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John Culbert

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  • Have you attended a California Superbike School school?
    Not yet! (Can you come to Kershaw, SC?)

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  1. Somebody said, "Buell"? Yuk. Well, at any rate, you should thank me; I paid too much money for the s-l-o-w S-2T, which promptly warped its front rotor, got recalled twice, wouldn't go and had less ground clearance than I wanted. I sold it just in time to miss the 3rd recall. I mistakenly thought it would hold its value. Umm. That money went to Buell so they could build better ones - they say. I'm still not impressed all that much. "Different" is not a synonym for "better". I have 21,000 miles on an '01 ZX-6R, which works for me, for the simple reason that I'm not fast enough to expose its weaknesses. You fast guys know that workarounds are necessary for every bikes woes. We slower guys can actually see you do this on the track in competition - it's part of the appeal. A guy like Cobie can outrun most people with a littler bike. I've seen Jason Pridmore do it with an SV650 - that is, pass R1's, CBRs, you name it. My next bike will be small, like a 400SM. You want to talk handling - let's talk about hopping curbs at Daytona on Main Street, at Weirs Beach, at Sturgis, and if you drop the bike, well, pick it up and let's go!
  2. Just remember - you weigh half what the bike does. Of course body position matters for all direction changes. My major point is that the rigidity of the elastic part of the man/machine pair - you, the rider - is drastically affected by how you are seated and how you weight pegs and bars. "First motion" of any bike component, around any axis, depends on how much mass resists accelerative force via inertia. This has immediate and gross effects on handling. I don't know where to find the article, but Kevin Cameron wrote a few pages on this.
  3. I wish I could get anyone - anyone - to realize how important that is. So many people think they are driving a damned car with handlebars... Grr!
  4. You know, this first post doesn't have to be a troll. Most of the folks I know have a story about some fellow who goes to a dealer and buys some rocket. Shucks, I helped a fellow load his new Softail Deuce on his truck - and that was HIS first bike - for thirty grand! He fell over idling around on the grass in his front yard. Bummer. Anyway. It only takes one trip to a track to find out that just a surely as $15K and 50 miles doesn't make you a Hell's Angel, a check from your credit union can't make you Mat Mladin or Eric Bostrum or... (name awesome fast guy here). In fact, I have had the immense satisfaction of seeing a loud Hayabusa fan shut up after taking his rocket to Loudon, for lessons with Eric Wood. See, he got passed by guys on EX500 Kawasakis... ...just as the man on a ZX-10, R1 or GSXR will get passed by any of Keith's staff - on 600s. If you really don't know about throttle control, you will hurt yourself on the track with an opn-class bike, It happens all the time. I've already proven to myself how slow I am. I have nothing left to prove, and everything yet to learn. I hope you can learn and attend one of these classes first, using a school bike.
  5. Rifleman, the largest quantity of water found in motor oil comes from combustion by-products, as do the acids. I'd really like to see a citation of a manufacturer or dealer voiding a warranty for using synthetic oil; this is only part of the story. See, no oil which meets SAE standards may be the basis for a warranty denial; that's the law. However, if you are known to have taken the bike to a racetrack, that is grounds for such denial. Also, mixing ester- and non- ester-based oils can be cause for denial of warranty service, but this denial can be defeated if you can show that no warnings were posted, flushing was done and the bike saw only street service. Sport Rider did a nice write-up recently about oils, although they couldn't be complete.
  6. Cobie, I'm looking at my schedule, which is changing drastically sometime in the next three months. Jennings and Barber are both good bets. I hope to see you somewhere this year!
  7. I can explain that, if you have a minute and some visualization skills. Place any object on the table. Exert a sideways force on it, and you'll discover that it really likes to stay where it is. When motion first occurs, it is easier to keep the object moving than it was to start it moving. This is not inertia at work - it is an example of the difference between two coefficients well-known to engineers: the coefficient of static friction and the coefficient of sliding friction. On a minute level, any object in contact with another has a large number of surface contact points which intrude upon the other surface. The first phenomenon here is exactly like the action of a dirt-bike tire; tread blocks intrude into dirt to get grip. The tire's contact point, street and dirt tires alike, are intentionally built to offer the most friction - which is called traction when applied to motor vehicle propulsion. A street tire works exactly backwards from the dirt tire. It has to let the road surface intrude upon it by conforming closely to pavement texture. So, pause for a moment, and think about it. The tire's contact patch is completely stopped, isn't it, unless you are sliding the tire? No. The tire is rubber, and it does not lock to the road like gear teeth. In rotating against forces of propulsion and braking, the tire "crawls" quite a bit. Perhaps you've heard about Daytona cases where the back wheel of a Superbike is actually spinning faster than the bike is going? This is simply a matter of tread elasticity, where, in order to exert a force, rubber must be stretched. At the contact patch, this means that as a point on the tire first touches the road, it has no load on it, and that as it rotates under and back, a point on the contact patch will assume and release load proportional to the rubber's elasticity. But you aren't asking about that, directly. You want to know if a tire must slide for maximum traction. On motorcycles, that answer is yes. Go back to the example of the difference between static and sliding coefficients of friction. If we were just trying to keep something from starting to slide, we would build a system that would bond very tightly to whatever it sat on. Glue is a good example of a substance that intrudes upon a surface in order to maximize the force needed to dislodge an object. But we have to roll. We can't just put the tire contact patch in one place and leave it. We have to accelerate in all directions, and deal with weight transfer. So tires are built so that they first intrude upon the texture of the road surface, and then intentionally yield by allowing the road surface to abrade them. This costs a great deal of energy - one of the reasons you need less braking than you might think just in cornering - and energy is the product of force and time. The force appears, after conversion by the motorcycle chassis, as acceleration. The energy which goes into heating the tire comes from the engine, the source of all your velocity. The tire's ablation converts kinetic energy into heat, exactly like your brake pads do, and disperses heat by shedding chunks of rubber, conduction to other parts of the tire/wheel, and convection to passing air. You have probably seen the results of tire ablation. Those tatters hanging off the tire are evidence that this occurs even when gross (spectacular) sliding is not going on. When the tire gets hot, the rubber becomes self-lubricating; it cannot absorb any more (coincident) energy of ablation without liquefying. Look back for a moment to where I mentioned "tread elasticity"; when a tire is actually sliding, all of the contact patch is loaded to its elastic limit, and is transferring the kinetic energy of your motion through several conversions into heat and force. Does this help? There is a lot more to this...
  8. One more thing you can get from CSS: Most street riders don't quite know what safety gear to get, or what is available. Although the magazine guys note that there are more jackets out there from Joe Rocket and the like than there used to be, the high cost and limited inventory of some outlets makes finding the right suit, boots, and gloves difficult. In my case, it's a long ride or several shipping transactions between me and any new bit of apparel I might want. If you go to CSS, you can find out firsthand what comfort and protection levels are available in apparel, and speak to assorted folk - the "poster children" of diversity! - about their expensive Dainese or cheaper AGV gear. Yes, it's important to have good gear on the street - and most "motor clothing" is totally useless. The good stuff is expensive, but it will last for twenty years or a hundred yards, if you get my drift, and will pay for itself "on contact".
  9. It seems that there are enough races completed that we should be able to watch what the winners do. With different riders succeeding despite wildly different backgrounds... What does Metzger do? Schwantz? Bostrom? And why would it be any different than, say, 600 Supersport? At VIR last year, I watched Tommy Hayden run off and leave everybody, while hanging the back end out about six inches every lap. It seems to work fine so long as the tire doesn't go away. When you say, "fast stuff", you mean turns in which you don't have to slow a lot, right? Because, at VIR, the turn I was watching seemed to demand about 60MPH less speed than on the uphill straight.
  10. I hope y'all get to go to Kershaw (Carolina Motorsports Park). I've only been there four times, and once to Talladega Gran Prix (not the NASCAR track, of course), but Kershaw is lots of fun. I think it's easier to get to than VIR, but VIR has the AMA blessing...
  11. This is a totally unfair question! As a part-time rider of track days and an occasional school participant ($$ and location, doncha know), I think most of you guys are missing something: the bulk of pro roadracers are really nice guys - on Sunday after the race. (I know enough not to be a bothersome fan between rounds.) I think this comes from the fact that the track is the enemy, as much or more-so than any competitor. There are exceptions, of course. But I have met Anthony Gobert, Miguel DuHamel, Aaron Yates, Rich Oliver, Chuck Sorenson, Jason Pridmore, Dean Mizdal, Eric Bostrom and Doug Chandler when they weren't signing autographs, and their easy manner and grace in speaking to a nobody is quite wonderful. It's one of the things which makes the sport superior to NASCAR or various games involving ballplay. Yes, if you put Roberts, Sr on the track he'd have to win.
  12. Keith, Your recent article on using the No BS bike to explore what attitude changes occur as a result of throttle control is very significant. I have read a great deal about damping curves, bending forces, modula of elasticity, etc., but this bike - along with your gritted teeth - will show people things they can use. It'll show you why Kaz Yoshima's dinky little suspension-travel indicators work, and will probably let you pick tire sizes and profiles absent superstition on the subject - but there is something else to be noticed in the use of the No BS platform: body position has real effect. Over the years, there has been what I consider unnecessary friction between body-steering and bar-steering fans. It's clear that both principles apply to riding. Well, where's the confusion? Those I have spoken to are at a loss when I mention a common engineering term: mass coupling. See, if a mass is not rigidly attached in a system, then, when it is accelerated, the center of gravity of that system will move proportional to the acceleration; the direction the center of gravity moves will also not be constant. The rider is certainly elastic; further, (s)he intentionally moves around on the bike. You know very well that on the dragstrip, 60-foot times are critical, and that truly tiny adjustments in the rider's routine will affect the bike drastically. I submit that the same is true in roadracing. In judo, the position of the hands and feet are critical to the outcome prior to any force being applied to one's opponent. On the track, your position on the pavement presents a limited number of options for forward progress. It is only logical that your position on the bike produces small changes which have large consequences for upcoming control input and the resulting action of the bike. The No BS will show all of that, and lay argument aside for reason! Excellent! By the way - you won't get me to take my hands off the real bars!
  13. In 2000 and in 2002, I participated in Jason Pridmore's STAR school as it came to Kershaw's Carolina Motorsports Park. Boy, what an eye-opener. I found out that I had been riding with bad habits for more than twenty years. I promise you that you'll talk about one of these schools for years, should you go, for one overwhelming reason: you get to learn what's right, and that frees you from fear, even as a casual street rider. In one lap, I was sad, mad, glad, thrilled, exuberant, humbled, pleased and relieved that I had made one of the best choices in motorcycling. Kershaw's a wonderful track, but STAR is not coming to it because it's tough for the staffers to get to. Keith - or should I say, Mr. Code - I hope you'll get closer than VIR to the Aiken,SC area. I always find it a pleasure to speak to and work with somebody who knows what's what!
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