Thread by @fastestlap_f1

The brake-bias is one of the adjustments more often tweaked by the drivers🕹

The 5️⃣7️⃣.0️⃣ in the picture means the front brakes will have 57% of the braking force and the rears the remaining 43%.

But do you 🫵🏼 know does it really work? Let's discover it! 🧵🏎 #F1Tech

(You might benefit from some technical concepts explained here ⤵️. Consider taking a read first!)

A decelerating tire needs to roll slower than the free-rolling tire rate, v/R. In this case, the longitudinal slip ratio is negative.

If the driver hits the brakes too hard 🛑, it will end up locking the tires. At first, the downforce is high and the braking force is not enough to lock them, thus longitudinal slip does not reach the peak. But as speed decreases, so does DWF, and the grip goes over the peak ⤵️.

(same video but slower!) In this video first the fronts lock and the rears follow suit. Once the tires lock, the braking acceleration drops abruptly from 4g to 1g as the tires with excessively slip barely have grip

To prevent locking, drivers progressively release the pressure from the brake pedal📉 As the speed decreases, less pressure is applied since the downforce drops.

The big difficulty is that the driver must handle the grip of both front and rear axles with only one control, the brake pedal. However, before braking, the driver can pre-set how much balance goes front and back. This is the brake bias:

If you wonder how this system is integrated in the car, check out this video by @chainbear

Now the driver has pre-set the brake bias such that front and rear tires are perfectly in balance: the maximum grip is extracted from both tires! This is the best deceleration that can be achieved (video in slowmo)

That was the best balance. What if the brake balance is +3.0%? That means that the rears do not get enough brake torque and their grip is not fully exploited. Here the car is front limited, they will lock first. The difference is subtle but hey, welcome to motorsports!

The opposite happens if the brake balance is -3.0%: more pressure than ideal is applied to the rears and the fronts are not squeezed to the maximum. The car is limited by the rear tires.

In conclusion, brake bias is used by the drivers to balance the front and rear grip extracted from the tires. The sweet spot is found when both tires are brought to their grip peak. Otherwise, the car will be either front or rear limited and less deceleration is achieved

I hope you have found this thread interesting! More details can be found in this blog entry 😊 enjoy the last Sunday without F1!medium.com/@fastestlap/ca…