Why do the rules mandate 8-speed gearboxes?

[DChemTech]

I know absolutely nothing about gearboxes, but I do find the question intriguing;

how many gears do you think (most teams) would end up with if they were free to choose, given the restrictions that they cannot change the ratios throughout the season, and can't opt for some continuous system. Would 8 be the optimum? Would they settle for less, considering power delivery of the current PU? Or maybe a couple more, despite the extra work for the driver?

[Just_a_fan]

Watching some onboards, the drivers brake for a slow corner and don't flick down the gears till quite late in the braking phase. As they use energy recovery rather than engine braking, there's no benefit to changing down as you slow in the old fashioned sense.

At the point of downshift, there's a quickfire number of paddle pulls and then turn in and back on the power before the apex in many cases.

As for number of gears, as they're driver operated, the ideal won't be the mechanical ideal. As previously mentioned by someone, you'd have dozens of gears which you worked through quickly. That way the engine was always generating maximum output. But a driver would get lost in 24 gears.

I'm sure the teams would like 9 gears, however, to give the option of a Monza/Kemmel Straight higher top gear, used only on long straights where downforce isn't too high. Or maybe the current 8 is actually pretty much spot on for these PUs.

[hollus]

The PU design is a compromise taking into account that drivers use a range of about 2000rpm in normal operation.
If they could run more gears, then the PUs would be optimized to produce slightly more power in a narrower rpm band at the cost of lower power outside of it.
But then they might find it worth it to run even more gears to optimize for an even narrower rpm band, at which point they could add extra gears...
Ultimately the limit would be just the compromises of weight and bulk of the gearbox, leading to a huge cost race.

But the fact that no PU manufacturer has renounced the use of any gear since 2014 suggests that the ideal number would be higher than 8, as having “dummy” gears would likely allow for a narrower gearbox. But no one took the option.

[hollus]

By the way, 1st gear has been little more than a launch gear since 2014. But then launches are the best opportunity to gain or lose places in the whole race, making that 1 second per race usage rather crucial. It might be used again for another second when starting from the (usually single) pit stop.

[henry]

Watching some onboards, the drivers brake for a slow corner and don't flick down the gears till quite late in the braking phase. As they use energy recovery rather than engine braking, there's no benefit to changing down as you slow in the old fashioned sense.

There’s actually a loss. Energy consumed by engine braking is energy not recoverable by the K. They can allow the engines revs to drop until the MGU-K max torque is reached.

[Big Tea]

With the barrel shift mechanism there is no option to skip a gear; the barrel has to rotate and initiate the next gear in the sequence. That's not to say you have to stay in that gear for long though......

I have had a couple of motorcycles with 'neutral finder' on. 1 press and it is in 'N' (between 1st and 2nd)

[DChemTech]

The PU design is a compromise taking into account that drivers use a range of about 2000rpm in normal operation.
If they could run more gears, then the PUs would be optimized to produce slightly more power in a narrower rpm band at the cost of lower power outside of it.
But then they might find it worth it to run even more gears to optimize for an even narrower rpm band, at which point they could add extra gears...
Ultimately the limit would be just the compromises of weight and bulk of the gearbox, leading to a huge cost race.

But the fact that no PU manufacturer has renounced the use of any gear since 2014 suggests that the ideal number would be higher than 8, as having “dummy” gears would likely allow for a narrower gearbox. But no one took the option.

Thanks, I would expect something like that indeed. I wonder how many more gears a driver could realistically deal with before simply getting lost in shifting.

[rscsr]

The PU design is a compromise taking into account that drivers use a range of about 2000rpm in normal operation.
If they could run more gears, then the PUs would be optimized to produce slightly more power in a narrower rpm band at the cost of lower power outside of it.
But then they might find it worth it to run even more gears to optimize for an even narrower rpm band, at which point they could add extra gears...
Ultimately the limit would be just the compromises of weight and bulk of the gearbox, leading to a huge cost race.

But the fact that no PU manufacturer has renounced the use of any gear since 2014 suggests that the ideal number would be higher than 8, as having “dummy” gears would likely allow for a narrower gearbox. But no one took the option.

Thanks, I would expect something like that indeed. I wonder how many more gears a driver could realistically deal with before simply getting lost in shifting.

Especially for downshifting, downshifting like on race bikes could work. They basically work by having more than 1 clicks. I.e. a "full pull" on the lever shifts between 2 (Shimano 105) and 5 gears down (Campagnolo Ultra-Shift).

[hollus]

In motorbikes they climbed their way to 14 gears, but of course those were much slower laps so potentially more time between shifts.

1967 Suzuki RK67 50-2

If the RS67 125 was sophisticated, so too was its 50cc little brother. The RK version was a similarly liquid-cooled two-stroke, but this time a parallel twin instead of a square four. It revved to a maximum of 17,500rpm and, through its mind-boggling 14-speed transmission, was capable of a maximum speed of 170kph. All enough for the three-strong works team of Hans-Georg Anscheidt, Yoshimi Katayama and Brit Stuart Graham to dominate the championship, placing 1-2-3

[Big Tea]

The PU design is a compromise taking into account that drivers use a range of about 2000rpm in normal operation.
If they could run more gears, then the PUs would be optimized to produce slightly more power in a narrower rpm band at the cost of lower power outside of it.
But then they might find it worth it to run even more gears to optimize for an even narrower rpm band, at which point they could add extra gears...
Ultimately the limit would be just the compromises of weight and bulk of the gearbox, leading to a huge cost race.

But the fact that no PU manufacturer has renounced the use of any gear since 2014 suggests that the ideal number would be higher than 8, as having “dummy” gears would likely allow for a narrower gearbox. But no one took the option.

Thanks, I would expect something like that indeed. I wonder how many more gears a driver could realistically deal with before simply getting lost in shifting.

Especially for downshifting, downshifting like on race bikes could work. They basically work by having more than 1 clicks. I.e. a "full pull" on the lever shifts between 2 (Shimano 105) and 5 gears down (Campagnolo Ultra-Shift).

They can not have an automatic change, but could they have a system that set the 'home' to a predicted by gps or learned position and a single press of a 'home ' button sets the default there and one flick by the driver stops there?

[DChemTech]

In motorbikes they climbed their way to 14 gears, but of course those were much slower laps so potentially more time between shifts.

1967 Suzuki RK67 50-2

If the RS67 125 was sophisticated, so too was its 50cc little brother. The RK version was a similarly liquid-cooled two-stroke, but this time a parallel twin instead of a square four. It revved to a maximum of 17,500rpm and, through its mind-boggling 14-speed transmission, was capable of a maximum speed of 170kph. All enough for the three-strong works team of Hans-Georg Anscheidt, Yoshimi Katayama and Brit Stuart Graham to dominate the championship, placing 1-2-3

That sounds like quite a handful! But indeed, more time between - and also less other settings (engine mapping, diff, brake balance, etc.) to play with I presume.