Balistic

That and it takes time for the tire lube to dry and the tire can slip on the wheel from hard braking changing the balance

For the most part your tires look great, I do take exception to the rest tire pressure, I lwouldnt recommend less than 29 in the rear. I see you are checking pressure rise and even though you are still in range 25 is a too low. The US GPs started going that way when the N-tech construction was introduced and are now below that at 21 cold. You can expect to see the surface getting roughed up like that. Thanks, Will

at the track there is a limit to what is considered acceptable. it is my opinion that once a tire is balanced it doesn't matter how much it took. On a "race tire" when your spending a couple thousand dollars on mag wheels and tie bolts ect. you don't want to go and slap a bunch of weight on to balance a tire. The real facts are a tire that takes a lot of weight may go out of balace durring it's life more than a tire that took little weight. Most tires do spin on the wheels when ridden hard so it becomes a mute point as when it moves the balance goes off. if it's not hopping it's not a problem.

I agree with everything Sean has posted but agreement on this very limited. it's hard to find an AMA tuner that wants to raise the rear of a bike? Seems most like to raise the front to get the newer bikes to handle for the current crop of trail braking riders. IMHO it always comes down to the riders style which way you will go, a rider who is early to the gas after turning will like the rear up and a rider who runs it into the apex with the brakes on will like the front high. Will

The only thing I could add is that bikes with similar front and rear tires steer and turn very well. back in the day of 16" tires we used to put 120 fronts and 130 rears on Ninja 250s and they worked much better than the 100/120s they came with. The other example would be the HDs with 16" front wide (150) tires, like a wide glide. I think the rear is slightly bigger but a 15" wheel making it nearly the same size. They handle great! very light steering and neutral in the corner. Yea I know we are talking half the lean angle but it's still true.

I have just recently made an interesting discovery that may or may not apply to other brands. I have had one bike that has not been running right and I had been chasing it for two months. I had changed the fuel pump, coils, injectors, and finally the wiring harness. at every point it seemed to be fixed only to start running poorly again with a slight miss just off idle and then falling short on power above 10,000 rpm. after talking with the tech line at Kawasaki and checking all the sensors at the ECU I changed the spark plugs and bam it was fixed? It appears the ECU is capable of interpreting resistance in the coil and going into a limp mode to protect the catalytic converter. On the Kawasaki at least there is no way to monitor the ECU to see the decisions it is making? At any rate my advice on modern EFI bikes is to use the recommended plug and replace it when recommended.

I have stayed out of this Frey but at this point I feel compelled to post. I got a nickname when I fresh out boot camp that I earned with my ability to change my mode of operation in the blink of eye to respond to a situation. Many already know this but it is my screen name Balistic. 0 to 10 on the attitude scale with nothing between, it has nothing to do with any other kind of speed. As for Cobie's, it would be a great injustice to all the elder staff old enough to have watched any of the Mr. Magoo cartoons growing up to pass on the oblivious and award Cobie the nickname of MAGOO with the Os done up as eyes.

The measure I always use is lap time. How to set the gearing up to get around the track the fastest. Things I don't want, 1. To need to shift coming out of a corner leaned over 2. Not to be in the power when standing the bike up at the end of a corner 3. Not to be on the rev-limiter anywhere on the track. I raced at Streets of Willow and Big Willow with the same gearing on my ZX9 and my 636? I didn't run into any of the situations above. The 9 was five teeth lower than stock, the 636 was three, and more recently Lonnie's 600 was five teeth lower than stock.

I am late on this thread and much has been covered, there is one thing I didn't see though. How the tire makes heat was covered but not how it covects that heat out? I would start by saying yes to lower tire pressure making more heat through flextion. There is another side to that sword in that the tire from convecting heat though the contact patch to the road. Basically you have the heat being generated at the edges of the contact patch by flex and being convected away in the contact patch. It works like a radiator on a car, by lowering pressure you are putting a bigger radiator on the tire too. You don't always get more heat by lowering tire pressure. Pressure rise is a very good way to manage tire temp, 6 to 8 psi from cold to hot will put the tire in the 160-200 range. less than 6 lower pressure, more than 8 raise it.

That is one of the most loaded questions I have seen in a while. I can only speak from my own experience on the school bikes and a few times having ridden a fully stock bike at speed. The suspension, power, tires are the limiting factors on a stock bike! I took a stock 05 out at Mid-ohio to do some shots for a TV crew, I always take the opportunity to "make something happen" to see what it looks like on film. I ended up doing a 1:39 and the supersport cutoff that year was a 1:37, pole was a high 1:29 I think. On a good 600 I might have done 1:33? Ohio is very twisty track with connected turns so the power deficit wouldn't show like say Miller where I think running the AMA short course you would be lucky to keep it under 20 seconds differential. Another example would be the Code R.A.C.E. schools where several instructors have done 1:22 - 1:23s on our bikes, some with all the street stuff on 1:15.9 track record. It depends a lot on the length and configuration of the track, 1 second a 1.7 mile track is a lot more than 1 second at a 4 mile track. Will

The interesting thing about tire pressure is what it does to the tire. You want the tire to flex so it will generate heat and get to a temp in the 180 to 200 range. Too much flex and too much heat, you also may have a loss of feel. With the exception of the new low pressure tires (18 to 23 psi) there is a balancing between generating heat and disipating heat. When you lower the pressure you expand the contact patch and that is how the tire convects heat out, so while you are getting more flex and heat by lowering the pressure you are also increasing the convection out of the tire, sometimes to a net loss of temp in the tire. The most important thing is that you get the tire up to temp, at 38 psi it is unlikely you can get a rear tire up to temp.

The base track pressure for most all tires is 31 front and 29 rear. The recommended pressures are for max load and speed the tire is rated for and have nothing at all to do with traction. A radial tire at 38 psi on a sport bike single up might as well be a bias ply, it will not flex enough to realize any gain from the construction.

Everyone has thier own "hot set-up" i set my trailer up to do anything, so I don't want to obstruct the floor or the walls. i use http://www.condor-lift.com/product.asp?ItemID=1001, there is no better stand and I don't have to bolt them down to use them. /the other thing i like is to put E-track on the wall and floor so i can D-ring at any point. I like 12" and 48" center on the walls and went across from wall to wall 4' center.

What I would really like to do is do it on the telemetry bike. I haven't got my head around pushing a bike with $45,000 of electronics on it though.

[quote name='acebobby' date='Oct 4 2008, 11:10 PM' post='7353' I have a question though, in a chicane type corner, what would be the correct method of turning say you are all the way over to the left and want to flick right, should you stay on the gas left to right, back it of a little or close completely and crack open and roll on again when you have turned right? Thanks B quote] That is an open ended question with sooooooo many answers. Take Barber for example, the back straight chicane. It is about a 100 mph left to right flick. I will dip the gas to turn the left and get right back in it and for the left to right I will dip to about half throttle. Streets of willow turn 11 to 12 (skid pad) I will come into it with the rear at the limit ( 3/4 throttle) and just before the right to left flick goose it to break the rear loose and as I drop the throttle use the front brake a tiny amount to get the bike to counter steer itself as the rear hooks up and tries to high side the bike. I would call this passive steering, I don't have to "steer the bike with the bars until it is almost upright. That looks a lot scarier in writing! Just two examples, the ends of the spectrum in answers to your question. Will

PS - The title under your photo at left still says "Riding Coach". Are you going to change it to "Mechanic"? The webmaster thinks it funny to change my stuff?

At the risk of exposing my inner self (SQUID) the first time I found out about this was when lane splitting and changing from splitting the one two lane to the two three lane, warm tires, sunlight, ect. I don't recommend going out and "trying" to do this. I snuck up on it with my Daytona special RD400 some months before it departed this place in a big ball, a wheelie gone very wrong. at this point I have figured out how to keep the tires on the ground, if I do it now it is for demonstration or a mistake in turning too fast for the bike I am on. Will

Another thing worth thinking about is when you flick the bike back up, say a set of esses or what you call the knee to knee drill! e.g. if you flick the bike from left to right to 45 degrees does it require more effort in the upward motion (against gravity) than moving in the downward motion (with gravity)? Does the bike go downwards faster than upwards, I don't know which way is faster but I can say I have turned bikes from knee to knee fast enough that the wheels leave the ground. Driving the front wheel under the bike fast enough to bottom the forks and compress the rear, with both rebounding and the increase in radius from the side of the tire to the center effectively jumping the bike right off the ground. I don't think you can turn it from straight up and down to lean faster than gravity will pull it down, but clearly gravity can defeated coming from leaned to straight up.

QUOTE I am entering a discussion, not an arguement! If it takes 1 tenth of a secnd for an object to fall 1 metre, if gravity pulls the bike down, wouldn't it be possible to steer your bike to the desired lean angle in less than 0.1 of a second, can anyone steer this fast? Say from upright to 45 degrees probably a distance of less than half a metre. Take a sportsbike, at 20 mph it is easy to steer to 45 degrees but what about when you go faster say 60 mph, does it require more effort to turn? what kind of effort does it need? is it push the bars harder? or push the bars faster? or both? You know, I think you might really be onto something here, Bobby. Not only about the time it takes to lean the bike, but, also the difference at different road speeds. This is what I was thinking about today while communing with a 600RR and meditating on Will's leverage angles. The amount of force and leverage it takes to turn the front wheel increases greatly with speed. Partly due to the increase in resistance of gyroscopic forces, and, I think maybe partly due to resistance of the caster or trailing geometry. I wonder if resistance due to trailing geometry also increases with speed. -------------------- There is no spoon! I try to use my riding as an example but on my best day I can turn a bike about as fast as anyone, that would be 1 to 2 tenths from vertical to full lean. I didn't know the exact number for gravity but it seems to be very close to my experience.

Racer, WOW! 85% I wouldn't have guessed more than 50% and I wouldn't have bet on that. Acebobby, I believe when racer was talking about wheel base he meant wheel track. At least that's how I read it. That is why they call a bike a "single track vehicle".

I hate using an auto or aircraft as a reference for what is going with a motorcycle. I live by Newton's laws. I know there is a point in there somewhere and it seems to me what you are saying is it's not gravity but what it creates that is responsible for the bike leaning? I said earlier "knock the front end out from under the bike" and what I am saying is by turning the front wheel away from the direction of travel the force is transmitted through the steering head and at the same time the mass is not turning yet but is being made to lean by the twist induced to the steering head and gravity pulling down on it as the front wheel isn't under it in a supporting way. A couple of small points; the forks have sag and can extend away from the steering head as the wheel drives in the new (steered) direction, and do. The rear of the bike counter steers too, goes off track in the direction of the steering input. This is caused as the mass rotates around the center of mass to a degree. The tires are not fulcrum; it is higher and can be seen in video. I think this is where we disagree. Will

Hey Racer A couple of things first, I said "I" am a layman, I am also a red neck, white bread, cracker. I take no insult in any of those. And yes I do like talking about this stuff though you can and did go too far outside my understanding of the "math", and no a dictionary would not be enough to follow you. I am not a coach, I am a mechanic who knows how to ride and my expertice is in the practical application not the theory. I was tought to ride, I am a natual mechanic and fabricator though. When I said I love this topic, I do, in spite of the percived insult to you. I really did need to go and operate some equipment. Will

Well all I have to say about that is I do have a conceptual knowledge about how a bike works and can explain it without subterfuge and misdirection in simple terms ( as I am a Layman) without need to go into a pedantic ramble that only confuses the issue with esoteric terms. That being said, Physics is a great piece of the puzzle but it is only one part. it is not the end all and it does not discount the effect of geometry on a single track vehicle. The physics of it is in fact a way to understand " WHY" geometry works. So for now I will still have to rely on what is demonstrable as I find the "scientific" explanation induces drowsiness and I have machinery to operate.

The only problem with the idea is you would have to be holding the bike in the air and dropping it to get the idea of how fast gravity would move the bike. If you are assigning the rotation all to steering the front wheel then what is keeping the wheel on the ground as the center of mass is the fulcrum of rotation? IMO knocking the front wheel out from under the bike is only allowing gravity to do its work and suck the bike down. It's when the steering input is released that centrifugal force is generated to balance out the gravity at the new lean angle, or you drive the bike right into the ground with the steering.

I love this topic. One thing that is not debatable is that the physics is real, the question then remains does it have more of an effect than the geometry or is it a secondary force having little actual effect? I pulled this out of the article because it is the exact point I depart the physics; "This moment tends to tilt the motorcycle in the opposite direction from the steering motion; for this reason, to curve into a direction during fast driving, the rider exerts a quick rotation of the handlebars in the opposite direction. The higher the velocity of handlebar rotation W, the higher will be the moment that tends to incline the motorcycle into the opposite direction." When you turn the front tire it is the tire working against the ground driving in a new direction that causes the bike to lean, acting through the steering head and gravity pulling the now out of balance bike to the ground. What proof can I offer? How about a race bike exiting a corner with the front wheel an inch off the ground and the front wheel turned having little effect? Being a wheelie expert I have long played with front wheel gyroscopic effect to turn the bike with the front wheel in the air. I can say with a high degree of certainty that if the tire is not touching the ground counter steering has little effect, or the exact and total effect of precession. With the tire on the ground the gyroscopic effects are completely secondary and never even catch up to the effect the tire creates in the lean angle of the bike. Another point is if you take the gyroscopic effect as the end all for turning the bike how do you reconcile the fact that once the bike leans from the steering input the front wheel driven by trail will turn into the corner past center to balance the bike on the radius generating an even greater precessional force that should if you assume it leaned it in the first place immediately stand the bike up! DOOOOHHHHHH. Will Eikenberry