Quote:
Originally Posted by akima
Imagine a road that is clean, smooth and has an even surface. You approach a corner on this road with your throttle even and steady. You don't apply any acceleration and you don't decelerate as you take the corner.
On bike designed with perfectly balanced weight distribution between the front and rear, I'd expect the front and rear tyres to share the grip requirement evenly: 50/50. The rear tyre would likely be a wider tyre with a bigger contact patch so it would be capable of maintaining more grip than the front tyre. So if you take the corner I described at such a speed that you reach the traction limit of the bike then I would expect the front wheel to give-out first as the front tyre is thinner (smaller contact patch).
What I've been told is that you should accelerate through the corner in order to move that 50/50 weight distribution I mentioned above towards more of a 70/30 (rear/front) weight distribution.
Something I struggle with is the fact that if you accelerate through a corner, although you are shifting weight to the rear (taking grip-demand off the front and transferring it to the rear), you are also increasing the size of the rear-tyre contact patch and decreasing front-tyre contact patch. So although you are taking grip-demand off the front (by reducing weight) you are also taking grip-capacity off the front (due to the shrinking front contact patch).
Is it the case then that that changing of the size of the tyre contact patch makes far less difference than the effect of transferring weight front one tyre to the other? If the opposite was true and the contact patch made more of a difference than the weight distribution, then presumably the advice would be to decelerate as you go around a corner in order to increase the size of the front wheel contact patch.
Based on what I've written does it sound like I understand this all correctly? (I know that my terminology isn't great)
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Yes, this is accurate. By shifting weight to the rear you’re making the front tire less loaded, the front tire has a smaller contact patch, and the bike is harder to turn. I believe the reason that this is suggested is due to several assumptions: 1. The rider is riding well below the traction limit of the tires so the loss of traction is outweighed by the benefit of increasing chassis stability. 2. The rider is not in a decreasing radius turn. 3. The rider is not heading downhill.
Rolling on the throttle throughout the turn increase chassis stability by altering the geometry of the bike. That advice works well in these situations -
1. Set entry speed while straight up and down
2. Initiate turn until you’ve reached the desired lean angle
3. Roll on throttle throughout the duration of the turn.
The benefits of this method is that it forces the rider to think about entry speed prior to the turn. It provides a discrete set of events that need to be accomplished in series. It’s easy to understand and to learn. It creates a stable bike geometry in the turn. The negatives to this method are what you’ve already pointed out. It reduces the front contact patch and reduces the immediate ability for the front tire to take on load. Which temporarily reduces the rider’s options to react to an event that happens mid turn.