Hotfoot

Here is a page with good info from Snell: http://www.smf.org/helmetfaq#aDroppedHelmet Something I read recently said you should not hang your helmet on a side mirror or handlebar, because it puts pressure on the inside and can crush parts of the foam lining. I had never thought of that.

Right or wrong, one of the quickest ways to lose credibility as a speaker or a writer is poor grammar. It doesn't necessarily equate to a lack of knowledge about your subject matter but it makes one think "if you don't care enough to put the effort into what you are saying, why should I take you seriously?" And this comes from someone who always struggled with grammar. The English language is a linguistic assault on logic. Ain't that the truth! :) Now that you mention it, this forum is better in that area than any other riding forum, in my opinion. I look at other forums sometimes and the grammar and spelling errors are mind-boggling. Along those lines, anyone know how to force Google to eliminate any "Yahoo Answers" results from any and all search engine queries, forever and ever?

Here's some food for thought: 1. Can you calculate your roll-off without locating your turn point? 2. Can you know how MUCH or how QUICKLY to turn the bike if you haven't located your chosen apex? 3. Are you willing to roll on the gas if you can't see where you want to go? I don't know how you could list vision as a discrete step - because there is no point where vision is no longer a requirement; as Keith says in the book, your vision should provide a flow of information. A choppy flow of visual info will result in choppy riding. I appreciate that you are thinking things through, but I'm curious - why are you trying to make a mantra? What are you trying to accomplish by doing so?

Hee Hee, I love this answer. I think part of the idea of practicing the drills at the school is to get you to an understanding so you don't HAVE to talk to yourself as you ride around. That way your attention is on monitoring the flow of visual data and info from the bike about traction, etc., not on thinking about what to do.

WOW. That is quite a turn, and you weren't kidding about it being light bulb shaped! Maybe see if you can find a place where you can get on a constant circle, set your speed and then try doing a slight, gentle roll-on, then gentle decrease of throttle, with your arms VERY relaxed on the bars, and observe how your line changes. Too much will make you go wider, but not enough will end up slowing you down and making your arc tighten. Cornering and wind forces will have the effect of slowing the bike, so holding the throttle FLAT with no roll-on at all will end up with the bike slowing down. So, if you are smooth with it, you should be able to use your throttle throughout that whole long turn to widen or tighten your line as desired. If, at the end, you find that you are a little wider than you want, hook-turn would be very useful - have you been to CSS and seen that technique? It is a challenge in a long turn to use enough roll-on to stabilize the bike and hold your line but not so much that you end up with TOO much accumulated speed at the end. If you feel like you are having to steer the bike back out, though, I'd try adding a bit of throttle instead and try to correct it that way.

That sounds like a throttle control issue - if you are not rolling on the throttle ENOUGH, you may be slowing down, which will tighten up your arc, making you have to steer the bike to the outside to keep it on your desired line. Do you recall, from Twist of the Wrist or the Twist II DVD, how MUCH acceleration is required for good throttle control? Anyone else want to chime in on that? If you are sure that you are rolling on the throttle enough to maintain at least a slight acceleration, it could be a suspension issue, the front end 'packing down' and causing the bike to steer in tighter - in that case, stiffer on compression and/or looser on rebound might help. But I'd for sure try doing a more progressive throttle roll-on first, that is most likely to fix it. You are using the term "maintenance throttle" and I think that can mean different things to different people - what does it mean to you?

I'm not quite sure if you are talking about the school policy, or personal preference - so just to be clear, in Cobie's example, the student crashed and hit his head, at the school. Therefore he was not allowed to keep riding that day, that is school policy. The school cannot safely determine if someone is ok to ride after head impact; it wasn't like Cobie just randomly noticed a scratched helmet and told him he couldn't ride. Obviously in other circumstances, only you would know what sort of history your helmet has, and it would be a personal judgment whether to continue using one that had been in a 'minor' fall. Personally I'd rather ride in a $200-$400 helmet that has never hit the ground than a $700 one that had been through a crash... Since racing rules require a new helmet at least every 5 years and recommend it every 2 years, I just stopped buying $700 helmets! Anyway, I think it is free to have a helmet manufacturer check your helmet, that would be a good way to be sure it still offers maximum protection. Something to consider - in reading up on helmets I remember that the major head impact from a motorcycle fall (assuming you don't hit an obstacle) is from the HEIGHT of the fall, not sliding fast on the pavement. Sliding is a less damaging thing and handled by the shell, but the fall from riding height has to be absorbed by the helmet lining material to protect your brain from trauma. I suppose, based on that, a helmet could appear to be almost undamaged but still have a crushed inner liner.

hmm, I'm not a helmet expert either and certainly less expert than most in riding per se. That said, I never heard of the "one time use". It seems like it would be a matter of degree like most other things. It would make sense to disqualify the lid if you knew for certain that the helmet protection was compromised --shell or padding. But would a little scuff ("minor scratch") as a result of a fall where your head contacts the pavement disqualify that helmet absolutely? How many of us would trash can a $700 helmet for that? How many helmets have fallen off bikes and gotten scratched. There no head in it, in that case but still... I am not suggesting we be cavalier with our head safety but there must be some reasonable way to decide that without a black & white, yes or no rule for helmet contact. I know Shoei (for example) will inspect your "damaged" helmet and let you know if it is still doing its job as specified and therefore safe to continue using. You don't see riders throwing away racing suits after an off (usually). I respect that you have your rules at Superbike and maybe you are right to have them. It just seems like DQ'ing a helmet for any contact is a bit extreme. I'm not an expert either, but I have read up on this, mainly researching whether the costlier helmets really provide any better protection than the mid-range helmets, so here is my understanding: The problem is that the material inside the helmet is crushable, that's how it absorbs impact. After being crushed, it doesn't spring back to shape and thus has lost its ability to protect you in another impact. That crushable material is between the outer shell and the inner padding, you can't see it, so the ony way to check it is to send it (as you say above) for inspection by the manufacturer. In a crash, the inner material is crushed by your head's inertia inside the helmet - so the shell hits the ground, but the crushable stuff between head and shell cushions the impact, slowing your head down and helping to keep your brains from slamming into your skull, and /or your skull crushing on impact. Personally, if my helmet fell off a bike, I would be a little concerned about its protectiveness after that but I probably wouldn't junk it - since there is nothing heavy INSIDE the helmet to crush the inner liner in the fall. And yes, that could potentially scratch the helmet paint a bit, but in my limited experience, that does not look like the broader scuffs that occur from an actual crash impact. However, if a student crashed, hit their head, and there was visible damage to the helmet, I would absolutely not think it was wise for that person to continue riding, it's too difficult to tell if someone has a head injury or not; they might think they are fine when they really are not.

So I have a new chain on my bike. It's covered in white goop. I did a short ride on the bike (I'm also breaking in a new piston) and that new chain is throwing gunk EVERYWHERE, including onto my rear tire! I've asked three people (so far) about whether I should clean that factory grease off and gotten the following answers: 1) Get the chain hot, use a cleaner/degreaser to get all that ###### off, then spray it with Chain Wax, DON'T use Chain Lube 2) DON'T clean off that stuff, it came with the chain, it is necessary and if you clean it you will be compromising the O-ring design of the chain 3) Wipe it gently then re-spray it with Chain Lube, DON'T use a cleaner, and DON'T use Chain Wax. SO, with that selection of completely contradictory answers, I'm not sure what I should do! What do you do with a new chain, do you clean and re-lube, or just wipe it down...?

Wow, great diagram! Thanks for posting that, especially with the photo below it, that communicates the concept very clearly, well done!

Holy smokes, it's pretty hard to compare lean angles when one bike is in front of the camera and the others is behind - or under? - the camera! But, here is something I did notice - the rider being filmed (the one in front) for the first part of the video is not hanging off effectively. He is sticking his knee way out and rotating his hips off to the inside, but if you look closely at his upper body it is crossed up - he leans back over the bike with his upper body so that his helmet is actually at or past the centerline of the bike. You can REALLY see it in the preview photo - see how the bike is leaned to the right but the rider's head is actually closer to the LEFT mirror? He is pushing the bike down underneath him, instead of leaning his upper body into the turn. So although he gets PART of his body mass to the inside, a good part of it (possibly the heaviest part) is either on top of the bike or even a bit to the outside. He isn't moving the combined Center of Gravity very much, if it all, so his lean angle is probably about the same as a rider who isn't trying to hang off. In contrast, the rider that is filming DOES seem to get his/her head off to the inside, and presumably the upper body with it; you can't tell much, but if you watch the position of the mirrors relative to the camera, you can kinda tell. Towards the end of the video we see another rider that is sitting straight up (but does go nicely with the bike, no counterleaning). That rider doens't use a lot of lean angle, but it appears to me that it is a lighter-weight bike and he doesn't seem to be going as fast, so he wouldn't need to use as much lean angle to get around the turns.

Not true I'm afraid. The amount of centripetal (cornering) force produced, as Hotfoot says, depends on the amount of weight and how far inwards (horizontally) it is of the contact patch. This varies with lean angle of course, and a tall bike will thus produce more of it than a short one at the same lean angle. If you watch the attached diagram with your head tilted to the right, you will see a bike rolling on one side of the tires, over an inclined road, and carrying a weight somehow higher than its natural weight (bike+rider). The leaned bike is balanced because all the forces go to ground through the tires, just like when it is traveling in a straight up position. When properly leaned in a turn, a motorcycle is as stable as when perfectly straight. The reason being that the weight of the bike plus the forces generated by the circular movement don't point vertically down but towards an angle between vertical and horizontal. Hence; the height at which the CG is located has no influence on the total (bike+rider) lean angle. The confusing/misleading part about the statement above is that we are not trying to change the COMBINED bike PLUS rider lean angle. We are just trying to change the BIKE lean angle. The diagram above shows the simplified model using one combined center of gravity for both bike and rider. Hanging off changes the relative position of bike and rider to each other, which means to see the actual BIKE lean angle you have to treat the the bodies (bike and rider) separately. We all know from experience on motorycycles and bicycles that if you lean YOUR body way into the turn, you can stand the bike up more and use less lean angle, and that if you lean your body AWAY from the turn, you have to push the bike down underneath you (steeper bike lean angle) to balance. The lean angle of the COMBINATION of bike and rider does not change (for a given mass, speed and radius) but when you change the relative position of the bike and rider to each other, the RIDER can lean in more while having to lean the BIKE less.

Ah - good point. I didn't mean to imply that hanging off is ALWAYS necessary. It's just a solution to the specific problem of running out of lean angle. If you aren't in a situation where you are running out of lean angle, or just generally need or want to use less lean, it may not be useful. I agree that hanging off while riding in the street can be a waste of energy and could compromise your vision. I don't ever hang off while riding on the street, because I don't go fast enough to need to, nor do I hang off during slow sighting laps, where I need to sit up and look around. I just don't agree with the statement that it is "overrated", because it solves a very significant problem! Crash - your description of people hanging WAAAY off when the bike is barely leaned over made me grin, and made me think of the people that put giant lift kits and huge wheels on their truck but then never take it off city streets. A bit of overkill, perhaps...

I think a LOT of things seem overrated until you need them. Like race tires, for example. It seems crazy to spend 3x the price on fancy race tires... until you start overriding the grip on a street tire. Or telemetry, that seems like a massive waste of money... until you are trying to get an extra 0.2 seconds off your lap time and really need some data to figure out where to get it. Most riders find, as they progress, they hit limits, and when you hit a limit something has to change. When I first started riding, quick turn didn't make much sense to me - until I increased my entry speeds, then I NEEDED that technique. I didn't get the importance of pivot steering until one day I realized that if I went any faster through a certain corner I wouldn't be able to get the bike turned. Suddenly the technique became relevant, for me. On the other hand, the "relax" drill was something I needed RIGHT AWAY, and it made a massive difference for me on my very first school day. I notice, at schools, rider learn various techniques and apply them, but inevitably at least one of the tecnhiques makes a sudden HUGE difference in their riding - because THAT is the one that breaks through their particular barrier at that moment. And they pick up the pace, and then they hit a new barrier. And it requires a different solution. The feeling of breaking through those barriers is incomparable and that is one of the main things that kept me coming back to the school, over and over - it's very hard to do on your own and very easy at the school.

It suddenly gets a lot more important when you run out of lean angle! If you are at MAX lean, starting to drag parts, but you want to go around the corner faster, you either have to MOVE that Center of Mass, or REDUCE the mass! Hanging off is cheaper than carbon fiber parts and quicker than Weight Watchers... As far as hanging off when riding at a relaxed pace or when not leaned over much... well, you have to start somewhere and it's a lot easier to practice and find a comfy position and build strength at a moderate pace and shallow lean angle - it's pretty tough to all of a sudden dramatically change your position when you decide to pick up the pace, too many things to worry about all at once. Also, to warregl's point.... it looks cool.

I like to think of it this way: the rider that is hanging off can use LESS lean angle for the same turn, same speed, etc. The reason hanging off helps is that it moves the combined center of mass of rider and bike down and to the inside. When doing physics problems, it is workable (and far simpler) to calculate forces acting on a body by identifying the Center of Mass of the body, and calculating the forces as they act upon the Center of Mass, instead of trying to treat the body as an infinite number of tiny parts. When you are going in a circle, inertia wants you to keep going in a straight line, instead of on a curve. Some force is required to make you turn. That force is called centripetal force, and on a bike the centripetal force is provided by the friction of the tires on the pavement. (If you were whirling a ball on a string in a circle, the tension on the STRING would provide the centripetal force, and that is one of the simplest models to picture.) The centripetal force provided by the friction of the tires is a horizontal force, which acts to keep the bike on the circle. However, since the tires are on the ground, and the Center of Mass of the bike/rider is a a few feet (or so) higher and we calculate the force of inertia as it acts on the Center of Mass, the forces are not in alignment and this creates a "moment" which wants to rotate the center of mass towards the outside of the circle - making the bike want to "fall" (rotate) to the outside. When a rider leans the bike into the curve, the force of gravity on the Center of Mass of the bike/rider is no longer pushing straight down to the tires, it is offset the inside, which creates a "moment" which makes the bike want to rotate inwards - to fall down to the inside of the curve. At a certain lean angle the forces balance, so the bike can go around the curve without falling inwards or rotating outwards. Centripetal force is calculated as: mass times velocity squared, divided by the radius of the turn (mv2/r). So the force on the tires is dependent on the weight of the bike/rider, the speed, and the radius of the turn. That doesn't change. What CAN change is the location of the center of mass - if you hang off, you can do two things: 1) You move the combined Center of Mass lower, which means the "moment" that wants to rotate the bike to the outside is less (because the offset distance of the horizontal forces is less - the C.O.M. is closer to the ground) AND 2) you move the Center of Mass to the inside, which creates a GREATER horizontal distance between C.O.M. and the point of contact of tires to ground which increases the moment (from the vertical gravity forces) that wants to rotate you to the inside. So the effect would be that you either have to stand the bike up more to keep from falling inwards - OR you can go faster or tighten the turn radius, either of which increases the centripetal force and puts the forces back in balance. This is a bit oversimplified (other forces are present, like wind drag, etc.) but hopefully it communicates the idea.

Yup, I agree with all of the above - I think when you have a high horsepower bike you need that larger contact patch so you don't just rip the rubber right off the tire. My little 40 hp Moriwaki has a skinny rear tire, as does my little 200cc (4 stroke) dirt bike, neither has a lot of horsepower and they don't wear out the rear tire like a high horsepower bike would. In fact, in my last race weekend, I realized my FRONT tire wore out (on the Moriwaki) before the rear tire. That never happened on my 600, and my husband goes through 2-3 rear tires on his 1000cc before changing the front.

I'm not sure if this is well known outside the US, but there is an old prank called a "Hotfoot" where you would stick the end of a match in the edge of someone's shoe, and light it, with the idea that when it burned to the end it would sting their foot and make them jump. It has also evolved to mean "go fast" as in "you better hot-foot it on down to the store before they close!" But Kai asked how I got that nickname, so here you go: I was driving a retired NASCAR racecar at a race school. As I was getting up to speed and shifting to 4th gear I smelled a little bit of a burning smell. I didn't see any smoke or anything so I thought maybe it was just the clutch getting hot - but then as I came around Turn 2 onto the backstretch, a piece of insulation fell out from under the dash onto my feet and it was on FIRE. Yikes! So I shut off the engine and as I reached the backstretch (coasting in neutral, at about 100mph) I pulled off onto the apron and stopped. That turned out to be a bad idea because as soon as I stopped the car filled up with acrid and choking smoke, and since I was on the backstretch I was not close to any emergency vehicles. It is surprisingly difficult to extricate yourself from a stock car without help; you have to take off the steering wheel, release the harness, unfasten the safety window, and then climb out through the window opening, all while wearing a HANS device (and a helmet) that prevents you from looking down or ducking your head. But I was highly motivated! So I managed to get myself out and then I ran from the car because it was really burning by then (the windshield was melting!) and I was afraid it would explode. A thick column of black smoke was coming up from it, I learned later that my friends in the paddock, who were on the opposite side of the track and couldn't see anything BUT the smoke, were afraid I had crashed into the wall - especially when they saw the two fire trucks and the ambulance heading that way. Anyway the fire trucks arrived a moment later, and eventually were able to get the fire out. Something in the fuel system had broken off and was squirting race fuel into the engine, which caused and sustained the fire. I rode back to the paddock in a fire truck and my friends and co-workers were relieved to see that I was ok; they all crowded around and asked me what happened. I told the story much as I have told it here (except that I was covered in black soot when I was telling it to them, which may have added to the ambiance) and someone jumped on that image of the flaming insulation falling on my feet, and started calling me Hotfoot. The name stuck, as nicknames will do.

Hopefully Steve can answer this in a much better way - but here are my thoughts, for what they are worth: 1) for sure, the real-life situation is not as simple as that equation - there are additional factors like tire flex, tread flex, heat, slip angle, tire deflection, etc. that make the basic static friction formula above not adequate to define the actual traction you experience while riding 2) I don't think the coefficient of friction can be assumed to be constant in this application, because if you had a very small contact patch you could (I think) overload the tire, overheat and melt (or possibly tear) the top layer of rubber, and now you have different coefficient of sliding friction because you are slipping on melted rubber. In other words, the "surface area" component you are looking for may essentially be hidden within that coefficient of friction number. I'm sure there is way more to it than that, but I'm confident that the article above is a vast oversimplification based on static friction and the "ideal conditions" that always became a joke in my dimly-remembered physics classes. (Example: "assume a perfectly spherical body on a perfectly frictionless surface....")

LMAO! That is priceless. Maybe Pete can photoshop a mock-up for us...

OK... gotta know... is there more to the story about the big Harleys? Do you have a collection of dusty leather vests in your closet?

Resurrecting an old topic - following the FZ-1 video I stumbled upon this. The difference in smoothness and control between the two is very noticeable. Wow, you can see a LOT of examples of throttle control errors in this one! Here are some that I saw, in various spots on the video: Delayed (late) roll-on, often followed by abrupt / too aggressive roll-on Too EARLY (before steering was completed, and he goes wide and almost off the road) On and off the gas in the midst of the turn And then at the end, he clearly has a scary moment, which slows him WAY down - what do you think happened there? Also, did you notice any steering corrections mid-corner? I was lucky in that I went to the Superbike School BEFORE I tried riding fast or aggressively on mountain roads - it must be very frustrating for a rider like this to feel the instabilities of the bike and have those close calls, and not know the mechanics of what is happening or how to fix it!!!

I can't tell from your post if you could SEE the throttle position on the videos, or if you were assuming the throttle action based on the RPM, but that opens an interesting discussion, that might also answer Jaybird's question about throttle control. Let's look at the relationship between RPM, and speed, and throttle, in a corner... 1) If you enter a high speed corner (say, 60+ mph entry banked sweeper), and keep the throttle closed, what happens to your speed? 2) If you enter a high speed corner, and just SLIGHTLY crack on the throttle, what happens to your speed? 3) When you lean the bike over, what naturally happens to your RPM, as a result of riding on a smaller-diameter part of the tire? What happens to the RPM as you start to stand the bike up?

You start your roll-on as soon as possible, once you have completed your steering action. It is not workable to tell you exactly WHERE in the corner that will be, because every corner is different - if I told you to start your roll on "halfway between your turn point and the apex" that might be fine for one corner, but too late or too early for another. At the school, we demonstrate the roll-on point for various corners by leading the student and giving a hand signal to show exactly where the coach begins the roll-on. We do NOT wait for the apex. (To be clear, when I say "complete your steering action" that does not mean necessarily mean you are going straight, it just means you are no longer pushing on the handlebar to change the bike's lean angle and direction. Example, I reach my turn point, steer the bike, then relax the pressure on the handlebar and start my roll-on to stabilize the bike, on the arc that will carry me to my apex.) Many new riders steer the bike very slowly (no quick turn) and for them it may take half the turn to complete the steering, so they tend to have a late roll-on. Once they learn to quick turn the bike then get right back on the throttle, their cornering and control of the bike improve drastically.

This sounds rather complex, and it requires you to add a steering input at a point where you are at near-maximum lean, and have the front heavily loaded due to deceleration and cornering forces. It seems like you would have to put a LOT of attention on your front wheel traction, to make sure you don't overload it and lose it during that second steering input. What problem are you trying to solve, exactly? Why is it necessary to only lean 90-95% at the beginning of the corner and wait so long to apply the throttle, versus just making one quick turn input straight to max lean, then starting your roll-on? Also, we never really answered the question of how MUCH to roll-on, did you have a chance to look up EXACTLY how much roll-on Keith recommends, and why?