[dsn_klr650] nklr - klr riders who have served or are servi

[Alan L Henderson]

matteeanne@... wrote:

> Look, turn, dont turn, enough of the freekin turning > already, move on! (while turning or not) Knee's no > knee's standing sitting, hands free, but freekin turn! > Sheesh!

And so we have shown, without a doubt, that the physics of turning a motorcycle is a very complex subject. Maybe we should talk about the fact that braided brake lines don't increase braking force unless you could pull the brake lever all the way to the bars with the stock lines. Alan Henderson A13 Iowa

[Don Van Dyke]

At 07:24 AM 12/15/2004 -0600, Alan L Henderson wrote:

>Maybe we should talk about the fact that braided brake lines don't >increase braking force unless you could pull the brake lever all the way >to the bars with the stock lines.

Wicked sense of humor Don Van Dyke Sacramento, California Moto@... www.intellection.org

[scttotis]

That's a good one. When in the air, if you turn the wheel to the right, what does the bike do? I am going to build a mc model with 2 toy gyros and steer with a radio control servo, when I get the chance. I'll video it and post it. I noticed watching a motocross high jump event that just before they got to the bar, they would apply the rear brake and stop the rear wheel, and that would rotate the bike over the bar from nose high to nose low.

--- In DSN_klr650@yahoogroups.com, kdxkawboy@a... wrote: > In a message dated 2004-12-14 10:12:21 AM Pacific Standard Time, > k.saltzer@c... writes: > > > > > > > I believe that when I counter steer to the left, to turn right, I am > > turning the bars, which causes the forks above the front axle to > > twist the very stable gyroscopic loaded front wheel to turn to the > > left, making it momentarily unstable, (as noticed when you go over a > > bump while putting a countersteering moment into the bars) and causes > > it to move to the left also, which is then followed by the rear tire, > > and then the bike begins to lean over and turn to the right. I start > > off my turns by pushing down on my left footpet to gain a very stable > > tripod position which allows me to use more strength to turn the bars > > quicker, and it gives me a firmly planted place to hold my body mass > > right where it was when I was going straight. > > > > > > I good way to demonstrate those gyroscopic forces is to do a classic pancake > jump. As the bike runs up the face of the jump you countersteer it into a turn > and as the bike leaves the earth you keep applying the countersteer the > gyroscopes pull you into a lean with the rear tire swinging higher than the front > (at least that is what it feel like as I've only ever seen Guy Cooper really > achieve a nose down attitude) and as you spot your landing you push the high > bar to straighten the bike upright. A pancake jump is very much like hitting a > sharp high banked turn without the banking. > > Pat > G'ville, Nv > > > [Non-text portions of this message have been removed]

[scttotis]

> First off the counter steer movement is ever so slight. I buddy of

mine and I

> tried to set up a transducer to measure the deflection of the triple

tree

> from dead ahead, recording the readout on a portable PC and found we

had to set

> our full scale range to just a couple of degrees to have the

resolution to make

> our measurements. We also discovered that during the turn the rider

made a

> lot of subtle adjustments, pushing on the inside bar to tighten the

arc and

> pushing on the outside bar to straighten out or hold a constant arc

- you don't

> really turn into the turn as much as countersteer out of the turn to

maintain an

> arc. Also learned that the slower you went the more deflection that was > required to initiate the turn, which leads me to believe that the

amount of

> countersteering movement required to start a turn is inversely

proportional to the

> amount of centrifugal force generated by the front wheel. >

Respectfully, I think this conclusion is not valid based on your observation. Another explaination is this: At higher speeds, a lesser deflection of steering is observed because the required tirepatch offtracking to the side(as noted by Keith in pothole avoidance) given a time period of say one second, occurs with decreasing deflection as speed increases. The gyroscopic explaination for stability is only partial. A bicycle at 1mph has better stability than one at 1/2 mph, and that is not due to gyro forces. It is due to the fact that steering deflections at higher speeds allow the rider to quickly correct to get the mass of the rider and bike balanced by moving the tire patches around underneath. The proof of this is the Ice skater on one skate. At speed no problem, but she will fall over eventually as she slows down and can no longer course correct with her skate to maintain her balance. No gyro action there.

[scttotis]

Eric, I looked back a ways and did not find the reference to camber thrust as the turning mechanism for morotcycles. Can you re post that link? I am only concerned about camber thrust. Thanks, Scott . --- In DSN_klr650@yahoogroups.com, "Eric L. Green" wrote:

> On Tue, 14 Dec 2004, John Kokola wrote: > > --- In DSN_klr650@yahoogroups.com, "klr250not"

wrote:

> > > Countersteering is turning the front wheel in the opposite

direction

> > > of the turn and the lean. You'll see sportbike racers doing

this as

> > > they round curves as high speed. In a right turn, for example, the > > > rider'll be leaned over so far to the right that their right knee > > > will be skimming the pavement. At the same time, the front tire > > > will be pointed maybe 20 degrees to the left as it would be if > > > making a left turn at very low speed. > > > You'll only see this (whether on pavement or on dirt) when the

rear tire

> > is stepping out -- i.e. in a 'loss of traction' situation. > > No, you will see it *ANY* time that camber thrust (the desire of the

tire

> to turn in a circle around the point where the line through its

front axle

> hits the ground) at a given lean angle necessary for balance

exceeds the

> amount of thrust needed to maintain the angular velocity desired

(whether

> that is a turn or going straight). Thus it mostly only happens with > smaller front wheels (where the line hits the ground fairly close to the > tire), and you'll rarely see it happen to a visible extent on the

KLR with

> its big honkin' 21" front wheel unless you're offroad and having a

lot of

> slipping going on. > > But you can still see this scenario in action on the KLR. It can happen > when you're going down the freeway, even, if there happens to be a

strong

> crosswind -- lean over left into the wind (it'll happen

automatically due

> to a combination of gyroscopic procession and the steering geometry of > your front fork), and you'll notice your front wheel pointing right,

while

> the bike is leaning left and going straight down the freeway! What's > happening is that the scrub produced by the rightward-pointing tire is > offsetting the camber thrust produced by the leftward-leaning tire (yes, > they're one and the same tire so that the tire goes straight even > though it appears that the bike should be turning right! > > Sport bikes with their tiny front wheels generate a LOT of camber thrust > when leaned only slight amounts -- enough camber thrust that at high > speeds it would cause the rider to be thrown off the outside of the bike > due to inertia unless the rider hit the bar harder than necessary to

make

> the turn in order to lean over farther due to gyroscopic procession such > that the outward force gets carried down to the ground through the > centerline of the bike. Thus at high speeds the front wheel ends up > pointing towards the OUTSIDE of the turn in order to offset the

amount of

> camber thrust generated by a lean necessary to maintain balance at the > given speed and corner. Here's a few pictures of race bikes making

corners

> with their wheels pointed "the wrong way" (or at least straight): > > http://www.flexi-glass.com/Clint_McBain.jpg > http://www.motorcycle.com/mo/mcmail/nasb/mcphotos/race1.jpg >

http://www.bikersweb.co.uk/racing/wsb2002/BRANDS%20HATCH/287wsb_bayliss.jpg

> > Do note that: a) by hanging off the bike to the inside (thus why road > racers are hunched on their bikes like defecating chimpanzees, so

they can

> hang off the side as needed), you reduce the amount of lean needed to > maintain balance while cornering a given curve, and thus the amount of > slip angle needed to produce enough outside scrub offset the inside

camber

> thrust produced by the lean. Ideally for maximum performance you

want *no*

> slip angle (or as little as possible, anyhow), because this minimizes > frictional losses. b) The tire and bike geometry should be set up as > "neutral" as possible, so that at a given lean angle needed to maintain > balance through the most common turns in a course, the curve followed by > the tire should be close to what would normally be produced by the conic > section through the axle of the wheel (thus less need for using tire

scrub

> to offset camber thrust). > > In reality, b) conflicts with another desire -- the desire to be able to > change direction rapidly -- which calls for using small wheels that > produce lots of camber thrust (for rapid directional changes) and

minimize

> the gyroscopic effect that wants the wheel to go straight -- but in > current road racing you'll still see neutral handling a good

percentage of

> the time due to the rider's ability to hang off (due to the > constipated-chimpanzee riding position), and, at slower speeds, even > *negative* slip angles (where the tire is pointing along the

direction of

> travel) when the lean necessary to balance the bike does not provide > sufficient camber thrust to make the turn at the desired pace.

Needless to

> say race bikes are quite a bit twitchier than is desirable for stability > on the highway! > > -E

[scttotis]

I found my own reference re camber thrust. That this can be a dominant turning force, in fact the reason a motorcycle turns and which requires an in turn countersteer on a 21 inch MC tire is hard to buy at this point, but I am going to study it with an open mind. My fundamental problem with the tapered can theory is that your turning radius would depend on the taper, and that would be fixed by the geometry of the tire and the amount of lean. If that is so then shifting your weight to the inside of the turn would increase your turning radius because the bike doesn't lean as much , and we all know that a rider with weight shifted to the inside doesn't have to lean the bike as far to scribe the same radius at a given speed as a rider that does not shift his weight . Scott http://www.geocities.com/siliconvalley/vista/8129/tip048.htm

--- In DSN_klr650@yahoogroups.com, "scttotis" wrote: > > Eric, I looked back a ways and did not find the reference to camber > thrust as the turning mechanism for morotcycles. Can you re post that > link? I am only concerned about camber thrust. Thanks, Scott . > > > > > --- In DSN_klr650@yahoogroups.com, "Eric L. Green" > wrote: > > On Tue, 14 Dec 2004, John Kokola wrote: > > > --- In DSN_klr650@yahoogroups.com, "klr250not" > wrote: > > > > Countersteering is turning the front wheel in the opposite > direction > > > > of the turn and the lean. You'll see sportbike racers doing > this as > > > > they round curves as high speed. In a right turn, for example, the > > > > rider'll be leaned over so far to the right that their right knee > > > > will be skimming the pavement. At the same time, the front tire > > > > will be pointed maybe 20 degrees to the left as it would be if > > > > making a left turn at very low speed. > > > > > You'll only see this (whether on pavement or on dirt) when the > rear tire > > > is stepping out -- i.e. in a 'loss of traction' situation. > > > > No, you will see it *ANY* time that camber thrust (the desire of the > tire > > to turn in a circle around the point where the line through its > front axle > > hits the ground) at a given lean angle necessary for balance > exceeds the > > amount of thrust needed to maintain the angular velocity desired > (whether > > that is a turn or going straight). Thus it mostly only happens with > > smaller front wheels (where the line hits the ground fairly close to the > > tire), and you'll rarely see it happen to a visible extent on the > KLR with > > its big honkin' 21" front wheel unless you're offroad and having a > lot of > > slipping going on. > > > > But you can still see this scenario in action on the KLR. It can happen > > when you're going down the freeway, even, if there happens to be a > strong > > crosswind -- lean over left into the wind (it'll happen > automatically due > > to a combination of gyroscopic procession and the steering geometry of > > your front fork), and you'll notice your front wheel pointing right, > while > > the bike is leaning left and going straight down the freeway! What's > > happening is that the scrub produced by the rightward-pointing tire is > > offsetting the camber thrust produced by the leftward-leaning tire (yes, > > they're one and the same tire so that the tire goes straight even > > though it appears that the bike should be turning right! > > > > Sport bikes with their tiny front wheels generate a LOT of camber thrust > > when leaned only slight amounts -- enough camber thrust that at high > > speeds it would cause the rider to be thrown off the outside of the bike > > due to inertia unless the rider hit the bar harder than necessary to > make > > the turn in order to lean over farther due to gyroscopic procession such > > that the outward force gets carried down to the ground through the > > centerline of the bike. Thus at high speeds the front wheel ends up > > pointing towards the OUTSIDE of the turn in order to offset the > amount of > > camber thrust generated by a lean necessary to maintain balance at the > > given speed and corner. Here's a few pictures of race bikes making > corners > > with their wheels pointed "the wrong way" (or at least straight): > > > > http://www.flexi-glass.com/Clint_McBain.jpg > > http://www.motorcycle.com/mo/mcmail/nasb/mcphotos/race1.jpg > > > http://www.bikersweb.co.uk/racing/wsb2002/BRANDS%20HATCH/287wsb_bayliss.jpg > > > > Do note that: a) by hanging off the bike to the inside (thus why road > > racers are hunched on their bikes like defecating chimpanzees, so > they can > > hang off the side as needed), you reduce the amount of lean needed to > > maintain balance while cornering a given curve, and thus the amount of > > slip angle needed to produce enough outside scrub offset the inside > camber > > thrust produced by the lean. Ideally for maximum performance you > want *no* > > slip angle (or as little as possible, anyhow), because this minimizes > > frictional losses. b) The tire and bike geometry should be set up as > > "neutral" as possible, so that at a given lean angle needed to maintain > > balance through the most common turns in a course, the curve followed by > > the tire should be close to what would normally be produced by the conic > > section through the axle of the wheel (thus less need for using tire > scrub > > to offset camber thrust). > > > > In reality, b) conflicts with another desire -- the desire to be able to > > change direction rapidly -- which calls for using small wheels that > > produce lots of camber thrust (for rapid directional changes) and > minimize > > the gyroscopic effect that wants the wheel to go straight -- but in > > current road racing you'll still see neutral handling a good > percentage of > > the time due to the rider's ability to hang off (due to the > > constipated-chimpanzee riding position), and, at slower speeds, even > > *negative* slip angles (where the tire is pointing along the > direction of > > travel) when the lean necessary to balance the bike does not provide > > sufficient camber thrust to make the turn at the desired pace. > Needless to > > say race bikes are quite a bit twitchier than is desirable for stability > > on the highway! > > > > -E

[Roy]

US Navy ETN2 1957-1961 USS Beatty DD756 Roy Cope