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racer

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Posts posted by racer

  2. Basic Riding/cornering Technique

    in Cornering and Techniques

    Posted

    Ok... let me be perfectly clear...

     

    In my opinion, there should be no words or thoughts of a psuedo-verbal nature running in your mind while riding. Nor should you be trying to concentrate on the order of your "to do list" of stuff to remember to not forget... just focus on doing the riding.

     

    Pick a turn point and hit it. Dont think about anything else until you can do that without trying. Then add another goal. Focus on one goal or sub-product... and then the next one. Then the next one...

     

    Don't think about anything while riding. Don't worry about anything. Don't critique anything... until after you are done riding that section. Then relax and close your eyes and do it again in your mind... with pictures. No words.

  4. Effect Of Hanging Off

    in Cornering and Techniques

    Posted

    In any case, we need to be careful about how we define "higher" and "lower" wrt c/g.

     

    If the c/g is higher or lower in line with the centerline of the bike, it makes no difference to lean angle at a given speed per se. However, moving the upper body off the bike (inward, long and low) moves the c/g significantly forward as well as inward putting weight on the front which is what is going on with the "hook turn", I believe.

  6. Basic Riding/cornering Technique

    in Cornering and Techniques

    Posted

    This is what's going through my head as I ride (I keep reminding myself about this stuff all the time):

     

    Basic riding technique:

    1. Relaxed on the bars (the "death grip" will/may cause headshakes and all sorts of bad things)

    2. Distribute some weight onto the pegs (as an "extra suspension", helps keeping the bike stabilized)

    3. Torso leaned forward, loose elbows, forearms parallell with the street (reduces wind drag, helps staying relaxed on the bars, more leverage for steering)

    4. "Widescreen" attention. Continously scanning the environment, yet trying not to narrow my attention by "hunting" with my vision.

     

    Cornering technique: (the 4 points mentioned above still apply)

    1. Get the body into position (a little off the saddle, upper body parallell with tank, more weight transferred onto the pegs)

    2. Identify the corner entry point and point the bike in it's direction.

    3. Roll off throttle and start braking (smooth transitions). Make sure I'm in the correct gear for the corner.

    4. As I'm closing in on the turn entry point, I look further into the corner and decide on a line (and the apex, if it's visible from where I'm at).

    5. I get off the brakes in time to let the suspension stabilized itself before the actual turn-in. I'm now coasting towards the entry point.

    6. As my front wheel passes the turn entry point, I steer the bike (as quickly as I can) to get it pointed to where I'm looking, using my outside peg as the main pivot point.

    7. Crack open the throttle as quickly as possible and get close to a 60/40 weight distribution. (WOW, this really makes the bike work!)

    8. Relax. Breathe. :)

    9. As I approach the apex, I look further ahead and find my exit point.

    10. Gradually increase throttle as the bike stands up. Look towards the next turn and get ready start over again.

     

    To sum it up, I'm working on getting that "hook turn" and "two step" technique working to the point where I don't need to spend too much attention on it.

     

    Am I forgetting something? Am I concentrating on too many things at once? Am I going too fast? Is the bike unsuitable for this riding style (CBR1100XX)? Or should I just keep on practicing the same way?

    Well... that IS a lot of stuff to be "going through your head as you ride". Maybe try working on one thing at a time and maybe try not to "think" too much while riding? Maybe try to do your "thinking" before you ride and then try to relax and be in the moment so to speak while riding?

     

     

    My problem:

    I keep blowing corner entries, and I keep triggering those SR's (in too fast? too much lean? good enough traction? going wide?), which mainly result in several mid turn corrections (both throttle and steering inputs). It's not like I toatlly panic or anything (I'm going too slow for that), but my instincts are telling me to slow down or stare at that manhole I want to avoid, allthough the rational part of my brain tells me that I should stay on the throttle and look where I want the bike to go - and 8 times out of 10, my instincts win the battle. Everytime I blow an entry (and most likely the entire corner), I just want to bitchslap myself.. :)

    Relax and don't be so hard on yourself. Nobody is perfect and nobody gets it right the first time. And nobody gets it ALL right ALL the time. Chill out and try to work on one technique at a time. I'd go with getting your reference points on a road you ride frequently and choose a turn point. And then work on hitting that and your other sub-products at a speed that doesn't set off your SR's. Speed will come later with proficiency.

     

    racer

  7. I Keep Washing My Front End

    in Cornering and Techniques

    Posted

    Are you trailbraking?

     

    What do you mean, "before the wheel rebounds?" Why would the wheel be rebounding? Do you mean before the radial tire "sets"?

     

    Weighting one peg as opposed to another does essentially nothing. I wonder what else you might be doing when weighting the inside peg.

     

    If you are "locked on" with your outside leg before you turn in and using that for your pivot point, isn't your weight there? Or at least half of it? I mean, how do you weight the inside peg if you are really locked on with the outside leg?

  11. Setting Sag

    in School Questions/General Discussion

    Posted

    how do you know when the springs are too soft for you body weight?

     

    Springs are rated and manufacturers will sometimes publish a chart of weight range(s) and spring rates for their machines in the owner's manuals and/or service manuals. Especially for racing type motorcycles or factory roadracers. (Any suspension professional should also have access to prepared specifications for each machine.) Due to unique suspension design spec's, spring specifications may not translate from one machine to another, ie. the same spring rate for the same weight range from one machine to another. (The best spring for you on a ZX6 might not be the best spring for you on an Ohlins equipped Yamaha R6.)

     

    Manufacturers generally install a spring for the average rider, say 150-160 lbs. If you are more than about 25-30 lbs above or below that, you probably would benefit from a different spring. Like if you weigh less than 125 lbs or more than 185 lbs. That's a very ballpark figure and I suggest you pose your question on a website dedicated to suspension tuning. I don't have time to Google up answers for you right now. Try Tony Foale or Max McCallister at Traxxion Dynamics.

     

    That said, a professional international level superbike racer/tuner told me his "rule of thumb" was that the proper rear shock spring (rate) will require zero or near zero pre-load to achieve the proper or desired sag at the rear shock. I'd say that, in general, the less pre-load you need to add to put yourself in the middle of the fork/shock's travel, the more spring you are using effectively and the better off you will be. I participated in a good thread about suspension here not too long ago with harnois, et al. I'll try to find it when I have more time.

     

    The nutshell bottom line... if you are bottoming out your suspension under spirited riding or need to max your damping adjusters to stop the wallowing, you probably need heavier springs. If you set the damping at zero and the suspension feels like a rock and the bike slides like crazy because it won't absorb bumps... probably too stiff. :P

  12. Rear Suspension And Gas

    in School Questions/General Discussion

    Posted

    Thanks for the input, racer :)

     

    I have no doubts that the rear will tend to rise when putting the front wheel against a wall due to the angle of the swingarm. But won't the weight transfer front-to-rear whilst accelerating "cancel out" or even "override" this effect?

     

    Hi Leftlaner,

     

    If you think about how much power is on tap and being applied to the rear wheel/swingarm by the engine (enough to propel the total mass of the bike and rider forward with a high degree of force/acceleration approaching 1G) and then consider the amount of weight at the rear suspension is but a fraction of that, even if the suspension doesn't physically extend or become solid (like a hard tail) at lower acceleration, clearly there is enough force applied to resist compression to some degree and effectively "stiffen" the rear suspension proportional to the amount of throttle/acceleration.

     

    Make sense?

     

    racer

  13. Trail Braking---not That Fastest Way, But They All Do It

    in Cornering and Techniques

    Posted

    ...

    Yes it does. But... could that be because you "still steer relatively slow"? Turn-in and cornering force will compress your suspension far more than braking (attach a zip-tie to your fork leg if you wish to test this theory). Can timing your turn-in at the moment of brake release accomplish the same thing?

    ...

    I'd consider your proposal as a form of trail breaking as well. Timing the release of the breaks such that the turn-in point happens after the release but just before the front offloads is a delicate task, and IMHO not easier than the technique I've described. Basically, if I understand you correctly, what you suggest is more or less what I've described, but refined for better result and which requires better control and timing.

     

    No. Not at all. Trailbraking is defined as continuing to brake during and after turn-in.

     

    It was not my intention to recommend a specific technique in the paragraph of mine you quote above. I was thinking about and asking question(s) about what Carl suggested Keith has written wrt to timing turn-in after releasing the brake and before the suspension can rebound, ie. considering it might essentially be using cornering force itself to counter the rise of the front suspension after coming off the brake.

     

    Also, I was asking you to consider if "still steering relatively slow" might be a part of the issue wrt relying on the brakes to do something other than slow down. For instance, while it takes the average street rider about one second or even more to lean a motorcycle into a turn, a fast rider does it in about one quarter of a second. Not much braking gets done in a quarter of a second, eh?

     

    As I said above, IMO, smoothly letting off the brake lever to control the rise of the front suspension is definitely a valid and useful skill. However, doing it while turning-in is an exceptionally delicate, complex and risky operation when at or near the limit of traction already. While timing your flick as close as possible to your brake release point may seem more "delicate" or more precise than trailbraking to you, trust me, it really isn't. Trailbraking involves balancing several limits at once, while letting off the brake first reduces that number. And it's an inherently less risky proposition that would result in more available traction... which would lead to higher cornering speed, of course.

     

    Please bear in mind I am trying to approach this subject within the parameters of the thread title which questions whether or not trailbraking (as a standard technique for every turn) is the fastest way around a race track. Not what feels easier. And that is a point that Keith covered here (in this thread, I think).

     

    The point: being on the brake feels comforting and reassuring. It gives the rider a way to feel in control of the situation throughout the process. "Easing their way into it...", as Keith said. Feeling the traction each and every millimeter of the way through the brake lever and being able to react by modulating the brake lever to compensate for any impending loss of traction as opposed to relying on their sense of speed and just "throwing it in" and "hoping for the best" with no way out, nothing to do if the front slides... except gas it more! I imagine that the front brake lever and trailbraking may become a very real "security blanket" that many riders resist letting go of.

     

    In any case, how much compression does the fork really need to effectively quicken the steering? And is it possible to achieve that compression without sacrificing traction or potential flick speed the way that trailbraking does? Long and low? Kiss the mirror? Hook turn?

     

    As I said above, rolling off the throttle will compress the suspension and weight the tire enough for flicking all by itself. And changing your body position to alter your center of gravity can amplify that advantage. In my opinon, carrying a higher entry speed while off the gas with the proper body position is more effective and efficient than turning-in and entering on the brakes for most turns.

     

     

    Regarding the rest of your post, there's a good chance you're right about getting first thing first and leaving trail breaking as a more advanced technique to master. So yes, I always listen and try to learn and improve, and putting that kind of entry aside might be the thing to try. Still, and possibly because I'm still far (I think) from flicking the bike fast, it does give me a better feel to keep touching the breaks very lightly on entry.

     

    Exactly. You said it all. It gives you a better feel.

     

     

    I need track time :)

     

    Don't we all!! :P

     

    Get Keith's books and take the schools. There is no substitute.

     

     

    Sincerely,

     

    racer

  14. Rear Suspension And Gas

    in School Questions/General Discussion

    Posted

    Hi Leftlaner,

     

    At first glance, it is very counter-intuitive until you actually look at a chain driven motorcycle and visualize what happens to the rear suspsension when you turn the throttle.

     

    I don't know if your bike is shaft or chain driven; but, if you kneel down low enough to see the chain and the swingarm from the side, you will notice the swingarm is angled downward from the pivot shaft and the upper (pulling) side of the chain is attempting to pull or rotate the swingarm downward when accelerating. Hence, the suspension tries to extend and becomes effectively stiffer under acceleration.

     

    Another test you can perform with your own bike is to put the front wheel against a wall and give it some gas while letting the clutch out a bit. You may find the result interesting.

     

    Check it out. Let us know what you find.

     

    racer

  15. Trail Braking---not That Fastest Way, But They All Do It

    in Cornering and Techniques

    Posted

    ...

    The bottom line is that while being on the brake may steepen the steering angle, it also increases stress on the contact patch reducing traction and, by defnition, dictates a slower entry speed and slower, not quicker, turn-in in with a more shallow entry line. And, in most circumstances, I believe the goal you describe can be accomplished with more efficient techniques that have been discussed at some length here.

     

    racer

     

    IMHO, adding more load to the front wheel doesn't necessarily reduce traction. For maximum *potential* of quick turning, you need as much vertical force on the front as you can apply, to get maximum traction for the fast steering input.

     

    Mmm... not quite.

     

    "For maximum potential of quick turning", you need *some* weight or vertical force on the front wheel. As you allude, when applied with skill, the front brakes are powerful enough to lift the rear off the ground without a loss of traction at the front. Clearly, that is too much vertical force on the front for maximum *potential* quick turning.

     

    Also, the key here is vertical force in that once you begin to lean the bike over, the added lateral force negates the whole "bigger contact patch" deal. If you think through the "bigger contact patch" deal... once you begin to lean the bike, that "vertical force" is no longer vertical and the "bigger contact patch" due to vertical force created by braking shrinks in direct proportion to lean angle.

     

    So, if one is carrying enough speed to be at maximum traction upon quick turn, that is on the verge of sliding or "pushing" the front at the turn point (which is the goal of a really fast rider... by definition, maximum speed), adding brake force/stress on top of the lateral cornering force/stress must reduce traction and dictate a slower speed.... or, obviously, you will lose the front.

     

    Like Carl alluded, once you lean over, being on the brake is a game of diminishing returns.

     

     

    Personally though, although I still steer relatively slow, I do find that keeping the break lever feathered on entry prevents the front from offloading on releasing the break.

     

    Yes it does. But... could that be because you "still steer relatively slow"? Turn-in and cornering force will compress your suspension far more than braking (attach a zip-tie to your fork leg if you wish to test this theory). Can timing your turn-in at the moment of brake release accomplish the same thing?

     

    The other option is break, release, wait for the front to stabilize after possibly offloading it, start turning. With the breaks, it's just break, release 95% of the breaking force while keeping 5% to prevent offloading, start turning while releasing the rest 5%. I might be wrong, but I feel that it saves a lot of time on entry over a technique at which you completely release the breaks before applying the steering input, due to the required stabilization period.

     

    Exactly... "due to the required stablization period". The period of time it takes the suspension to rebound. If you feel that period of time is big enough to cause a slower lap, is it big enough to fill with turn-in force?

     

    And what about using your body to alter COG? Can using your body position to alter your COG and f/r weight distribution in conjunction with a rate of deceleration that is already weighting the front without the brakes create enough weight on the front wheel for a sharp and quick turn in? Don't forget, simply rolling off the gas transfers a significant amount of weight to the front wheel. And, if at the moment you lean into the turn, the cornering force brings you to max traction and you are pushing the front, trailing the brake is a very risky game that takes a lot of attention.

     

    Bottom line, IMHO, if your sense of speed and traction isn't good enough to be confidently pushing the front at will without the brakes as a matter of normal course (*yawn* I slid the front ten feet into that turn *yawn*) or you "still steer relatively slow", using the brakes will, in 90% of the cases, overpower your attention and sense of speed and traction causing SR's and your entry speed to be too slow and your line to be too shallow (on top of an already shallow line due to "still steering relatively slow") ... and THAT is the final point.

     

    IMHO, if you aren't already at the level where you can pretty much push the front at will without the brakes, you aren't really ready to be playing with trailbraking as a standard skill to go faster outside of standard trailbrake situations like a DR turn. You will only slow yourself down, limit your learning curve and stunt the development of your sense of speed and traction.

     

    racer

  16. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    I believe the front end geometry has a lot to do with what goes on at the front and that even at lean angle, the front is "trailing" due to the geometry. And, as you said, if the geometry is set-up or designed well at a "sweet" angle, it will trail in a 'neutral' state that will require no input at the handlebar to maintain lean angle.

     

    So... THAT is one thing. And it needs to be sorted for neutral and/or non-neutral (?) geometry.

     

    The OTHER thing in my mind is what happens a} under acceleration... b} at an equivalent delta v or rate of acceleration at one speed range or another, ie. taking Turn 3 at 50 mph or taking Turn 3 at 65 mph.

     

    And, finally, c} ... in the same way that you experimented at very low speeds and compared them to high speeds, consider speed ranges in between those extremes such as 2bigalow alluded to in his post... and THEN... apply this to different lean angle ranges, ie. minor leaning at low speed driving around town vs major leaning at low speed or bending off on the interstate at 100 mph vs dragging your footpeg through a 100mph sweeper.

  17. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    So I'm out in the garage pushing an upright bicycle at various speeds with the wheel turned in (you've got me crazy now too).

    LOL! :lol:

     

    Welcome to my asylum! Ha ha ha ...

     

    Under throttle with the back wheel exerting it's influence you are taking advantage of that stabilizing swingarm joint which has no vertical hinge to help settle the motorcycle. However, I still think the vertically hinged front with it's turned in (to whatever degree) front wheel and considerable force still going on at the front contact patch, I think that front still has a lot of say about the final arc taken (to whatever degree it is still loaded).

    This is where my logic takes me as well.

     

    Unfortunately I lent my copy of Twist2 to a friend in NH and can't look up the chapter in question. My guess is it refers to a "relative" amount of increased steering influence by the rear wheel ( I vaugly remember parts of the chapter). As an ancient old MotoXer, using weight bias to the rear, so that stiff swingarm joint stabilizes the bike is like breathing air, but it seems to me unless the front is off the ground, there is always some sort of influence from the front. It may be minimized again depending upon the amount of weight shift, but force at the front contact patch is force at the front contact patch I would guess.

    The chapter you refer to does not jump to mind right now. I will search through "my" copy of Twist II tonight for what you are on about here.

  20. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    Hi Carl,

     

    Thank you very much for your input. As you can see, I've been chasing my tail a bit.

     

    First, I didn't know that about cars. That is, that a car would follow a wider arc at a higher speed for the same turn angle of the front wheels... unless it was sliding a bit. For example, I know that a car will "understeer" and "oversteer", but, I thought of understeer as "pushing" the front to some degree, sort of a low level slide as it were where the front doesn't quite track. And oversteer meaning the rear is lighter and tends to come around. I don't know about the traveling further forward for the same amount of turning. I'll have to think about that.

     

     

     

    In addition to that often a bike will steer a small bit into the turn once countersteering in is finished, more so at slower speeds, less at higher speeds, but if the bike is tracking and not sliding there is some amount of front wheel turn in is there not? While the rear may take the bulk of the turning on, I wouldn't be surprised to find the front contributing something. Sure you can wheelie mid turn, but that doesn't mean the front won't contribute a percentage if it's on the ground. It may be following along, but to contribute nothing it would have to be weightless. So perhaps the turned in front wheel also generates a small inward (turning) force as well, which also would be constant in rate, meaning speed would effect what radius arc it helped generate. If the front contributed nothing to cornering you couldn't lose the front in a turn.

     

    Make sense?

     

    Yes, this makes a lot of sense to me. And that is where I began in my own mind before reading the "Steer for the Rear" chapter in Twist of the Wrist II and trying to come at this from that angle so to speak. It just makes logical sense to my mind. I'm going to do a little more research and think about it some more.

     

    Thanks again for adding your perspective.

     

    racer

  22. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    "Everybody knows that the faster you go, the steeper you have to lean to get around a turn. Right? Okay I agree. The more speed you have, the more centrifugal force is generated pushing you to the outside and steering to a steeper lean angle compensates for that force and allows you to hold your line."

     

    ~ Keith Code, A Twist of the Wrist II, page 67

  23. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    Welcome back, tweek!

     

    It sounds like you had a great time. I'm really looking forward to reading your blog.

     

    I can't tell from the video what the "knee to knee" drill is about. What are you trying to do there?

     

    Also, I'm not clear what your symbols mean here: "Lean Angle != Turn Radius". Is the exclamation point like a slash through the equal sign meaning that lean angle does NOT equal turn radius?

     

    Thanks,

     

    racer

  24. Lean Angle == Turn Radius?

    in Cornering and Techniques

    Posted

    Alright, even though there is more cornering force applied to the suspension and at the contact patch, if the bike is accelerating, the suspension actually extends rather than compressing as the chain pulls the swingarm down like a lever forcing the rear to rise. And the front gets light and tries to rise under acceleration as well (the beginning of the wheelie process).

     

    So, the front fork does not compress under acceleration in a corner, even at relatively low acceleration of 60/40 and higher relative cornering forces.

    Upon further consideration, I realize that I don't know this for certain. Can cornering forces "overpower" the tendency for acceleration to extend the (front) suspension? For instance, under mild acceleration rates such as will effect a 60/40 weight distribution, will some level of increased velocity create enough cornering force to balance or even counter-act the lifting effect (at the front) of that relatively mild acceleration?

     

     

    So... the wheelbase gets a tad longer and the fork gets longer so maybe the front wheel turns out due to the geometry ... but the front is still merely trailing under acceleration. The rear wheel is in control.

    Or not?

     

    Is it true that a small amount of force must be applied to the inside bar to maintain lean angle (unless hanging off)?

     

    Would this mean that in fact the front is constantly controlling or affecting lean angle as the bike is attempting to stand up under acceleration?

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