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Hotfoot

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Everything posted by Hotfoot

  1. I get the idea, and it makes sense intuitively, BUT... if trail is dependent on the steering head angle, and the steering head angle is mechanically FIXED on the bike, how does the trail actually change? Also, if you draw out a picture of a bike, draw the vertical line to the ground and the line extending the angle of the forks to see the trail, then SHORTEN the forks (compressed shocks) and redraw the trail, it doesn't change... because the wheel radius doesn't change, and the rake doesn't change. Not unless you "allow" the forks to rotate at the steering head, changing the rake angle. Trail=RSinø-0/cosø R=tire radius 0=triple-clamp offset ø=rake I do see that rotating the whole bike forwards would shorten the wheelbase, but don't see that it would change trail. Sorry if I sound a little argumentative, I am not trying to be, I am just frustrated because I don't quite understand this and it's bugging me!
  2. Harnois, nice explanation about rake and trail, thank you for that. To answer your later question, about whether the cruiser always wants to stand up: I experimented with that a lot on the day that I noticed it happening. I tried turns off-gas, maintenance throttle, light acceleration, and hard (kinda) acceleration. Off throttle it was nuetral, maintenance it stood up slightly, light throttle it stood up a LOT. Hard acceleration didn't seem to affect any more than light roll-ons. I'm still a little suspicious that the thing is squatting a lot, the suspension on it is very soft and not adjustable. Stu, I totally agree with your explanation about the bike standing up under braking. There is a GREAT computer animation of this in the Twist of the Wrist II DVD, that is what finally made it click for me. I also agree with your head-exploding feeling, I read the Tony Foale stuff too. Harnois, you said: "Getting on the front brake causes the bike to dip forward, which decreases trail" I was thinking about that, and I don't really see how the front of the bike dipping forward would change the trail, are you sure that it does? I think trail is dependent on rake, not fork length, and I think rake is fixed mechanically by the bike. Am I confused? I was thinking this over because since we started this whole discussion, I also started wondering WHAT actually causes the front wheel to turn when you hit a bump while leaned over. We know it does, but why? I think it must be a similar thing to why it stands up under braking...?
  3. I took my little cruiser bike out for the first time in a long time, after doing a lot of sportbike riding. It's a Suzuki Savage 650. Obviously it steers differently than my Ninja. But one thing in particular jumped out at me. One of the things my coach told me at school is that once the bike is leaned over in a corner, getting on the throttle does not make the bike stand up, that it maintains the same lean angle. OK, fine. However, when I lean over that cruiser, and get on the throttle, it stands up noticeably. It is most pronounced at low to medium speeds, like 20-40 mph, but it took me by surprise a couple of times until I got used to it. I never really noticed it before - probably because I thought ALL bikes would stand up when you roll on the gas, so I used to maintain some pressure on the bars to "hold" the bike in the turn. I don't do that anymore. So... what's the deal? Is it because it has a much shallower steering angle and/or greater trail? Or is it because the suspension is soft and the rear end squats under acceleration, changing the trail when I get on the gas? I'd really like to have a better technical understanding of how this works, anyone want to help me out?
  4. What track day are you doing at Fontana? Mar 29th?
  5. I notice that , too. I often do the same thing on the street, and/or anytime I am going really slow. Rolling the throttle on stabilizes the bike, right? Which is what makes it a little harder to turn - BUT when you are going REALLY slow, the bike feels pretty wobbly so a little bit of "maintenance" throttle during your turn-in can make it feel more stable. It compromises your quick turn, but... let's say you are going to turn right on red, so you are approaching the corner slowly, while looking hard to the LEFT for oncoming traffic. In that case, stability seems more important than getting a high entry speed or snappy quick turn. So, in my opinion, there is nothing wrong with using that bit of maintenance throttle when you are going slow, to help stabilize the bike. However, if your goal is to have a higher entry speed, THEN you'll need a good quick turn, right? Getting off the throttle makes the bike easier to turn quickly - and you have already discovered what you can do with your turn point when you quick turn! Sounds to me like you are just experimenting with quick turn and finding out what happens with your turn point when you turn quickly, and when you don't, which is awesome, very observant and thoughtful on your part. I think both of the options you listed (turn in with maintenance throttle, or using a later turn point and turning it off-throttle) are "OK", depending on the circumstance, and on the entry speed you are trying to achieve. If you have the Twist of the Wrist II DVD, during the quick turn discussion, there is a nice shot of a guy on Harley making a rather leisurely turn on the street, and that's where the point is made that you only turn the bike as quick as the situation demands, it's a good example and certainly made it more clear to me.
  6. I think at that point he is a frame slider!!!
  7. Hey Crash, I want to support what Bullet said. The first time I came to school I was riding right about the same level you describe in your post. I was comfortable with shifting but very tense and slow through corners, nervous about traffic, and not very willing to really get on the gas. I called the office with questions like: "will I be able to manage a 600? What if my feet don't touch the ground?" However, it was ME that made the decision to come to the school, and I brought my husband along with me. I wanted to learn to ride a 600cc bike. If I had been dragged to the school, I would have been scared half to death and probably inclined to blame whoever talked me into coming! But, here's the thing - my coach (it was Stuman, incidentally) was patient and it was very easy to trust him, and I did the drills at a slow-to-moderate speed, and by God, I improved so much in one day it was... well, I don't know how to describe it, but I fell in love with the sport, came back for lots of schools, and now I can hold my own at any track day (in the fast group!) and I even have done some racing. My husband got hooked, too, we do lots of trackdays and some races together. I am SOOOO glad I came to the school, my confidence shot up instantly and has continued to grow with every school day. Here's something to consider - look for a used Ninja 250, maybe around 3-5 years old. They are easy to find, really inexpensive, have a VERY low seat height, and are super easy to ride and learn on. The older bikes (not sure about the 07-08 models) have weak-but-adequate brakes and weak-but-adequate acceleration, which means you can get really confident with gas and brakes because it is really hard to overdo either one. If your wife is short, she will really appreciate the confidence of being able to get both feet flat on the ground. Anyway, the Ninja is a cheap and easy way to get comfortable with a sportbike, because the controls are the same - a nice step between a no-shift scooter and a 600cc class bike. Coming to school with little or no experience with shifting could be a big distraction - I can tell you that on my first day I was hopelessly worried about dropping the rented ZX6R in the parking lot (because it felt so TALL!) and that sort of worry is exhausting. Good luck with it - and BTW, if your wife wants to talk with a gal who has been there, shoot me a PM and I will send you my email and phone number. HF
  8. This is one of the reasons I come to the school as often as I do! I've been to some track days that were pretty damn scary, especially in the intermediate group. Certainly the track, and the provider, make a big difference, but you still never REALLY know what you are going to get, until you are there in the middle of it. Since my husband and I ride together often, I find myself doubly worried, since he is out there, too! I've progressed from riding the beginner group up through to the race group, and I definitely found the intermediate group to be the most volatile. I am willing to spend a little bit more and come to a CSS day instead, where people are there to learn and the staff is totally dedicated to keeping everyone safe and improving. The troublemakers are handled immediately or thoroughly humbled in the first few laps (no-brakes is brilliant, for more than one reason!). One of the first times I ever went to a CSS school (it was a 2 day camp, actually), there was a guy (student) there who really appeared to be a jerk. By the end of the safety briefing, I was pretty worried about being out on the track with this guy... but Trevor noticed, and pretty soon Keith was having a chat with the guy, and guess what - Keith sent the guy home! I'm not sure whether Keith would appreciate me telling the story, but the truth is, I was TOTALLY impressed. It was the right thing to do, it took guts to do it, and I think everyone in the class was relieved that the guy never made it out on the track. It's a rare track day provider that would notice something like that and take such definite, immediate action, but it's things like that that keep the rest of the group safe and happy. Anyway, my point is, for a little more money I can come to a school, and have a terrific, worry-free day. Oh, yeah, and I improve a lot more, too.
  9. I use clutchless downshifts all the time on the street and sometimes on the track. I've only done it on my own bikes (one of them has a slipper clutch), but on my bikes, if you don't have the RPMs matched, it simply won't shift. I have never felt or heard any indication of a "bad" clutchless downshift, it either goes smoothly and perfectly, or not at all. Do other bikes actually shift, badly, if you don't get the rpms right?
  10. 100% hooked up plus 10% slip. Driving home yesterday, saw an older SUV in front of me with a tweaked frame, traveling forward but also sort of sideways, too, because the back was not quite in line with the front. I could see the back of the truck and part of the left side of it. It must be hell on the tires. And then I thought: AHA! 100% hooked up plus 10% slip! There always has to be some measure of truth in humor. What percentage is truth and what percentage is humor, Hotfoot? 100% truth plus 25% humor. If you are really asking whether I'm kidding or not, well, yes, I think it is funny, but it is totally true and it really did help me understand what Stu meant. Because, since that truck was so crooked, it had to be dragging the wheels somewhat sideways, so the tires had to be slipping. But they were still providing all the traction required to push the truck forwards. Not so different on a bike, right? The bike could still be going exactly the direction and speed you want, solid grip on the road, but there is still some slip in the tire. 100% hooked up, plus 10% slip.
  11. And then what to do you do, roll on the gas? Stand the bike up? Hold your breath and repent for your sins? How often are you able to save it when that starts to happen? Are you more likely to be able to save it when it slides in slick conditions when you are going a little slower and more upright to begin with, or do you save it more easily when you are leaned over a lot and going fast? What percentage of the time do you recover it? A magic formula for being aware when the front tire is about to go and a way to react and save it would do wonders for my confidence. I know I should roll on and/or stand it up but never felt like I had enough warning and time to react.
  12. 100% hooked up plus 10% slip. Driving home yesterday, saw an older SUV in front of me with a tweaked frame, traveling forward but also sort of sideways, too, because the back was not quite in line with the front. I could see the back of the truck and part of the left side of it. It must be hell on the tires. And then I thought: AHA! 100% hooked up plus 10% slip!
  13. Bike suddenly leaned over farther, feel from the front got really quiet, as if the pavement was glassy smooth, and the front stepped out to the right (wide). Then it hooked up, felt like it stood back up a little, and proceeded on. I never moved, because it happened quick and I had no idea what was going on until I felt the abrupt regain of grip. I've also had a front slide that went all the way to a low-side (at pretty low speed) and it felt similar - I turned the bike and got to my desired lean angle, and then it leaned over more (without me doing anything), and I thought, wow, I'm really leaned over, then my knee touched down and then some part of the bike started scraping loudly and I knew I was going down. In both cases the feedback from the front seemed to get really smooth, which I assume is what people mean when they say "no feedback", the bike leaned over noticeably more, and the front stepped out a little wide, making the bike feel pointed to the outside a little bit. For rear slides, I've just felt the back of the bike come out of line with the front; didn't notice a change in feel or feedback from the rear tire. I've never spun it hard enough to hear the RPMs come up. A rear slide under braking (no rear brake involved) feels very similar to me as a rear slide under acceleration - just the realization that the back is getting a little sideways; I assume I am just noticing that my hips just got pushed a bit to the left or right, relative to my hands on the bars! I'm sitting in a swivel chair here as I type, and if I keep my hands on the keyboard and twist the chair a little one way of the other, that pretty much reproduces the feeling.
  14. Quick turn, for me, because WOW you sure can enter a corner faster if you can quick turn it. And guess what, Stuman, you were my coach - I remember following you through a turn, no brakes, holding my breath, hoping like hell this technique would really work because I was SURE we were going too fast to make the turn. That feels like a hundred years ago, now, because my riding has changed so much since then, but I pick that technique as the best thing for me because it made such a dramatic difference in my confidence. The temptation to add ANOTHER best thing is really strong, though... maybe I'll create a new login so I can talk about another technique that made a world of difference for me!
  15. Just my opinion on this... to your point, about using less than your $10 of traction - picture a wide, roughly U shaped decreasing radius turn, after a high speed straight. It will end up a double apex turn, and you don't want to give up your straightaway speed any earlier than you have to. I don't like trail braking but in that scenario I would probably bend it in and trail brake to, or maybe even past, the first apex, because I am still slowing down for my second turn point and the first turn-in is not that sharp, so I have enough available traction to brake while I am turning. In that case, trail braking seems like a good move to keep someone from coming up your inside when you are entering the turn. For sharp, tight, quick-steering turns, it wouldn't even occur to me to trailbrake, it's too much to think about and too easy to overload the front tire.
  16. So... if you think of a corner where you are hard on the brakes on the entry, when you make your steering action, what is the angle of your arms relative to the bars? Is your body position the same when you turn on the throttle versus turning on/after the brakes? Does the angle of your elbow change? Also, just curious - some people push the inside bar to turn and some people pull on the outside bar, some peope do both, which do you use? Do you do it the same way on throttle versus on brakes? Do you find that the bike, when trying to turn while on the brakes, is harder to turn on lefts, or rights?
  17. Rolling off the throttle should tighten the line. Not initially--it will run wider at first. CF First time I heard this, I found it hard to understand and hard to believe. I didn't ever REALLY understand it until I watched the Twist of the Wrist II DVD, there is a computer generated animation that shows what happens, in slow motion, and explains WHY, and WOW did the lightbulb come on for me when I saw that!
  18. Congratulations! A whole new adventure...!
  19. Just a comment on this - I think the Power Ones are dual-compound tires and two things to watch for - first, the edges may wear out before the middle, the outer compound is soft and I think they do have less grip after a lot of heat cycles, so I DO think changing your tires is a good thing to try. Second, on the Power Ones I kept getting the feeling of mild front tire slips in some places, and I finally came to the conclusion that I was feeling the transition from one compound to the other as I started standing up the bike. I would turn it in, and it felt fine, then I started to roll on the gas and it was OK, but after the apex when I started standing the bike up a little I'd get this weird feeling of little slips in the front. My best guess is that when I started getting the tire on the harder compound, it was either sliding a little or just felt really different. One day at the track I changed to the Dunlop Q2s and the problem instantly disappeared.
  20. Don't have to wait for decades, the slipper clutch had already done that for bikes. Just like what DSG transmission and Nissan's SynchroRev Match did to the skill of heel & toe downshifting.... I hadn't heard of synchro-rev but I read about it and it sounds like it would be pretty fun in a car, or bike I guess! But screw the DSG, the synchro whatever, CVTs (continuously variable transmission), and the whole transmission altogether, plus clutches, torque converters, intricate valve trains, catalytic converters, and fuel injection systems... all a bunch of complicated expensive solutions to overcome the inherent flaws in combustion engines. And after all that, you still need a battery and an electric motor to bring the engine to life in the first place. People have gotten so used to these things that they take for granted how complicated it all is. And despite all the expensive and complicated emissions ######, they still end up causing smog in every city around the world. Electric engine: Attach engine to rear wheel with chain and sprockets, twist throttle to go! Max torque from zero rpms! Wheelie machine! No clutch, no shifting. Totally off-topic but just say'n, my little rant, hehe. Where is that magic battery. Getting kinda close - my daily commuter car has a CVT transmission and runs on natural gas, incredibly inexpensive to run, and ultra clean burning, so no smog and no crud in the engine, either. Oh, and I can drive it on the carpool lane. Heck of a deal and apparently a well-kept secret. (To your point, it certainly requires a lot less maintenance than those two-wheel chain-driven tire-shredding rockets in my garage. )
  21. Wow, good luck with that. I'm starting to think it takes a lot more than a year to learn suspension! It's like pulling a thread on a sweater, you just keep finding out there is more to it, and more to it, and more to it...
  22. What a fantastic post! I think I'm going to print this out and take it with me to track days. It is really, really easy to get caught up in trying to push yourself to improve entry speed and it sure can be a frustrating experience, and your post clarifies that extremely well. Recently a riding buddy of mine got really focused on entry and although he didn't realize it, he slowed WAY, WAY down. He thought he was really pushing himself, and he WAS going into the corners faster than me but suddenly I was blowing him away on laptimes, because he was losing so much on his midcorner and exit. It was a great learning experience for me to watch it happen to HIM, because when it happens to ME I am so aggravated that I can't learn a damn thing. Being able to observe it dispassionately was very enlightening!
  23. H, It isn't the full 400+ lbs of weight that one has to hold. We are talking the times a rider has saved it, when it has just gone over the edge of traction, but the tires are still in contact with the ground. How much does one have to "hold" a correctly set up bike, when it is in the turn, and the bike is moving? AND let's not forget no lean angle change (otherwise the rider would have some pressure on the bars). Any of the physics guys up here have a an idea of how to calculate this? CF I don't know how to calculate it, but couldn't you put a sensor on the slide bike, and see how much pressure is being put on the outrigger wheel when it touches down? That outrigger wheel saves slides, right? (or you could measure the amount the outrigger shock travels, and calculate it from that.) Seems like the same principle, it just adds a little upward force on the bike to stop it from leaning over any farther, and that combined with good throttle control can save the slide, right? The outrigger wheel seems a reasonable approximation to a knee slider, since knee sliders do slide easily and I'm sure that little wheel has significant drag, probably would be pretty close to the same amount of friction. Or, how about this, can you gutsy fellas experiment by pushing down a tad with your knee while dragging it and see if it changes your lean angle? It sure seems to me like it would NOT take much pressure to change the lean angle, standing the bike up a little and thereby increasing traction. I'm not reliable enough at dragging my knee to try this myself, although I think I've experienced it a few times when my knee touched down unexpectedly, and a little too hard, bouncing the bike up a little.
  24. OK, I'm curious.... how come your avatar photo is in black and white now? You are starting to look a little... out of date!
  25. Do you find it easy to look over your shoulder, when it's facing the wrong direction, i.e. into towards the bike, and away from where you're actually going. Seems pretty sub optimal to me. There are other reasons why these riders do this, but I'm not going to go into it on here. You'll find all that out if you do level 2 and get on the lean bike, and do level 3 physical drills. Bullet I'm a bit curious about the other reasons, would you mind going into that a bit more? I'm guessing that fear of leaning can make someone want to keep head or body more 'on top of' the bike, and also that hanging your butt off too far can make you get crossed up, any other reasons? I am fighting a tendency to stiffen up my left shoulder and push it forward on left hand turns, and I can't figure out what's causing it. I'm not afraid of leaning it, and I don't hang off very far - in fact I still stiffen that shoulder even when I don't hang my butt off at all. My position is OK approaching the turn, and stays OK when I get into a hang off position, but at the moment I turn the bike, I throw my shoulder forward. It's worse on downhill turns. I am right-handed, and do a lot of my steering, even on left turns, with my right hand, especially at slow speeds. When I sit on a bike on a stand, my position looks fine, and it looks OK on the lean bike too, but when a coach follows me on track they see me make a weird change in position right at the turn-in - sometimes it looks like a late look-in because my shoulder comes forward relative to my head, which sort of looks like I turned my head. Anything you can do to help would be MUCH appreciated!!
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