Drivers and their teams constantly battle against time at the highest level of motorsport. And I'm not just talking about lap times: each race weekend they only have a few practice sessions to find the perfect setup for qualifying and the race. A setup that best adapts their bike to the nature of the track, helps get the most out of the tires on this type of asphalt and gives their rider the information they need to properly push the bike to its limits.
These famous settings that we so often hear about are in fact the combination of all the different parameters that can be adjusted on the bike. And this is where things start to get complicated, because there are a lot of variables that can be adjusted or changed. And to make matters worse, almost all of them are connected in one way or another. But how do Moto3, Moto2 and MotoGP teams manage the configuration of their prototypes?
From graph paper to spreadsheets
In the early days of motorcycle racing, motorcycles were much more basic and only had a few options to adjust the handling of the bike. Nevertheless, the technicians quickly realized that they needed to keep track of certain chassis parameters, such as the spring rate used, the wheelbase and the height of the chassis, to name a few.
With this you could rebuild a complete motorcycle and not accidentally change the way it was tuned. The resulting list became the setup sheet. It was still a pretty short list, but it was enough to help them not get lost in tracking how the bike was handling. With lap times added later, usually alongside some comments from the driver about the tires and gear ratios used, this sheet of paper was all you needed in the past.
Next came the first racing shock absorbers and forks, as well as many more possibilities in their settings. This resulted in a need to calculate the effects of these various spring/preload combinations, as well as the effects of fork oil level and springs. It was then that the first computer programs were born. When you completed this Excel-based software tool with your spring rate, preload, oil volumes, it gave you clear diagrams, showing the resulting forces per stroke.
It was extremely helpful. This allows you to know how to change the spring rate, for example, and to choose a preload suitable for each track. Without this, it's easy to end up not only with a different spring rate than the team wanted, but also likely with a different chassis height, which the team didn't necessarily want.
Useful if the rider is very happy with the bike, but the forks reach their stop during sudden braking. This is where a spring calculator tool could tell you not to change the spring itself, but to increase the oil volume instead. In short: a tool calculates the forces on your shock absorber and your fork. If you know where in the stroke you need to change the spring force, the tool will help you find the right combination of springs, preload, and return spring.
Technicians still use a configuration list, but it is now populated with numbers from their calculation tool. However, there is a limit to what such a tool can do, as it only gives the forces on the front fork or shock absorbers themselves, but not at the all-important contact point between the tires and the track. It doesn't include swingarm length, chassis height, center of gravity, just to name a few key parameters.
So if we change the final drive ratio and with it the length of the swingarm, then the same shock absorber spring will have a different effect on the wheels, and even less so when a linkage with a different ratio is used. At one point in history, this calculation tool clearly needed an update in order to meet the growing demand in motorcycle racing.
With the gradual development of the chassis, suspension components and tires, the configuration list became longer and longer because, aside from the previously mentioned variables, teams found themselves with many more choices. Such as adjustable caster angle, adjustable swing arms, several triple clamp offsets or at the shock absorber links.
From Excel to complex geometry software
To date, many more numbers had to be kept track of and with that, full parameters had to be simulated. That's when the simple tool evolved into full-featured geometry software, better known as the Chassis Tool.
A chassis tool can be thought of as a virtual model of the motorcycle's chassis and suspension, with the added benefit of calculations and comparisons. To do this, the program must be fed with all the dimensions of the chassis, swingarm linkage, triple clamp, etc. It's different from a CAD program, and with an interface that displays the relevant information we need to see when making tuning decisions. Basically, it breaks down a motorcycle's setup in numbers, so that every modification you plan to make can be simulated in advance to ensure you get the desired result.
With the increasing complexity of modern racing motorcycles, crew chiefs spend a lot of time behind their computer screens, checking numbers and comparing setup options. The crew chief and mechanics always have a list of basic setup and adjustments. They use it as a research sheet for how the bike is handling at a specific time. Each change is first made in the chassis tool, to calculate the desired result. From there it is printed as a configuration list for the mechanics to tune the motorcycle from.
In the second part of this article, we will discuss an example, but also how the teams combine the chassis tool with data analysis.
