asinn0007

Hi Bullet, Yes, what you say makes sense. But what I see doesn't...With the pointy profile of Continental Sport Attack tires, the contact patch seems larger when leaned far over than when standing up. But the traction is stressed to the limit already with cornering loads. Also the compound is softer on the sides, which explains the sides being shredded. Upon closer examination, the rear tire's tread seems worn on the trailing side, as if it was shredded from trail braking rather than from driving out or power sliding. Makes sense, since I ride a Ninja 650R with 68 horsepower--not enough power to inadvertently shred tires--and I have on occasion been forced to brake while leaned over. To find what it feels like to brake at the limit, I practiced in dirt, at first, and then in a paved parking lot. My front chatters in the dirt, but doesn't seem to do that on asphalt. With the old tires, which were more slippery, the front used to chatter on asphalt too--almost as though I had ABS. Is this consistent with what I would find in level 3? Thanks. Ok, lets start at the beginging. Firstly, the contact path is at it's biggest when the bike is sat upright, (though, without confusing this, some tyres do have large sides too, though race tyres with very sharp profiles are more likely to be this rather than road tyres). You must remember that when you're sat on the bike, and when you're loading the bike with actions such as braking, turning, driving the bike, there is an amount of deflection in the tyre and that contact patch becomes larger. This is pne of the reasons its so important to set your tyre pressures correctly. The observation that you've noted on your tyres isn't likely to be at the limits of the bike or the tyre, its a consequence of the tyre being worked hard and the softer compound sides moving around and seperating from the carcass of the tyre. If you looked at any road tyre when it's been leaned on entusiastically should we say, you'd note this observation and its a sign of workloads put into the tyre and into the floor. Its nothing to be worried about. I doubt unless you were on very, very loose or very wet surfaces , that you would be power sliding a 68 horspower bike, and indeed from my own experience its actually quite difficult to do on even a litre bike on modern tyres in the dry, and they have upwards of 150bhp. You're observations of braking limits are very consistent with what you would see and feel on the brake rig. You should also be aware that its very easy to lock the front up attempting this and have a low side doing practising this, so please be extra cautious trying this on a bike without our lean bike outriggers which stops the bike from fallng over entirely. Coming together for you? Bullet Yes, thanks!

How is your street riding different from your track riding? Or is it the same?

Hi Cobie, Yes, I realize everyone perceives risk differently, but what does Keith mean when he says "70%"? I mean, when I say it hurts, it's not the same as when my girlfriend says something hurts. At hospitals, they have a scale indicating from 1 to 10 how much pain one is feeling. Does somebody have the equivalent for traction thresholds, a topic which is critical to a motorcyclist's health and happiness? If not, shouldn't we clarify this a little more precisely? Andy

Yes, thank you. It is wonderful when everything falls together so well. Still, without looking a gift horse in the mouth, I'd like to understand the "why" and the "how"--just for curiosity's sake. Also, just in case I make a boo-boo, I'd like to know what to do to recover.

Hi Bullet, Yes, what you say makes sense. But what I see doesn't...With the pointy profile of Continental Sport Attack tires, the contact patch seems larger when leaned far over than when standing up. But the traction is stressed to the limit already with cornering loads. Also the compound is softer on the sides, which explains the sides being shredded. Upon closer examination, the rear tire's tread seems worn on the trailing side, as if it was shredded from trail braking rather than from driving out or power sliding. Makes sense, since I ride a Ninja 650R with 68 horsepower--not enough power to inadvertently shred tires--and I have on occasion been forced to brake while leaned over. To find what it feels like to brake at the limit, I practiced in dirt, at first, and then in a paved parking lot. My front chatters in the dirt, but doesn't seem to do that on asphalt. With the old tires, which were more slippery, the front used to chatter on asphalt too--almost as though I had ABS. Is this consistent with what I would find in level 3? Thanks.

Thanks, Bullet. Standard Motorcycle Safety Foundation training suggests that 2 seconds interval is needed for stopping and reaction distance between moving vehicles, 4 seconds for road hazards. It occurred to me that this would be for a vehicle traveling in a straight line with 100% of tire traction available for braking. On my motorcycle while leaned over 40 degrees, for instance, there must be less traction for braking. Can someone please describe how best to determine braking limits? Regarding cornering, Keith wrote about "bands of traction", implying that different signals sent from the tires indicate different limits of traction have been reached. It also implies different dynamics come into play. There must be similar bands of traction in braking, each with its own telltale signals. Without prying any secrets from future lessons, to which I am looking forward, my question is, "If I ride with my tires just on the verge of squirming, with me sitting bolt upright without hanging off, what percentage of traction do I have available for braking?" How do I know when I've reached the limit for the traction available? Thanks.

How many G's of traction do Dunlop Qualifiers and comparable SuperSport Street tires have? 1.0 g's, 1.2 g's, or 1.4 g's? If my tires have 1.2 g's of available traction on the street, and I'm turning with 1.0 g of force, how fast will .2 g's of remaining traction slow me down? Of course, as I'm slowing, the turning force is reduced, allowing more traction to be used for braking, and so on. Thanks.

Everybody says it in one way or another, "Never ride at 100% on the street. Ride at 70% (or 80%) and save the rest for an unexpected contingency." Well, if hanging off the bike in corners and exiting with smoking power slides is 100% on the track, what then is 100% on the street? Andy by extension, what is 70% or 80%? Also, is it 70% of my bike's ability, mine, or whichever comes first? I took the first day's lesson and it has improved my riding a lot. I'm trying to practice my lessons, and I'm much more at ease and relaxed and I'm riding faster with less effort. On some technical, windy roads, today I felt the tires squirm a bit in a couple of corners, hmm. But the ContiSport Attacks are very predictable and I didn't feel threatened and stayed on the throttle. Getting off my bike at the end of the ride, I noticed that my chicken strips are largely gone, plus the outer edges of the tires have started to rub off or "shred." On the ride, it seemed as though I would be able to stop within sight distance, and I had the time to look to the turn-in point and the apex and still scan for road debris, etc. So it doesn't seem to me that I was riding too hard, but the shredded tire says otherwise. Where was I on the continuum of 0-100%? Where should the safety margin be located? Turning as hard as I was, do you think I would have been able to bring the bike to a progressive stop within my 4 second sight distance? Thanks for your help.

Thanks Cobie, and everyone else, too!

THANKS!

Thanks. Yes, I did replace the stock Bridgestone BT021 with a set of ContiSport Attacks. They are much stickier. Although after I had replaced the tires I read Keith Code's "A Twist of the Wrist II" wherein he says a lot of beginners would learn a lot from tires that aren't so sticky. I found the the Bridgestones were picky about pressure and operating temperature and can be sticky or slippery depending on conditions. I learned a lot about using the rear brake along with the throttle from those tires, stuff that I've almost forgotten with the Conti's. And I've had several exciting front and rear slides with those tires when cold or wet.

The Ninja 650R is a great bike to come back to motorcycling after 18 years off, but it is what it is. I agree the bike is not set up to be super-aggressive compared to the ZX-600's I rode at the track, but other than price, how can you tell from the specs? If I were buying a bike used, how would I tell if it's going to be a much faster ride than my current bike or just a pretender with a strong engine and lousy chassis and suspension?

I think you're right. Thank you. (#2) The transitions probably ARE too fast for this bike. (#3) But I can ride pretty darn quick without sliding the rear tires at all. If I misjudge a corner and slide one cheek off the seat, I seem to turn a lot quicker--sometimes unpredictably so. Come to think of it, when I plan to hang off, I do tend to push on the inside handlebar, almost as though I don't trust the bike to turn. So that's what is causing the tires to slide and have a bit of that rubber eraser look? Thanks for taking the time to answer my questions.

Don't worry. Everyone has to go through the same lesson plan regardless of experience. You are not competing with anybody, so there is no incentive to total your bike before you make it to SuperBike School.

I think I know that road. Isn't it near the top of the Big Island? It's high enough to have sudden snow storms in the afternoons or evenings. Everybody drives like a race car driver up there. I couldn't keep up with some commuters who were running home across the peak through a blinding snow storm with 3 feet of visibility down some twisties marked 20-25 mph at 45-55 mph. What a ride! Love those roads.

You're riding the 1000 on race tires, and it doesn't seem as though you're riding hard enough to get those tires hot enough to stick. To get the 1000 to go faster than the 636, you need to drive harder out of the corners and brake harder going in without disrupting the stability of the bike. Your turning speed will be slower on the heavier bike, all else being equal.

I don't hang off on the street unless I've screwed up. I think it's the rebound dampening.

Correction, I can adjust rear preload, which is in stock setting for my 180lb weight. A riding buddy said my preload on the front was too high and wanted slide my forks up or cut a coil out of the front springs, but neither sounded kosher to me. Should I adjust the rear preload up a click? That would put more weight on the front. Is that desirable? Thank you.

I ride a Ninja 650R, and unless I'm mistaken, there are no suspension adjustments. What are issues that I'm looking to resolve?

1) Sometimes, when I get a corner right and roll on the gas fairly aggressively, the rear digs and then the suspension compresses from centrifugal force. Is this an okay thing to do? 2) If there are fast chicanes, the bike can seem to bounce from extreme left leaning to extreme right leaning. Is this safe? 3) If I need more cornering force, I hang off, and eventhough the turn radius is reduced, the tire starts squirming or sliding a bit immediately. I assume this is because the thrust center is misaligned from the center of gravity. Is this desirable for street riding? Why or why not? Thanks.

1) Sometimes, when I get a corner right and roll on the gas fairly aggressively, the rear digs and then the suspension compresses from centrifugal force. Is this an okay thing to do? 2) If there are fast chicanes, the bike can seem to bounce from extreme left leaning to extreme right leaning. Is this safe? 3) If I need more cornering force, I hang off, and eventhough the turn radius is reduced, the tire starts squirming or sliding a bit immediately. I assume this is because the thrust center is misaligned from the center of gravity. Is this desirable for street riding? Why or why not? Thanks.