edit up front before posting. Hi Ted, I wrote the below with you in mind to make it easy for me, and to have something to relate to while writing. Though it's written as directed to you as criticism and arguments of what you expressed, ... its intent is to offer a general idea about how we see stuff and not to throw slings and arrows at you. We've read each other enough on here, that I think you can and will take it as not pointed directly at you. maybe a ricochet might get ya, but just let it glance off. ...
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edit up front again, I could read through it re-writing it so it's in general or post it in a new thread and I probably should do that. But the football game went too long last night and with only one coffee yet, it just seems like too much work right now.
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Ted I think your totally confused about roll centers and bicycling. Moving roll centers has nothing at all to do with weather or not a kart will bicycle. It's been pointed out time and time again on here, especially by Todd, that steering input in a well setup kart is minimal and basically insignificant. So often it is reported on here by drivers, about how they do not even turn the steering wheel. You point us to writers of books about suspended cars, those cars have one side exactly the same as the other, we do not race stuff like that. ...
I don't understand or have a clue how to determine the roll center and instant centers on a kart. My reference, and I think everyone else's reference on here, without being able to define the roll center is a gut feeling, from experience or as in my case and probably others a picture in your mind you can look at and get an idea of how stuff works. Beyond that all racers can do is either remember general things they do to change how things work out on the track, which is called experience; or write things down and gain a library of what to pick to do, to change how things work out on the track.
Beyond that neither you, nor I, nor anyone else can define where the roll center or instant center is located. You can't do that because by definition the location of the roll center, no matter how many stick drawings you put on, is defined by actual suspended chassis operation. You can't define the suspended chassis on a kart and that makes it impossible for you to define the karts roll center. I express often on here about how I look at things, in terms of how what is done works with a moving picture I have in my mind. I most always end with how I'm not necessairly right, because I realize all of what I see is only that, a mental picture I use for reference. When you tell us your incomplete stick drawings are about the way it is, IMHO your not telling us about the way it is; your only showing us a reference you use to understand something you cannot define.
If you can in practice find your karts roll center, please give us the process you use to do it. Please include all measurement points and forces involved which dictate the location of the roll center. ya know what I think my thoughts are telling me? maybe all this stuff is really just gut feeling and seat of the pants experience. Is my gut feeling or seat of the pants experience any better then anyone else's? Absolutely not and that's probably why I always have so many questions. I just don't know for sure, ever. ...
paul
edit at the back: To bring this bull back to the subject, I think the amount of split used is because that the amount of split which seems to work best for the situation. There usually is some and the amount is what works or is there.