The eyes of the MotoGP world have been on Ducati over the past few months, as they have rolled out new and surprising (not to mention controversial) engineering ideas on the Desmosedici GP19. At the Jerez test, there was an aerodynamic seat, and a brake torque arm connected to the rear chassis, and more.
But up until four manufacturers protested Ducati's use of an aerodynamic spoiler attached to the swingarm during the first race of the season at Qatar, all the talk had been of Ducati's so-called holeshot device. It first came to public attention when Ducati riders were spotted stopping at the exit of pit lane at Sepang, and twisting a lever on the top plate of the triple clamp (shown below) before practicing their starts.
With fans and media alerted to its existence, TV cameras started keeping an eagle eye on the Ducatis, focusing closely every time they made a practice start. Each time we saw one, we learned a little more. That the lever took some effort to engage. That the riders were compressing the suspension when they stopped, to make it easier to twist the lever. And that the rear of the bike was significantly lower when the holeshot device was engaged.
Public knowledge of the holeshot device also confirmed earlier rumors which had been doing the rounds of the paddock. As more information leaked out, we could start to piece together a history of the part's development, and how it worked. And now, I have come into possession of a photograph of the holeshot device.
Naturally enough, I turned to friend and technical guru Peter Bom for advice and explanation. Former world championship winning crew chief, Peter has a keen intelligence and an excellent understanding of what a racing motorcycle can do, and should do. He explained to me what he thought the holeshot device was, and how it worked. The information below is based on his analysis of what he can see in the photo.
But first, some history. The holeshot device made its first appearance at the Motegi round last year, where Jack Miller used it on his Pramac Ducati. Miller used it for the rest of the season – with the exception of Phillip Island, where the braking for Turn 1 is not severe enough to disengage the mechanism after the start – and in 2019, it has now appeared on all of the Ducati GP19s, at the very least.
The device functions as follows: before the start of the race (or before a practice start), the rider uses their weight to compress the suspension, then twists the lever to engage the mechanism. The mechanism then locks the rear suspension in a lower position for the duration of the start. When the rider arrives at the first corner, and brakes hard before entering the turn. That hard braking causes the rear to lift, which in turn triggers the unlocking mechanism, which frees the device and returns the rear suspension to its normal operation.
It is something of a surprise that Ducati's holeshot device locks the rear suspension down, rather than lifting it up. Holeshot devices are common in motocross, but there, they lock the front forks down, rather than up. The idea there is to keep the front lower to help prevent wheelies, making it easier to control the bike off the line.
But Ducati's device appears to do the opposite, lowering the rear, rather than the front. Much to the surprise of Peter Bom, who had expected a holeshot device to focus on reducing wheelie.
That the device lowers the rear suggests to Bom that it serves a slightly different function, and that Ducati is not looking to reduce wheelie, but rather to increase rear grip. By lowering the rear of the bike, they place more weight on the rear tire, creating more mechanical grip. The fact that the Ducati is longer and lower than most other MotoGP bikes (also the reason the bike still suffers from understeer) may explain why Ducati is searching for rear grip, rather than trying to reduce wheelies.
So what exactly is this device? The photograph (shown below, for subscribers only) which came into my possession shows that the device is what looks like a miniature shock absorber which sits in the place where the suspension link would normally. The adjustable link (see the bottom of the page) is replaced by either a hydraulic or mechanical cylinder assembly, which joins the bottom of the suspension linkage to the swingarm. It looks like a hydraulic or mechanical actuator.
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Two things are visible in the photo. First, the piston / plunger. This is clearly an actuator, the mechanism which helps to change the length of the suspension linkage before the start, lowering the rear of the bike. The second, on the right, is a spring, which presumably operates the return mechanism.
When the rider turns the lever on the triple clamp, that must move the pushrod inside the cylinder to shorten the linkage and lower the rear. That, in turn, must put the spring under tension, which releases the mechanism under hard braking.
While the device is clearly the fruit of some highly innovative thinking. It also raises some questions. The link plays a vital role in managing the suspension ride height, and is subject to significant forces. After the holeshot device has been released after braking for the first corner, the system has to return to the position it was set up for, and remain there. It should not shift, changing the ride height which the team have settled on during practice. This means that Ducati have to be certain that the device will lock solid again after it has been released.
The addition of this actuator to the suspension linkage opens up some intriguing possibilities. In theory, it would be possible to adjust ride height during the race. However, as electronic adjustment of the ride height is explicitly banned, it could only be adjusted manually, or via mechanical/hydraulic adjusters.
Will other manufacturers follow suit? As Peter Bom points out, this device lowers the rear, rather than raising it, adding grip rather than reducing wheelie. For most other manufacturers, controlling wheelie at the start would be much more important, meaning their device would have to do the opposite to Ducati's holeshot device. That would make releasing the rear under braking much more complicated, as it would already be extended before the rider started braking. Discerning when to release the mechanism would be much more difficult.
Here is what a standard suspension link looks like, courtesy of Tom Morsellino of Offbikes:
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