Prefecture.
Astemo is a pioneer in motorcycle height adjustment and has been developing it for about 15 years. The height adjustment mechanism "Adaptive Ride Height" installed on Harley-Davidson Pan America in 2021 is based on HEIGHTFLEX. It is an innovative system that lowers the seat height when stopped and automatically raises the vehicle height while riding, achieving both foot reach and riding performance.
Harley-Davidson's Pan America 1250 Special is equipped with an electronically controlled suspension + height adjustment system based on EERA and HEIGHTFLEX. The height adjustment of the BMW R1300GS is made by Sachs.
At EICMA 2023, the company announced an evolved version of the "Gear Pump Driven Suspension Spring Adjuster" for rear suspension, which can quickly raise the vehicle height by using a motor-ridden gear pump. The system that repurposed the hydraulic pump of the ABS modulator announced at EICMA 2022 used the stroke of the vehicle's own weight, so it took time to raise the vehicle height. On the other hand, the new system shortens the time to return to the original height to about 6 seconds, about half of the conventional time.
In addition, at EICMA 2024, the world's first gear pump height adjustment system will be built into the front fork. HEIGHTFLEX is effective even with only the rear, but the benefits can be maximized by equipping the front and rear suspensions with high-speed height adjustment functions.
The lowering amount when stopped is about 50 mm for both front and rear. The vehicle height can be lowered more than when only the rear is used. The operating time when raised is about 5 to 7 seconds, and when lowered it is only about 1 second.
Another benefit is that by incorporating front and rear vehicle height adjustment, problems with the light axis can be eliminated. Conventionally, if only the rear suspension was lowered, the light axis would point upwards, but this is eliminated by lowering the front vehicle height as well. Also, depending on the settings, it is possible to control the vehicle posture while riding by lowering the front or rear.
A small gear pump, hydraulic jack, and stroke sensor are built into the outer tube. Hydraulic piping and sensors outside the fork have been eliminated. Can be installed on inverted SFF forks with an inner diameter of 43mm or more.
Rear hydraulic pump unit. The cylinder is mounted on the outside of the damper, and can be combined with the EERA electric suspension.
This is the gear pump. It is a motor-ridden hydraulic pump that can raise the vehicle height much faster than conventional products.
[Commentary 2] EERA Gen2 with built-in control system for easy retrofitting
Electronically controlled suspension (also known as semi-active suspension) detects road conditions and automatically varies damping force in real time. The "SHOWA EERA Gen2" is the second generation of electronically controlled suspension, and is the world's first system to have a miniaturized ECU built into the suspension.
By integrating the control ECU unit of the actuator that varies damping force with the suspension, electronic control is achieved without having to install a separate ECU. In other words, there is no need to install an ECU for suspension control on the vehicle body, which simplifies wiring and reduces weight. The small ECU is even equipped with an IMU (inertia sensor), making it possible to omit the stroke sensor.
This integrated structure makes it possible to convert scooters and small-displacement vehicles, which have limited mounting space, into electric suspension, which is a dream come true. They are also considering retrofitting it to existing motorcycles.
Of course, it is also compatible with large sports. The new valve structure reduces the number of parts and achieves a wider range of damping force variation than the first generation SHOWA EERA. By changing the program within that wide range of variation or installing a new stroke sensor, more precise control is possible. This means that it will be possible to equip models in a wide range of categories and price ranges with electric suspension.
EERA Gen2 front forks and rear shock. The rectangular parts on the top of the forks and under the rear suspension are actuator-integrated ECUs, and there is no wiring as is common with electric suspensions.
EERA Gen2 rear shock. The green part is the printed circuit board stroke sensor, which is revolutionary in that it is cylindrical and can be wrapped around the outside of the damper.
The EERA Gen2 rear suspension installed on the G310R. It is not only suitable for large vehicles, but also for low-cost models such as small-displacement vehicles and rear-only models. Also, it is possible to convert to an electric suspension just by replacing the suspension.
[Test Ride Impressions 1] The second generation EERA has a more intelligent control mode that leaves a good impression
The test vehicle was a Ducati Multistrada V4S. For the test, it was equipped with Astemo ride height adjustment and electronically controlled suspension.
The left side of the front fork is equipped with the HEIGHTFLEX ride height adjustment system, which has a built-in gear pump, and the right side is equipped with the EERA Gen2 electronic suspension. The rear suspension is also equipped with a motor pump unit for ride height adjustment and the EERA Gen2. The base of the front fork is the SFF-BP. The ability to separate functions between the left and right forks is a benefit unique to the SFF-BP base, which separates the dampers and springs from the left and right sides.
The test vehicle was the Multistrada V4S. This big adventure motorcycle is equipped with a 1158cc V4 engine and has an outstanding sense of volume.
You can see the EERA Gen2 actuator-integrated ECU unit on the top of the right fork. On the left is the gear pump type HEIGHTFLEX.
The rear also uses a gear pump type vehicle height adjustment unit and electronically controlled suspension. Both the front and rear are equipped with independent actuators and integrated ECUs.
A test course that reproduces a winding road. There are continuous ups and downs, and gaps are set in various parts such as during corners.
The test ride was conducted on a test course on a wet road, and three laps were run in each of the comfort, dynamic, and active modes. The car stopped when switching modes to test the latest HEIGHTFLEX's foot placement.
The electronically controlled suspension EERA Gen2 automatically adjusts the damping force in all modes, but in comfort mode, it is soft and moves well, prioritizing comfort. In dynamic mode, the damping force is higher, prioritizing the fun of sporty riding.
To be honest, I didn't feel a big difference with my skills, probably because the road surface was wet and the damping force is appropriately adjusted in both modes. However, when going over a gap, the impact was softer in touring mode, and in dynamic mode, although the initial behavior was disturbed, it seemed to settle down quickly.
I liked the active mode. It automatically controls the damping force and vehicle posture according to the vehicle speed, and is set to always maintain optimal damping, so the shock when going over a gap is soft and settles quickly. It's truly intelligent, combining the best of both comfort and dynamic modes. It handles smoothly through large and small corners and is very comfortable.
The dynamic mode in particular was comfortable regardless of the corner radius or turning speed.
[Test Ride Impressions 2] A quick, natural and natural ride height adjustment system
On the other hand, the effect of the new HEIGHTFLEX vehicle height adjustment is very easy to see. In a normal vehicle without height adjustment, both feet can touch the ground, but the heels are raised, making it feel like a big adventure with a high seat. However, with HEIGHTFLEX activated, both feet are firmly planted on the ground, giving a very secure feeling. The vehicle body seems more compact.
This is the standard height of the Multistrada V4S (rider is 177cm tall and weighs 60kg). The seat height is 840mm, and due to the volume of the crotch area, both heels are raised.
When the HEIGHTFLEX is activated and the vehicle height is lowered, the front and rear suspensions are lowered by approximately 50 mm each. Both feet are firmly on the ground and there is ample room for bending the knees. The sense of security is on a whole different level.
When you start moving from a stopped state, the vehicle height automatically rises by about 50 mm. The operation time is about 6 seconds, but it rises without you noticing, and there is no sense of incongruity. It will not be a problem even in a situation where you turn at an intersection immediately after starting from zero.
And when you stop, the car's height is lowered smoothly. It only takes about one second, and again, there's no sense of discomfort or the suspension moving. It's so smooth that you'll wonder if the car was always this high.
I also had the motorcycle's body posture changed to lower the front and rear when it was stopped. When you want to ride sporty, you can put weight on the front wheel and lean forward, with the front lowered, and when you want to go on a leisurely ride, you can sit upright and lower the rear for comfort... I thought this might be the kind of "variable motorcycle" that could be realized.
The front vehicle height is lowered to the minimum and the rear is raised to the maximum. The front is lowered, creating a sporty body posture.
The front ride height is raised to its maximum and the rear is lowered. With HEIGHTFLEX, it seems that the range of settings can be easily expanded.
With HEIGHTFLEX, even riders who are unsure about foot placement can lower the hurdle of adventure models with high seats. Furthermore, if combined with Honda E-Clutch or Yamaha Y-AMT, which do not require clutch operation, even beginners should be able to ride with confidence. Also, electric suspension is currently only installed on large, high-end models, but the inexpensive EERA Gen2 could be installed on small-displacement vehicles.
It has not been decided whether it will be installed on commercial vehicles, but HEIGHTFLEX and EERA have already been adopted in adventure models from overseas manufacturers. There is a possibility that it will be updated to the latest gear pump type HEIGHTFLEX and EERA Gen2. We look forward to seeing how it will be adopted in the future.
