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Old 10-28-2013, 05:49 AM   #69
beendog
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Joined: Oct 2013
Oddometer: 17
Quote:
Originally Posted by lnewqban View Post
You are welcome, Beendog

The throttle keeping while cornering is not as far from coasting as many believe.

According to Keith Code in his second book, all it takes is little more acceleration than coasting for the rider to be "fair" to each contact patch.

"Considering that most machines in a static or constant speed situation have a 50/50 weight distribution (+ or - 5.0 percent) front-to-rear, we begin to calculate the guidelines of correct acceleration through a turn.
By the numbers, we want to transfer 10 to 20 percent of the weight rearwards, using the throttle. Technically, this is 0.1 to 0.2 G of acceleration. Simply put, it's the force generated by a smooth fifth-gear roll-on in the 4000 to 6000 rpm range on pretty much anything over 600cc.
That's not much acceleration -but it does the job."


That 0.1 to 0.2 G means a gain of speed of 2.2 to 3.3 mph per each second spent on the turn.
In terms of longitudinal traction of the rear patch that is 10% to 20% of the total weight (bike+rider) pushing rearward on the pavement (48 to 96 lbs in our previous example).

Consequently, your leaving speed will be dictated by the maximum traction and lean angle for those conditions and turn, while your entry speed and initial lean angle will be lower (more for a longer turn).

Coasting is advised by Keith as an OK approach, although not for the totality of the turn:

"When you get to the throttle determines where the bike is actually working. The earlier into a corner you get onto the gas the sooner you have the suspension in-range, weight transferred and so on. The later into a corner you get onto the gas, the more likely you are to be gas ''greedy"
for the exit."


Note that he refers to coasting as zero acceleration rather than deceleration (some minimum gas is supplied).
Wrongly, many riders extend the deceleration (by trail-braking or fully closed throttle) all the way to the apex of the turn, while over-taxing the front patch.
As I see it, they turn slower than they could, simply because, if describing a constant radius turn, apex means nothing and if they didn't slide at the entrance, they wouldn't from there to the apex.
This leads us to the conclusion that even if ground clearance is not a concern, it will always be better to be on the throttle to transfer that 10-20% of weight rearward.

Going along with what you are saying about people slowing in turns with no apex... If they were going to wash out the front, it would have happened at the moment they were at maximum cornering force early in the turn.

So at some speed for a given corner with a given CoF, there lies a point where you could make it if you were on the throttle, but would wash the front out if you were not. Now it seems to me this is going to be a very narrow range. So up until that point, you could actually get on the brakes, once you get to that point, you would need to be on the throttle, after that point, there's really nothing you can do. How small is that point though? Let's pretend that for given corner X, you could take it at 50mph and have some traction left over for braking with the front tire. But then if you tried to get on the brakes at 55mph you would wash out. If you tried to take it at 55mph on the throttle the whole way, you could take it. At what point after 55mph can we not make it at all? Is it 56mph? Or 65mph? How much "Extra" margin does being on the throttle give you is what I am asking. If it's only 1mph difference, then who gives a crap. If it's a 10-15mph difference, then it's far more critical...
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