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Corner Dissecting

Cobie Fair

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Thank you


I wonder about going back to the "radius rules" comment? I scratched my head at that*, thinking back to Twist 1, where I read:


Not sure what question i have here, but I thought I'd bring it up to understand the thread that connects the two statements.







n the way to the dogpark


Isn't it amazing what happens over a period of 27 years, 12 million track miles and 150,000 students...you can actually discover things :-)


The statement in the book isn't absolutely right or absolutely wrong. It states that, "the radius of a turn is OFTEN second..." Not always. I was leaving myself some room on that statement just in case I discovered more.


At the time of writing, I wasn't thinking that much about radius because, and this was a big error, I couldn't imagine that someone wouldn't have already figured that out. Big error. All this time later, I know that isn't true, riders don't always see what I or you see.


The big leap forward is that we now know exactly why they don't see it. The drills on Level II are intended to help sort that out and most often they do.





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  • 1 month later...

Does this accord with your comments?

positive camber to flat
results in

  • ==> effectively a DR corner
  • decreased effective LAGC

negative camber to flat

  • ==> effectively an IR corner
  • increased effective LAGC


Exactly. Once you sort out the actual radius then you have the effective radius to coordinate with it.

Positive to flat in a constant radius corner you try to neutralize the decreasing radius effect by adjusting your line to create an increasing radius line. Turn in a little later. Choose a slightly later apex. BTW, the same would apply for trailing the brakes in as it would for getting out of them while you were more upright as far as line goes.


But don't forget, unless the rider was at the limits of tire adhesion, there are more options. He could also go in and stay right on the curbing a little longer, not using a "touch and go " apex, and still get a brilliant drive off the corner. That's just one variation.



I'm reading up on the Twist-1 and came upon the camber-change discussions in chapter 3, and I realize that I'm thick-sculled enough to not being able to figure out for myself, how to design the "right" line for the real-world turns I'm seeing.


Most of the turns with camber that I've seen actually changes camber twice: they go from flat to positive and then back again to flat from start/mid/end of the turn.

The old start/end-turn of Anderstorp is a good example of such a turn:The turn is almost a perfect right-hand semi-circle with a diameter of a whopping 388ft (118m). The track is 10meters wide (33ft), with maybe 2ft of height difference from the inside to the outside of the track mid-turn - so there are literally thousands of possible lines through this turn.

The turn leads onto a straight, so I want the best possible drive out of this turn (and not waste time in the turn itself).


In the first half of the turn, the camber will be increasing, so this will work as an IR turn. This should allow me to either be able to either keep a CR turn with added throttle, or starting out wide and making the turn tighter (DR).


In the second half, the turn becomes DR, so I could do what Keith writes above: adjust line to make a IR line and get more upright sooner to reduce the LAGC problem. Adding the "pick-up" would probably be a good idea. (I've had a couple of scary slides out of such camber-->flat corners with suddenly makes sense to me).


But I'm at a loss of how to put the two halves together into a single line.


So far I've been using a turn point maybe 1:3rd into the turn, and then have an apex about 3:4th through the turn (and staying at the curb for some time). However, I feel that I'm wasting a lot of time in these type of turns and I'm not getting the drive(s) out that I'm expecting.


Thanks, Kai

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