MotoMatters.com | Kropotkin Thinks

Luca Marini's practice start at Mandalika shows just how low the MotoGP bikes are during the start. Front and rear ride-height devices engaged means the fairing is just a couple of centimeters above the ground. That is exactly how you would expect a drag racer to look: with the weight as low as possible, weight transfer is restricted, and wheelies are hugely reduced.

The Yamaha is pretty low too. Everyone has devices to lower the front at the start. Even Darryn Binder, on last year's Yamaha M1.

Johann Zarco at the start, with the mix of brand new fairing and older tail section. There is rarely time to paint up the new bikes at the test, so sticker kits with sponsor names have to do.

Luca Marini is very tall for a MotoGP racer (1.84m) but when the bike is squatting down in the launch position, he looks huge. This is the GP22, with the single butterfly switch for both front and rear ride-height devices he is operating.

The old front holeshot device on the Ducati GP21. This one has a production date of 23.02.21 stamped on it. The rotating wheel is operated by a cable to the switch on the top yoke. Behind the wheel is a catch, which is rotated to fit into the latch on the metal bracket protruding from the fork leg outer tube. The latch locks it in place for the start, and springs back when the rider brakes for Turn 1.

The GP22 holeshot device is different. The latch bracket is located at the rear of the fork leg, attached to the fork bottom. It is made of carbon fiber, rather than aluminum, as it is unsprung weight. The latch fits in a hole at the back of the fork cover.
The holeshot device is separate to the front ride-height device, though the ride-height device is used to lower the bike so that the holeshot device can engage. The front ride-height device is barely visible in this photo. Zoom in and you can just see the rod which extends from the fork bottom into the pneumatic cylinder at the front of the fork leg. This is a little clearer on the hi-res version available to subscribers than the standard resolution version.

Aprilia's version of the front holeshot device is just visible on the right fork lower. You can just see the catch which is activated by a cable. Also visible at the bottom is a McLaren accelerometer, used to log the precise motion of the fork leg and front wheel axle. These accelerometers are used all over the bike, wherever teams are trying to measure the forces and movements of specific parts.

A better look at Aprilia's front holeshot device. The cable used to engage the device is clearly visible. The latch engages with a plate on the fork upper, just visible between the carbon outer fork and the gold fork seal retainer.

The GP21 office. On the right clipon, inboard of the throttle, at the bottom the lever for engaging neutral, needed for the seamless gearbox, and at the top, the button in the big red socket is the kill switch (protected so it doesn't get activated accidentally.
On the top triple clamp, the two butterfly switches for engaging the holeshot devices at the start, front on the right, rear on the left.
On the left clipon, the three Playstation-style buttons are traction control, engine braking, and pit lane limiter. The big lever underneath the clipon is the thumb brake. And the rocker switch is a device adapted from a mountain bike dropper post switch, which operates the rear ride-height device. Press on corner entry, and the system figures out itself when to lower the rear on corner exit, based on the pitch and attitude of the bike.

The Yamaha keeps its electronics at the back of the bike. The spec Magneti Marelli ECU is the box under the seat marked with FQ-1 (telling you this is Fabio Quartararo's bike #1). At the rear is another control unit, marked V10+ Canfail.

It is unusual to catch a bike with the fairing off. The Yamaha of Darryn Binder uncovered here, with the frame clearly visible. Note the engine mount: the mount point is very low, and the mount section is wide and made of thin material, in pursuit of just the right flexibility. This is part of the reason why the Yamaha goes round corners so very, very fast.

Of course, if a rider throws the bike into the gravel, then everything can end up exposed. You can see how sharp the stones in the gravel traps at Mandalika are by the scratches on the frame. Also visible is Yamaha's steering damper, one of the last factories to still use a linear rather than rotary damper. The two gold-colored canisters near the front wheel may either contain the compressed air that power the ride-height device, or possibly the system which triggers its deployment.

The Aprilia RS-GP's elegant tail, with upper exhaust, which is longer and has changed design from last year. The tail is believed to contain a mass damper, like the Ducati. But these box units on the rear of the tail have been getting smaller and slimmer over the years.

The Aprilia aero package of Aleix Espargaro, identifiable by the three hand prints of his wife and two children. Aprilia have commonly used pitot tubes on the front of the fairing, to measure air speed and pressure. The front fender also a small louver at the front, presumably to reduce turbulence around the wheel. The fender itself covers a long of the fork lowers in an attempt to reduce drag. This is one area which varies widely from factory to factory

KTM's aero package. These are the older style wings, though KTM also tried a set of double wings. The lower side pods are new for this year, following Ducati's example. The gap between fairing and air intake reduces turbulence in the intake, smoothing the airflow and improving airbox pressure.

The apparent simplicity of the Suzuki GSX-RR is always what catches the eye. It is neat, uncluttered, unfussy in its details. The narrow frame section just above the swingarm pivot point is a key part of the bike's ability to carry corner speed. Suzuki had a revised frame at Mandalika and Sepang, which met with approval. But the changes are always so subtle that they are always almost impossible to spot.

Ducati's funky long exhaust which was used a lot at Sepang. The upper exhaust is also a fraction longer than the GP21, and the exhaust torque valve has been moved too. Though tested extensively, by Mandalika, it appeared that Ducati had decided against using and switched back to a more traditional stubby design.
Note the lack of swingarm spoiler. The swingarm spoiler disappeared, along with the rear wheel covers, after the summer break last year, when Ducati also introduced the automatic rear ride-height device. The spoilers were already starting to cause problems with ground clearance, and the automatic ride-height device was lowering the bike earlier and lower. The spoiler (ostensibly a "tire cooler") also helped keep the rear wheel on the ground. The rear ride-height device places more load on the rear, which achieves the same objective.

Rear view of the Ducati. The 'salad box' containing the mass damper has become smaller and smaller, and is quite slim now. What that means in terms of mass damping, or even function, is unclear.
The fuel tank is also clearly visible under the seat. The increasing use of ride-height devices has had a major impact on the shape and location of the fuel tank. The rear wheel needs a lot more room, and so the tank has been shifted forward and, as is visible here, shaped to accommodate the rear wheel.
 

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