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Corner Dissecting

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This has been covered in part, but don't recall if looking at the corner, and what are the priorities on how to sort out a line has been completely addressed. For example, the relationship of radius and camber. Lets say for the initial argument we aren't dealing with a substantial bump or surface issue. How does the radius effect the line used? How about camber? How do they relate?

 

Some of you might want to dust off Twist 1...

 

Best,

CF

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My head hurts.

 

My shortest answer is radius rules. Whatever camber changes there are in a corner, you need to understand the radius of it to know how best to handle the corner. You might have a decreasing radius on a turn's entry and decide to run it really tight. But, if the corner is a compound radius, double apex type turn, you can have other options. You could, in this case let it run in on a wider line and find that it sets you up perfectly for the second apex. Whereas, the tight entry runs you wide at the second apex. I can think of many other scenarios, that's one where radius rules.

 

Keith

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First, let me just say it is hugely awesome to have you on here twice in such a short amount of time, Keith.

 

Digressing. Would it be accurate to say that you take radius into account when choosing line, and merely adjust speed for camber, or would line be affected at least a little?

 

I think it's also true that entry speed is adjusted as well. You can really burn into a banked corner and friction will slow you a lot more, while being ginger in an off camber corner is recommended.

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How about uphill / downhill corners?

 

I'm wussy, and hate downhill turns - I have no feeling of how much grip I've got there (probably much more than I think).

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How about uphill / downhill corners?

 

I'm wussy, and hate downhill turns - I have no feeling of how much grip I've got there (probably much more than I think).

Could it be that you change your form on the downhill corners? Maybe if you have a good, relaxed grip, you tighten up, or if you press the bars a little, you don't in this situation? At the end of the straight on Chuckwalla, it's a small, ALMOST insignificant left, but I always made my way through it too slow, and was starving for speed on the way out of it. On my last trackday there, I realized I was staring my turn point down, so I broke way too hard because of the speed I thought I was at. I'm working on it, but it's become habit, so it'll take a little while. I'd bet there's something going on with form to change your feel for the grip.

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I am absolutely no expert of this in any definition of the word, but I have never had any problems trail braking around harpins down 10% declines all the way to the very edge of the tyres. The only difference for me between going up and going down is that I know that should I fall off, I will stop much quicker going up. And I need to start braking earlier going downhill to make the corner since I'm fighting gravity more instead of having some assistance from gravity. But my actual cornering speed, subjectively speaking, is the same. Probably because it's always slow.

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This is a video shot on my modified Daytona 900 down a road that average 7 % decline, although it goes up to around 10-11% in some spots. I were riding two-up and obviously a million miles off race pace, although you can hear the stand touch down here and there, probably a result of poor style.

 

 

lysebotn_bakken.jpg

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trail braking around harpins down 10% declines all the way to the very edge of the tyres.

 

Eirik

Uh, you say you corner slow. I guess it's relative.

The prospect of trail braking around harpins down 10% declines all the way to the very edge of the tyres

seems like more than the slow cornering you cite.

Gus

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I am absolutely no expert of this in any definition of the word, but I have never had any problems trail braking around harpins down 10% declines all the way to the very edge of the tyres. The only difference for me between going up and going down is that I know that should I fall off, I will stop much quicker going up. And I need to start braking earlier going downhill to make the corner since I'm fighting gravity more instead of having some assistance from gravity. But my actual cornering speed, subjectively speaking, is the same. Probably because it's always slow.

 

Not so sure stopping quicker is a plus. You know what the old saying is: It's not the falling part that hurts, it's the sudden stop at the end!

 

Anyhow, gravity is the advantage and the culprit in positive and negative camber situations. It pulls you down/in on banked ones and out on off-camber ones, simple. So you set up the turn to minimize the effect of off-camber and maximize the effect you get from banked...you can do that once you get a handle on the radius or radius changes. If you just go for minimizing or maximizing camber, without taking radius into account, you won't get as good a result. And radius will still rule.

 

Keith

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lysebotn_bakken.jpg

That's some ridiculously beautiful scenery!

 

That is insane, Eirik. Thanks for sharing that video. I've forwarded it to some friends. They'll love it.

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First of all lemme say Hi to Keith Code and second of all, it makes my joining of this forum feel... umm

 

Its like going to Disneyland on a regular day pass and meeting Walt Disney the man himself handling out ballons and handshakes :D

 

Back to Topic:

 

 

 

 

 

Eirik, I'll try to get a camera too and show you my area of the woods too, thanks for the nice video and pic !

 

As for said topic, Im still trying to digest both the question and answer ... ><"

 

 

 

 

 

 

 

 

 

 

 

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Not so sure stopping quicker is a plus. You know what the old saying is: It's not the falling part that hurts, it's the sudden stop at the end!

 

Keith

 

 

I was thinking more that it's better to stop in a few yards than to tumble off a cliff followed by a 200 yard free fall :D

 

But thank you for explaining further on the original topic!

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This has been covered in part, but don't recall if looking at the corner, and what are the priorities on how to sort out a line has been completely addressed. For example, the relationship of radius and camber. Lets say for the initial argument we aren't dealing with a substantial bump or surface issue. How does the radius effect the line used? How about camber? How do they relate?

 

Some of you might want to dust off Twist 1...

 

Best,

CF

 

Alright - a bit of homework! Took me a few days to get around to it, but I've brushed up on Twist 1 so I'll see how I go...

 

First up I was thinking that it seems like the answer kind of depends on the end product - that is whether you want to be coming out of the corner fast and with a really good drive, or just to be setting up for the next corner. Also it could depend on the strong points of both the bike and rider? If the rider (and bike) really like to carry alot of lean angle the line would be alot different than for someone who prefers to use the least amount of lean angle. In a corner with positive camber the ideal line would maximise the effect of the banking, whereas a corner with negative camber would be best taken with the least amount of changes (so no brake or throttle changes - to keep the bike as light as possible on it's wheels) and you'd want to spend the least amount of time in that corner as possible. The other thing to consider would be where your line takes you as the camber changes back to flat and what is happening at that point (as far as lean angle, speed etc.) - going from positive camber to flat will require an increase in lean angle to keep the same speed and turn radius, but a transition from negative camber to flat would mean you can use less lean angle for the same speed and turning radius. So... I was trying to think of a simple answer but the more I looked into it I realised that it's probably not as simple as the question itself... Unless I'm just over-thinking it which I'll admit seems to be a favourite past time of mine - I'm having fun at least! biggrin.gif

 

Radius rules - that makes sense. And I'm glad to have a simple answer on the camber-radius relationship. *Phew* tongue.gif

 

It's been pretty cool to see you here as well, Keith! biggrin.gif

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lysebotn_bakken.jpg

That's some ridiculously beautiful scenery!

 

That is insane, Eirik. Thanks for sharing that video. I've forwarded it to some friends. They'll love it.

Yeah, there's a really good reason why Lysefjorden (and Lysebotn) is considered one of Norway's most beautiful fiords.

Notice that point where the cliff kinda crests on the left side of the picture? - people go base jumping from that point every day in the summer.

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Eirik

 

Would you help me understand "trail braking" in this context?

 

Gus

 

You mean, in the "about to go flying off a cliff" context? :) :)

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Kjerag is the name of the cliff in the background, and there is a 1000 metre free fall from the top of the edge, going straight down to the sea. On top you have the Bolt. Google Bolten and Kjerag.

 

I don't think I'm qualified to help you understand trail braking in this context - or any other - Gus, only that I brake hard until the turning point then go off the brake in a fairly linear fashion until about where I get back on the throttle, although there is deemed to be a short moment of coasting in between the two.

 

 

 

 

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I brake hard until the turning point then go off the brake in a fairly linear fashion until about where I get back on the throttle, although there is deemed to be a short moment of coasting in between the two.

 

Eirik

Thanks.

Gus

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Mugget

 

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

Gus

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"I want that road! I need that road!" Jack Nicholson in a Few Good Road Racers. :rolleyes:

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Mugget

 

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

Gus

 

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.

 

Keith

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Keith

 

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.

 

Gus

 

css_camber_o_radius_rules.JPG

 

*o

n the way to the dogpark

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