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Old 10-26-2013, 01:47 PM   #59
beendog
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Joined: Oct 2013
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Quote:
Originally Posted by corndog67 View Post
You should get some professional instruction. There is some downright dangerous advise being given here, and some of it is absolutely wrong. I'm not going to go into detail about which of it is wrong, because someone will undoubtedly call me a Tea Party guy or a Liberal, and they will get extremely defensive and insulting about it. Again, professional instruction.

Take everything you read here with a grain of salt. Because some of it is worth less than a grain of salt.
Quote:
Originally Posted by joexr View Post
I have to agree with you on this. Instruction IN PERSON is a safer bet than TALK from someone who Heard IT from someone else or read it somewhere , but doesn't understand it or how to apply it.
Well, I just took level 1 and 2 of Lee Parks' total control class, but they didn't discuss traction gains or loss from braking and accelerating.

TBH, it still doesn't make sense to me as to why you would have more traction on the front with less weight, but less traction on the rear with less weight. I know for a fact when you brake, weight shifts to the front, and there is less traction at the rear. I know this because I can do a stoppie.

I also know that weight is part of what determines your traction, so if the weight of the bike doesn't change, and you have no traction on the rear tire(because it's in the air), your front tire *must* have way more traction than it does normally. And this is why you can brake so much harder with the front than the rear. The rear slides when you get hard on the rear brake, the front doesn't, WHY? because we have way more weight on the front from braking, thus more traction. As to why that concept doesn't apply in a corner? I don't know.

Now, I also understand that weight and brake/throttle are two separate things, which is why I posed the question of coasting through a turn. This is a concern when you would wash out the tires before scraping parts. If you are on a particularly slippery piece of wet road for example, in that case we ARE concerned with maximum TRACTION through the turn, regardless of available clearance.

In the case of accelerating through said turn, you have weight on each tire providing traction, while you have cornering force and torque consuming traction.

In the case of coasting through said turn, you have weight on each tire providing traction, while you have only cornering force consuming traction, no torque consuming the rear tire's traction. So we know for a fact the rear now has more traction available for cornering, but for the front, I don't know. We do have more weight on the front when coasting through, but we aren't braking, so cornering force is the only thing consuming traction.

Now, if the rear really does have SO MUCH MORE traction available than the front because of it's increased contact patch size, perhaps the extra traction being consumed by being on the throttle(to overcome wind resistance) is less than what is being gained from having more weight on the rear. Now it seems to me that that can't possibly be the case, I would surmise that we are closer to losing traction on the rear tire when on the throttle through a corner than we are when coasting through a corner.

The front tire equation is the one that I would be struggling with here. In neither case, coasting or on the throttle, does the front tire have anything but cornering force consuming available traction. Does having another 50-100lbs on the front tire consume more cornering force than what is provided by the added weight? Lee Parks' book says yes. But what this would mean is that the lighter your motorcycle, the higher G-force you could pull, which doesn't sound right to me. I don't think, even with the stickiest tires, that any weight motorcycle is going to be able to surpass ~1.1Gs on a skidpad.

We have cars with no downforce available that can pull .9G on a skidpad, and they weigh a ton or more. Granted they have larger contact patches, but if a 3000lb car can pull .9G without downforce, and a 350lb motorcycle can't do much better, then how does more weight = less traction in a corner? If that was true, wouldn't the 3000lb car(with no downforce) not be able to come close to a 350lb motorcycle's cornering ability? Given that we are talking about differences of 50lbs additional on the front tire when coasting vs on the throttle, how are we going to say that more weight = less traction in a corner when apparently we can add ~2700lbs of weight(car) and not lose much if any traction?
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