My last two blogs have focused on the braking and throttle control aspects of riding smoothly; this week, I will look at how the same concepts can be applied to cornering and lean angle to maximize corner speed.
When braking for a turn, the important parts to consider are a smooth, quick initial application of the brakes to maximum stopping force, constant brake pressure and deceleration through the braking zone, and a smooth release of the brakes entering the corner. These parameters can be evaluated by looking at brake pressure and/or actual deceleration using data acquisition.
When it comes to cornering we generally look to lateral acceleration as a measure of performance. The required rider input, and an easy way to visualize lateral acceleration, is through lean angle – for more lateral acceleration (and cornering speed) you must have a greater lean angle.
There are several aspects of a typical turn to consider. Entering the corner, lean angle should go smoothly from vertical (zero degrees) to maximum lean. Here we are not looking for a quick transition; the rider must add lean angle as the brakes are released entering the corner, and how quickly this happens depends on a number of factors.
In the middle of a long, sweeping corner, lean angle should remain as constant as possible at a maximum value – you should aim to not lift the bike from maximum lean at all until the exit of the turn.
At the exit of a corner, we are again looking for a smooth transition from maximum lean to vertical as the power is applied; again, how quickly lean angle changes here depends on how quickly the rider wants to apply the power and, in many cases, simply the rider’s style.
In a chicane, the transition from side to side – referred to by roll rate – is ideally as quick as possible; on flat pavement, roll rate is typically 60 degrees per second or better.
The graph shows data for a rider through a left/right/left chicane; the black trace is speed with labels on the left, and the red trace is lean angle with labels on the right. As the rider enters the chicane at about the 7200-foot mark, lean angle increases to about 50 degrees. As the rider transitions from left to right at approximately 7800 feet, lean angle quickly goes to zero and back to approximately 45 degrees. At approximately 8200 feet, another dip in the lean angle to zero and back to 45 degrees as the rider makes the second transition.
Note the important aspects as discussed: a smooth transition from vertical to full lean entering the chicane; a fairly constant lean angle through each turn; and a smooth transition from full lean to vertical at the exit. At each transition in the chicane, lean angle goes from maximum to zero and back to maximum smoothly and quickly.
This data is for an experienced rider but does show some details that could be improved. Ideally, the tops of the lean angle “humps” in the first two parts of the chicane would be slightly flatter across the top. Maximum lean angle in the first part of the chicane is 50 degrees but in the second and third part only reaches 43 and 46 degrees respectively. Why the difference? It could be camber or elevation changes through the chicane, but it is also typical that many riders simply don’t make it to maximum lean in transitions such as these – an oversight easily corrected once pointed out.
Roll-rate data shows how quickly the rider makes those transitions and also how constant maximum lean angle is held through long, sweeping turns. This can be calculated from lean angle or measured directly using an appropriately oriented gyro sensor. That said, it is not necessary to have an elaborate data system with a lean angle sensor or gyro to evaluate this aspect of your own riding. Many GPS-based lap timers provide lateral acceleration, from which an approximation of lean angle can be calculated and the roll rate derived.
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