racer

I need to preface this post by noting that I misused the word centripetal when I meant centrifugal in the last paragraph two posts back and inaccurately used centrifugal in my last post. I will edit it before some mechanical engineer or physics expert bites my head off for it. My bad. Actually, all mass falls at the same rate, so, a golf ball would do to isolate the vertical acceleration offered by gravity. Based on the known acceleration of standard Earth normal gravity, ie. 9.8m/s/s, one could extrapolate a one meter fall at perhaps 1/10 of a second or a little more. But, the point is that, as we both said, the bike isn't just falling, it is rotating on the z-axis which must, IMO, include a horizontal component of force to initiate as the front wheel doesn't get very far out of track before you are over. IMO, the closest practical test to isolate the effect of gravity from forward momentum in a similar scenario would be to simply allow a motorcycle to tip over from a stationary position. Perhaps cocking the front wheel first to approximate the counter-steered position? I disagree that the center of mass is the fulcrum of z-axis rotation for the machine as it leans over. If you watch a video of an oncoming bike being counter-steered, you can clearly see that it only moves a few inches off track. If the CoM was the fulcrum, the wheels would move as far off track as the top of the bike. I believe that the contact patch is the fulcrum that our moment arm attempts to rotate from in this instance. However, turning the front wheel causes the bike to move off track as it initially attempts to track in the direction you steer before the bike leans in. Well, I think we are doing more than knocking the front wheel out from under the bike. I think we are attempting to steer the bike and the front wheel tracks the way you steer before the bike leans in. And, for the pedantic minded, to be scientifically accurate, when the input is released, a centripetal force is created at the contact patches as the bike begins to track an arc after it leans which creates a centrifugal effect in the opposite direction. And opposite of the one that knocks it over as the bike attempts to continue in a straight line when you turn the bars. Just like a car. Turn right hard enough and you're going to have a lap full of passenger. IMO, this is essentially the same thing as what happens to the bike when you steer it except that there is nothing to catch it until you let go of the bars and it begins to track an arc. I guess, technically, it isn't a centrifugal effect if there is no centripetal force. So, again, for the engineers out there, to be scientifically accurate, the bike merely rolls over as it attempts to continue straight, whereas, the interior surface of your car door holding the passenger from falling out in a left turn provides the centripetal force there. The bottom line, IMO, is that it is the same type of process and forces at work, except that the bike doesn't have four wheels, so it falls over. But, driven by the same type of force that drives that passenger against the car door. I apologize for posting in such a hurry and not taking more time to explain and clarify the more scientific concepts for the laypersons here. I will return when I have more time and try to do a better job of this. Just to reiterate, I think gravity DOES play a part in the bike rolling over. But my gut says that forward momentum plays a significant role in initiating that roll. I will try to think of a good experiment to isolate THAT idea.

I don't mean to shift the topic from gyro forces to steering the bike, but, this seems to be the salient point of the major premise, ie. gyro forces turn the bike. So... A simplified analogy would be balancing a baseball bat and pulling the bottom out from under it about an inch vs. pushing the top over. I think this is the basic difference between the idea of a bike "falling over" due to gravity and "flicking over" due to counter-steering at speed.

Hey Dan, Counter-steering into a right hand corner typically leads a rider to push on their throttle hand to initiate the turn in. You might try combining some pull on the outside handlebar and see if that helps. Also, try to notice if you might be weighting the bars in general, ie. are you holding on or holding yourself up with the handlebars? While steering? Or braking? (Are you trailbraking while turning in?) It is easy to fall into a habit of "leaning" on the inside handlebar with your upper body to initiate a turn rather than locking on elsewhere and pivot steering from that lock-on point, especially with a "very upright riding position". Ideally, you want the lightest grip possible and zero body weight on the bars at all times. Good luck, racer PS - You didn't mention whether you had read any of Keith's A Twist of the Wrist books. You will find far more complete information in more detail and easy to reference form than can be gleaned by tossing out questions here.

Hello, Willie! Welcome back and thanks for posting! I completely agree with you re: gyroscopic precession and its relationship to turning the bike. That said, there seems to be an ongoing idea that gravity is responsible for a bike leaning into corner, ie. the wheels are steered out from under the bike and gravity causes the bike to simply fall into the turn. I do not accept this. There is exponentially more energy/force bound up in the mass and forward velocity of the bike than mere gravity at 9.8 m/s2. Especially when the inital motion is horizontal and rotational overall, ie. how much force can gravity exert in the horizontal at a lean angle of 2 degrees from vertical? 5 degrees? 10 degrees? Does the bike only start to flick fast at 30-45 degrees of lean angle? IMO, the forward momentum of the bike is the primary mover and the major force behind counter-steering that causes or intiates the lean and defines how fast a bike will lean over when counter-steered. This isn't to say that gravity has no effect, merely that the primary mover is forward momentum and a centrifugal type of effect. (Not really centrifugal to be pedantic, but, I will explain later.) So... can a bike flick faster than gravity causes it to hit the ground if you simply let it fall from a stationary position? Even if you give it a head start by steering it out of its track? I believe so. I think that there is more than mere gravity and offset center of mass going on here. The faster or further you turn the bars, the faster the bike will lean or roll in the same way that a car will roll more/faster the harder you yank the steering wheel. Simply put, when you steer the bike left, it tries to continue in a straight line. Newton's Laws? This creates what would be a centrifugal effect with no centripetal force to control it (until you let go of the bars and it begins to track a radius at lean). The motorcycle, being inherently unstable (unlike a car with four wheels), there is nothing to stop the rollover, so, over it goes. However, a car will roll and lean the opposite way right up onto two wheels and further if you (counter-) steer it hard enough. Is that due to gravity? Consider that the bike isn't simply falling. The top is moving more sideways than downwards until it reaches 45 degrees of lean angle. And that top moves far further than the wheels are steered out of track. So, forward velocity/momentum looks the likely pool of energy to me that is being tapped by the geometry. That forward velocity/momentum causesg the bike to fall off balance and z-rotate or initiate a "roll" or lean. Just like yanking the steering wheel in a car causes it to roll in the opposite direction. What other pool of potential energy are we tapping to initiate that horizontal component? Vertical gravity and height? I think not. What do you think? Anyone? Cheers, racer

My gut says that the difficulty you are having understanding Vittore's words might have something to do with Italian being his native tongue and everything being translated with odd syntax and grammar. The JonesBoy post is a really good plain english wrap around the basic issues and/or (mis-)conceptions presented in this thread.

Welcome Dan! We will endeavour to assist your efforts in any way possible. Cheers, racer

Cool. I didn't mean to imply otherwise. Me too. About 1-2 seconds for the average street rider. Perhaps 1/2 (0.5) seconds or 500 milliseconds for a fast racer. Not sure I follow exactly what you mean here, but, hanging off isn't about increasing how fast you flick, it is mostly about reducing the lean angle you must carry through the turn for a given speed. Hence, if you are at max lean without hanging off, you can go faster through the turn if you do hang off. And, then, be able to complete the middle of the turn and lift up earlier to accelerate harder for the exit sooner. And... hanging off before you flick is about stabilization for the flick process, not flicking faster. For what it is worth, I am responding here to my interpretation or imputation of your interpretation of Vittore's words. Aside from the quote you posted, I haven't read them myself. And being that so much is missing from this thread, ie. Willie's posts, I'm not even sure what the premise re: gyroscopic effect here is. r

Oh. I just found the quote funny because in plain English it basically says, "any gyroscopic effect is offset or balanced by other forces at a stable lean angle." Well, duh. Hence why it is called a STABLE lean angle perhaps?!

Hear, hear. Thanks for the update, Red. And the book. Keep 'em coming.

Who is Vittore Cossalter? And where did you find that hilarious quote? Not in this thread. Not unless you completed high school physics anyway...

What happened to Willie's posts in this thread?

Bonjour et bienvenue Genevieve! Compliments pour votre victoire en Mosport et bon chance en Shannonville! Meilleurs souvenirs, racer

Hi Chunger, I don't have time this am to get into a detailed reply to all of your questions, but, I will try to touch on a couple points that stand out for me. Having four-wheeled manual transmission experience is good, but, remember that the controls are opposite: shift with feet, gas/clutch with hand. This and other not so minor details lead me to recommend most people do not learn the basics of operating a motorcycle on the street. I, and most everyone I know, began off-road, or at least off public road/highway, on some kind of basic trail bike. (Not motocross.) That isn't to say that a 250 Ninja and a parking lot won't suffice, just that there may be another option better suited to learning this skill. MSF is good place to start, but, CSS is not for beginners learning to operate a motorcycle. As such, making a savings plan/budget is a good thing, but, honestly, it's a little early to be booking a 2-day camp or single day classes until you have some seat time. Probably six months to a year minimum, in my opinion. That said, I'll let someone else extol the virtues of a 2 day camp vs the single day schools. I think there are already several threads devoted to this topic already. Good luck, racer

Hi Poncho, I agree with Stuman. The "no brakes" drill is the ultimate tool for evaluating and increasing entry speed. I also agree it is valuable to follow your nemesis around to see where he is faster, if nothing else. You said he is on an HRC kitted 600. The kitting shouldn't have much effect on entry speed. But, what bike are you on? Are you also on a 600? If you are on a bigger bike, you might not be able to enter as fast, but, you should be able to make up time on the exit if you quick turn fast enough to complete the turn sooner and pick it up early enough to utilize your superior horsepower for a better drive down the straight to the next bend. I would also suggest that you might be able to gradually increase your entry speed by adjusting your braking zone such that you let off the brakes a little earlier each time. Try letting off sooner and sooner so you gradually increase your entry speed yet leaving yourself some space to correct if SR's say you are too fast. You will need to be very aware of your braking zone markers/RP's to use this technique. Cheers, racer

Load the bike on elevation changes---do you mean cornering load for uphills and downhill sections? Yes. What do we need to consider when cornering uphill or downhill? I think good throttle control is the key there. A few weeks ago, I turned a bike very quickly in a chicane, and had a little throttle on (little too much as it turns out). Front came off the ground, and when it landed was cocked a little (thought I was on my head). Good TC is vital at the corkscrew too, reminds mne of that chicane in fact, which is uphill! I have no problem with the top of the corkscrew. It's Rainey curve (I think), the long left hander in the middle that used to have a bump (transition) exiting on the gas that bounced the front of my 125 over about three feet even after softening up the forks. I really gritted my teeth there. (I think it has been re-paved since I last rode there.)

Hi Poncho, Am I to understand that this racetrack is in India? I knew there was organized racing there, but, I did not know there were such modern and beautiful venues. What is the name of the track? What part of the country is it in? Thanks, racer

Hi YooiY, I don't see/understand what you mean re: "...head tilting away from the corner". Can you explain more? Thanks, racer

Load the bike on elevation changes---do you mean cornering load for uphills and downhill sections? Yes. What do we need to consider when cornering uphill or downhill?

Hey Steve, I don't know of any reports of this kind off the top of my head, but, it should be a simple thing for you to track some down with a search engine. I imagine each manufacturer do their own testing in house. Road Racing World magazine used to do glove "crash test" articles/reports by having readers send in photos or examples of crashed gloves to analyze. Perhaps John could hook you up if you think that is important. Cornerworking groups should have a good deal of first-hand data, if not written reports. FWIW: My mentor used to tell me that if I found the problem, it was up to me to fix it. And if it's my idea, there's nobody better qualified than me to make it happen. Whatever compassion or energy that makes your "mind go into gear", that is the single most important quality to seeing an idea or project through to completion. I think you could make the difference. I say run with that intention, tap into that mental energy and bring your idea to the attention of glove manufacturers and convince them of the need and market for such a protective "gauntlet". If that fails... DIY. Let me know what you find on those reports. racer

Here are some photos of Road Atlanta Turn Five to go with my last post: (entry) http://www.paulspruell.com/motorsport/pfsp...tlanta_1985.jpg (exit) http://www.tradebotics.com/2002/Road%20Atl...20and%20320.jpg

That can be a more complex question than it might seem at first glance. First, the basic bias goal and standard throttle remain the same. Just like a flat corner, I want to match the relative tire loads to the relative sizes of the contact patches, typically 40% on the front and 60% on the rear. Ignoring any crests, the rub is how much more or less acceleration you need to achieve this bias on a hill. It is easy to see that if you are traveling uphill, static bias is offset to the rear and vice versa when traveling downhill, ie. there is more weight on the rear tire when pointed uphill than when the road is flat, and, when pointing downhill, there is more weight on the front. So, it is easier to overload the front when going downhill and it takes less power to spin up the rear. Going uphill, the challenge is to keep enough load on the front. However, there is more to consider due to the 'natural' camber that can be created by the 'fall line' of your particular hill. Take for example Turn Five at Road Atlanta where Josh crashed last week. It is a deceptively fast corner due to the relationship between the fall line(s) of the hill and the corner creating a postive camber or "banking" which allow a rider to throw it into the turn quite hard as the line is across and into the fall line of the hill. However, T5 is even more complex because there is more than one fall line to it and, passing the apex, the road surface is now also going uphill in the new direction of travel. Additionally, the road surface dips (or used to dip) toward the inside near the inside curb like some other corners we've discussed recently. Not until the exit does the road surface 'level off' (side to side) at which point your positive camber goes away. So, although it is a fairly tight corner, there is a good deal of natural "banking" to be utilized and it is really a much faster corner than it looks. Are you with me so far? (entry) http://www.paulspruell.com/motorsport/pfsp...tlanta_1985.jpg (exit) http://www.tradebotics.com/2002/Road%20Atl...20and%20320.jpg

Welcome to the forum, Black Snowman. Why are you planning to choose Streets of Willow for your 2-day camp? What comments are you refering to?

Thanks for the heads-up, Shane. Our prayers are with Josh and his name is now on several more prayer lists. Based on Eric Dorn's write up on the WERA page... I've never met Josh, but, I'd sure like to. "Our sport needs 100x guys like Josh..."? I'd say our planet needs 100x more guys like Josh. BR, BH PS - Having had my left hand essentially torn off the end of my arm, crushing the distal ends of the ulna and radius, "horribly comminuted wrist joint" as the bone doctor put it, and currently recovering from a C6 dislocation, crushing a nerve, leaving my left arm half numb and half in excruciating pain for two weeks now, with no prognosis... maybe it will get better... maybe not... I have some idea. What we give for our sport. I came here tonight to write a response to Misti's words about how many friends I have lost, how many friends I have watched die on the track in real time right in front of my living eyes... and now this... sorry, that's enuf one handed typing tonight. i should stop before I get too maudlin... Get well soon, Josh.

I envy you, mate. Godspeed and have a safe ride, Bobby. Come back alive and tell us all about it!

Ditto. Earlier you seemed to be turning in too early and too slowly. Later you seemed to be flicking a bit quicker and later. Still room for improvement. Look at the difference between your turn in/points and the coaches' turn in/points.