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Trail Braking

winders said:
I fairly confident that I carry more cornerspeed than you do so my lean angles are at least as severe. So my experience in control should be useful to this conversation.
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Uh-oh, out come the penises, who's got the tape measure? ;) You do indeed lap quicker than me, but I seriously doubt you carry any more speed through T7. :p

Scott, why do you seem unwilling to concede that it is possible to do what I describe, and seem certain that people who have much larger penises then either of us ever will must be wrong? I'm quite willing to concede that I don't understand all the physics, even though I've studied this stuff and have a pretty strong background to apply to it, but I'm also quite certain that you do not either (for instance, by saying "Since the contact patch is below the center of mass of the bike, the bike MUST rotate to the right", you seem to be arguing the "steering out from under" theory of countersteering, which is simplistic and ignores critical torques from camber, gyroscopic effects, and gravity). In the absence of a theoretical understanding of all the dynamics, one must rely on experimentation - GO TRY IT! Have you ever ridden a dirt bike and turned the wheel in while using the rear brake? Same deal. I'm done.;)

Will, many bikes are neutral, especially near vertical, but that's not generally true at larger lean angles - it's difficult to actually test (who wants to take both hands off the bars while dragging knee pucks, assuming their bike has a cruise-control of some kind?), but the difference shows in people's perception of how the bike steers. A bike that feels "tippy" probably requires constant force on the inside bar, and will tend to turn in more if you were to let go of the bars completely - a bike that "doesn't want to hold a tight line" probably requires the opposite torque. And since it depends on the trail, which depends on whether you're braking or accelerating, a bike can feel quite neutral while on the gas but "tippy" on the brakes (the ZX6R that I rode at CSS a few years ago was like this), or feel like it wants to run wide on the gas but feel quite sweet on the brakes (my duc is like this with it's current setup, and so was the 600RR I rode this week) . Bikes sure are cool and complicated beasts!:thumbup
 
Jeff,

You might want to read Chapter 4 of Tony Foale's book "Motorcycle Handling and Chassis Design".

He concludes that gyroscopic or precessional forces have little effect on roll torque but a large effect on steering torque. Steering torque being the effort required to turn the bars. This is why it easier to turn a bike if you fit it with lighter wheels.

He also concludes that tire torque and gravitational forces effectively cancel each other out.

Tony Foale talks a lot about countersteering and no where does he make any statements that agree with your argument.

I didn't come up with my ideas on this without reading a lot on the subject. All the testing I have done shows me that anytime you push on the outside bar, no matter how slowly, the bike will not turn in any more. The bike will, in fact, start to stand up. How much depends on how long and how hard you push on the outside bar.

Scott

P.S. I brought up the corner speed issue to show that my lean angles are at least as severe as yours. Who is faster is not relevant.
 
Will, many bikes are neutral, especially near vertical, but that's not generally true at larger lean angles - it's difficult to actually test (who wants to take both hands off the bars while dragging knee pucks, assuming their bike has a cruise-control of some kind?), but the difference shows in people's perception of how the bike steers. A bike that feels "tippy" probably requires constant force on the inside bar, and will tend to turn in more if you were to let go of the bars completely - a bike that "doesn't want to hold a tight line" probably requires the opposite torque. And since it depends on the trail, which depends on whether you're braking or accelerating, a bike can feel quite neutral while on the gas but "tippy" on the brakes (the ZX6R that I rode at CSS a few years ago was like this), or feel like it wants to run wide on the gas but feel quite sweet on the brakes (my duc is like this with it's current setup, and so was the 600RR I rode this week) . Bikes sure are cool and complicated beasts!:thumbup [/B][/QUOTE]

You seem to be overlooking one thing, Set-up. Every bike a sweet spot in the ride heights that will produce a neutral handling bike, you can change it one way or the other to suit the riders preference. The point is any bike can be tuned into a neutral handling, though most are either right on or vary close to it stock. As far as what lean angle im talking about that would usually be when something drags. At no point have I considered a lean angle less than max in what I have been talking about.

I don’t need telemetry to know if I need to hold the bars or not. If I need to put any pressure on the bars in a corner im all over the bike to find out why. The biggest reason to need to hold a bike down is tire pressure, ride heights, or not being secure on the bike and using the bars to hold onto the bike.

My first race this year was the Toyota 200 weekend. I ran qualifying on Friday, practice and three races on Saturday, practice and the 200 on Sunday. All this and no blisters on my hands the first weekend on my bike. The bike wasn’t set up yet and now I have lowered the front and raised the rear from where it was over 10mm on both. The bike didn’t turn the way I wanted and I had to pull my turn points back and ride around the way it turned. The whole point is I have changed it a significant amount and though it’s better at no time did I need to hold it in. I can release the bars after it’s turned then and now.
Doesn’t seem to fit your model does it?
Will
 
balistic said:
You seem to be overlooking one thing, Set-up... I don’t need telemetry to know if I need to hold the bars or not. If I need to put any pressure on the bars in a corner im all over the bike to find out why.
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No, I'm not overlooking setup, you can change the handling characteristics by changing the tires or playing with the geometry, I do this too - which is why I said the "neutrality" of the bike depends on the tires and geometry several posts ago. I think we're basically agreeing here, Will ;) My only point was that a blanket statement "all bikes are neutral and continue to track when you let go of the bars" isn't quite true, as I think you will agree - no normal bike can work that way at *all* lean angles, or at any particular lean angle at *all* throttle/brake settings (because these change the trail, same as changing the ride height). No bike I've ever ridden is totally neutral all the time.

What I've found on my duc is that it's not possible to get a neutral steering reaction at large lean angles without compromising straight-line stability - your results may vary, and so might mine with a different front tire or suspension parts - so I've erred on the side of stability and live with the added steering torque whilst cranked over, which I don't even notice once I'm used to it.
 
JeffKoch said:
No, I'm not overlooking setup, you can change the handling characteristics by changing the tires or playing with the geometry, I do this too - which is why I said the "neutrality" of the bike depends on the tires and geometry several posts ago. I think we're basically agreeing here, Will ;) My only point was that a blanket statement "all bikes are neutral and continue to track when you let go of the bars" isn't quite true, as I think you will agree - no normal bike can work that way at *all* lean angles, or at any particular lean angle at *all* throttle/brake settings (because these change the trail, same as changing the ride height). No bike I've ever ridden is totally neutral all the time.

What I've found on my duc is that it's not possible to get a neutral steering reaction at large lean angles without compromising straight-line stability - your results may vary, and so might mine with a different front tire or suspension parts - so I've erred on the side of stability and live with the added steering torque whilst cranked over, which I don't even notice once I'm used to it.
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OK Jeff I get the difference in what we are saying. You are speaking in an absolute and what im talking about is much broader. The reason the sweet spot is so hard to find is that the area the bike will work good is so broad, it's not a razors edge like a 70s two stroke more like a new litter bikes power band. I have a tendency to figure out what the bike wants and do that. Also I don't consider different lean angles in my posts, just max lean. I do ride a ZX9 and concours to work over the crest and both bikes are neutral to me at all speeds, good tires, good pressure, early throttle, I can't explain why I don't feel the same differences you do at different lean angles.
Will
 
Seriously, I used to "blip" down the gears then I got lazy. Then I race 2-strokes then I learned to "slip" the clutch through there was no engine breaking on them 2-strokes, I learned to slip the clutch. :toothless
 
Outta Control said:
Seriously, I used to "blip" down the gears then I got lazy. Then I race 2-strokes then I learned to "slip" the clutch through there was no engine breaking on them 2-strokes, I learned to slip the clutch. :toothless
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What im trying to figure out is does trail braking and backing it in go hand in hand? Is there something about having the rear sliding that makes trail braking easier?
The only time I have backed it in was because I was leaned over a little in the brakes and the rear was light, never from dragging the clutch or the rear brake. And I felt like I needed to get it back in track before I turned, but I see guys striping the turn entry occasionally.
Will
 
Trail braking and backing it in are two different things.....I use trail braking more than anything to shave off speed, and settle the front suspension, the bike will turn in faster/easier if the forks are compressed.....I have nothing to add about backing it in....you can ask CTS488, he does a nice little show in t14 @ thunder...
 
Outta Control said:
I agree with Jnglst. Those are two different events.

:toothless
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I know they are different and don't need to done together. I was just looking to see if the trail brake guys and the back it in guys were the same crowd. I remember seeing Tommy and Nicky in turn six at Mid-O and they were both hung out well into the turn, and both still on the front brake.
Will
 
Backing it in is more of a style to 'square' off the turn....

and I wouldn't use the term "trail brake guys," as no doubt any road racer trail brakes into a turn....so I'm a bit confused on what you are looking for. Do you know the purpose of trail braking?
 
balistic said:
I was just looking to see if the trail brake guys and the back it in guys were the same crowd.
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Not in my case, anyway - but I've watched guys backing it in up close, and from what I've seen they're generally on the front brake and slipping the clutch. I haven't yet summoned the testicular fortitude to try this on a roadrace bike, but I've played with it on my XR200 around the Stockton SM track.:teeth

A guy I was talking to ice-races in Canada, and he told me that those bikes start backing around immediately when you drop the throttle going into a turn, at which point you immediately get back on the gas to control the slide, like some of the LeMans go-karts. He basically never used his brakes.:wow
 
JnglstTICAL said:
Backing it in is more of a style to 'square' off the turn....

and I wouldn't use the term "trail brake guys," as no doubt any road racer trail brakes into a turn....so I'm a bit confused on what you are looking for. Do you know the purpose of trail braking?
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The reason I asked it that way is with trail braking you have already lessened the arc of the turn and to square it off would seem to be the logical next step.
I realize trail brakers range from those who can do it to those who can't do without it. My question is just are the guys who are dragging the clutch and backing it also trail braking?
Will
 
Pardon the newb interuption, I'm looking for a little vocabulary clarification on this thread.

Backing it in: sliding the rear wheel coming into/out of a corner (?)

Trail Braking: braking before a turn and then progressively letting them off as you corner (?)

Blipping I know, but I don't know about "slipping." Any clarification is appreciated.
 
self said:
Pardon the newb interuption, I'm looking for a little vocabulary clarification on this thread.

Backing it in: sliding the rear wheel coming into/out of a corner (?)

Trail Braking: braking before a turn and then progressively letting them off as you corner (?)

Blipping I know, but I don't know about "slipping." Any clarification is appreciated.
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Backing it in: anything you do to get the rear to slide before the throttle is turned on. Rear brake, slipping the clutch after a downshift to get the engine spinning up.

Trail Braking: Is letting off the front brake slowly as you turn, replacing the some of the brake load with cornering force, and adjusting your speed late into the corner. a good passing tool.

Slipping is what you do with the clutch after you have done any number of downshifts without blipping. The engine will slow to near idle and then you have to get it back up to road speed by slipping the clutch.
Will
 
newbie here to trail breaking

are there any gotcha's to breaking in the turn with linked breaks?
 
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