Now before i start this is only what i have observed through riding and doing the superbike schools and reading the twist of the wrist series.My background is in mechanical engineering and i always want to know why is it so.What is the benefit of hanging off a bike,purely from a weight balance point of view.Here goes.When you turn left you first turn the bars right to tip the bike over to the left(countersteering).As the bike starts to lean you then gradually (sometimes unknowingly) turn the bars left to the point that maintains the angle of lean.The bike is in equilibrium for that angle of lean and you can actually take your hands off the bars when the speed is high enough.To turn tighter you would have to be turning the bars more to the left,but for the given lean angle and weight distribution you will just stand the bike up.So you would have to turn right a bit to increase the lean angle before you turn more left to maintain centrifugal weight balance for the new sharper radius.This is because your body weight is fairly high on the bike so you need alot of lean angle to stop it standing the bike up.When you're over the side of the bike and lower down on the inside of the turn,the bikes centre of gravity is dramatically different.Say for a given lean angle of 40degrees and a front wheel angle of 5 degrees into the turn at 80km/hr sitting upright on the bike.If you were to hang off and low,that corner could be taken at say 35 degrees at say 6 degrees front wheel angle at 80km/hr.Even though the bike is more upright with more turning angle on the front wheel because your weight is low and on the side your turning into,the bike won,t stand up.This in turn allows greater corner speed to be acheived at the previous 40 degree lean angle with more front wheel angle because of the new weight disribution,or more ground clearance for the bike at a given speed that this becomes an issue.Staying off the bike coming out of corners also allows you to get on the centre of the tyre sooner and gas out of the corner sooner and harder.My last track day i was a little rusty but going real loose on the inside elbow and digging that ouside knee into the tank forced my body to allow the bike to take its natural(much tighter) turning radius for my body position and given speed.So if you want a busa to turn, get off it,dig the outside knee in and go slack on the inside elbow and it almost turns like a motorbike. Glenn the Spa Man<i></i>
Glenn,
will you all of that in English and a little slower please? My eyes are rolling to the left, my ears to the right and my nuts have gone centripetal!
Bloody engineers, conceptual brilliance buggered by Newton!
Max Madmax - GSX1300R Black and Grey Buses Rule
Good Bike, Good Woman, Good Road, Good Weather, Good God - Good Bye!
Smith and Wesson - The original point and click interface.
Some people are alive only because it's illegal to kill them.
<i></i>
I had to type fast as i was getting dizzy and was about to fall off the chair. Glenn the Spa Man<i></i>
I hang off. Other riders I have seen don't and still go amazingly fast round corners. (Eg Rev)
Lucky he doesn't lean off!!! Lol
But I do believe in the theory above.
Let's face it, it's fact otherwise Gp riders etc wouldn't be wasting their time.
Helps you pick up chicks too!
Cheers,
Pete
Z Web World
Mobile Dj, Web Design,Photography, Bullshit Artist!
"I don't want a pickle,
I just wanna ride my motorsickle."
Arlo Guthrie 1968<i></i>
Here's my two cents worth.
The reason you turn the bars right to go left and left to go right is due to the gyroscopic effect of the front wheel. When you try to change the plane in which a gyroscope (your rotating front wheel) is turning, the effect of any control input is felt by the gyro 90 degrees after the control input.
By turning the handlebars to the left for instance, causes you to turn the forks to the left. Imagine those forks rotating 90 degrees in the direction of rotation of the front wheel. (If you put your hand up in front of you, and pretend it's your forks you'll see what mean) You will notice that the imaginary rotatation of the forks now has them cantered to the right. Any thing attached to the gyroscope will then canter or lean to the right. The opposite thing happens when you trn the bars to the right.
Any questions. If you are still confused, I suggest studying "Rotary Wing Theory of Flight" (Helicopters).
Next weeks lesson will be on how hanging off lowers your centre of gravity and the effect this has on the "thrust vectors" and hence your rate of turn or turn radius. <i></i>
You can ride fast, like REV, without hanging off by simply taking the weight on your footpegs and using them as a counterbalance.
IE. If you want to go right, you place your weight on the left peg and the right bar and visa versa for turning left.
This method of riding fast is good when you wear your Draggin Jeans because if you slide around on them you get gravel rash on your bum from the kevlar.
Hanging off is much easier in leathers....
(Some say hanging out in leathers is cool too)
Rgds BUSGO
"TAKE MY ADVICE"
I'm not using it anyway!<i>Edited by: BUSGO at: 29/12/06 11:05
</i>
I'll add my two bob's worth.
The reason you "turn right" initially before the bike turns left is that you have to introduce some instability to start a turn. When the bike is stable, ie in a straight line or even at a constant speed around a constant radius turn, the bike is in a stable condition, ie the centre of gravity is directly above the wheels (going straight) or the combination of centripetal force and weight is acting directly down through the tyres while cornering. You can actually turn a bike without any force on the handle bars, we've all done it riding push bikes with no hands. You actually lean slightly into the corner. The weight shifts over slightly and now the bike will fall over. It will continue to fall over as long as the weight is outside the contact patch, but if we correct the weight angle, the bike steadies at the new angle of lean and turn. By pushing the handle bars the opposite way for a more rapid entry, all that happens is the front tyre moves out to the right, ie the weight is now acting just to the left side of the contact point, the bike will then turn to the left to re-establish stability by generating some centripetal force. Ie you turn a corner.
The rate of turn is dictated by lots of things, the fork angles, the wheel gyroscopics, the crank gyroscopics, the mass of the bike, length of the wheelbase etc etc. There's no easy fix, except, lighter wheels, lighter crank, shorter wheelbase, steeper steering etc. The best way to check what effect steering angles have is ride a normal road bike, then jump on a velodrome track bike. The track bike has a steeper angle and turns on a sixpence, watch some track racing and see how fast they change direction.
OK, over to someone to shoot holes in it all! <i></i>
I too suffer from the kevlar in the draggin jeans.I now where bike pants style undies and thin shorts under the jeans to stop the irritation.It feels like prickly pear under your thighs and almost made me throw them out because of it. <i></i>
Quote:If you want to go right, you place your weight on the left peg and the right bar and visa versa for turning left.
Busgo.... shouldn't you be loading up the left foot peg for a left turn and right peg for a right ? When I shift my weight on the pegs I'm usually doing it on the same side as I'm turning. Maybe I've been doing it wrong. I'll test it later today when I head out for a run.
As to the hanging off debate.... its comforting to know there are technical reasons why it works.... I just do it because I enjoy it. I do it less now that I've got the Tobin because with a lower centre of gravity I don't feel the need as often. Good topic - thanks spaman. The older I get, the better I was. Regards.... Rob<i></i>
Interesting point about the tobin astro.I had a spare seat without the foam for future testing lying around so i fitted it and went for a ride.The bike steers better with the foamless seat.Like the vfr it feels like i can lean the rear tyre better from the seat(with weight transfer) rather than just steer the front.it definately turns better at low speed street intersections.Whether thats because theres more weight on the seat and less on the pegs or less weight on the bars,i don,t know yet.I get the impression the busa is way nose heavy and would probably low speed turn better 2 up.for my 2 girls i have a tandem long pram.When only the eldest (heaviest) is in the front and the youngest(lightest) is in the back it is quite hard to steer.When the order is reversed it is far easier to steer even though the total weight is the same.Putting lighter exhausts and subframes,swingarms on etc is great but it is pulling alot of the weight off the back of the bike,worsening (I believe )its front to rear weight bias.Perhaps i should lower the rear and see how it feels?or titanium engine bolt kit and kevlar tank thats about 7kg off the front i,m hoping. <i></i>
Weighting the pegs and bars up is a balancing act.
I think you will find that when you have your weight on the pegs you load up each knee to retain your line and you subconsiously either lean from side to side or press forward on the bars on the side you are turning in to.
I think you will notice that if you use the "hanging off" method, that you have little pressure on the inside foot which allows you to lift it if necessary.
Like ROSSI does when he goes in too hot.
Rgds BUSGO
"TAKE MY ADVICE"
I'm not using it anyway!<i></i>
Busgo... I think you're right. Loading up the pegs seems to be a progressive shift from one side to the other and the initial part as a much a matter of securing my perch on the seat and bringing my head, upper body, knees and feet into position as it is to transfer weight. (Mind you... the one causes the other, so which is happening in what order and for what reason isn't really worth debating).
I'm actually holding the load on the inside peg (ie : left for left corner) longer than I thought - because at about the point where I'm powering out of the apex it helps to keep the bike keeled over and stops it standing up too quickly under the acceleration. Then, the weight bleeds across to the outside peg when I actually do want her to stand up.
The intriguing part is that I'm only fluid with the whole process if I ride "by the seat of my pants" so to speak. If I try to consciously record, analyse and control all of these things, it all goes haywire.
I had a play with this on the 80k/ph section of the old pacific hwy yesterday and noticed pretty quickly that there are a bloody lot of intuitive actions going on. All I really noticed was that if I was mentally trying to inventory and analyse each of them - all I really ended up with was messy cornering. Trying to judge the effects of different inputs... plus toss in a slight variation to see if it created a different feel and result compared to the previous corner took a lot of conscious background processing and it messed up my timing.
The older I get, the better I was. Regards.... Rob<i></i>
I agree Astro, the more you try to think about it the less effective it is for me too.
Pre corner preparation is better than mid corner assessments.
I think you will find that most of the faster riders actually stand the bike up as early as possible so that they can get on the gas quicker and with less chance of a highside.
Rgds BUSGO
"TAKE MY ADVICE"
I'm not using it anyway!<i></i>
I am glad to read this
reason is this:
Ever since I low sided the busa - gaining confidence again in cornering took a while - I read lots up on it as well as I had never crashed in a corner before & haven't since either. But given a high percentage of crashes are in corners for bikes - I decided to practice with it.
First thing I tried was either sitting up close to the tank - or pushing my arse as far back as I could.
Well sitting up close made me feel top heavy & felt like there was more pressure on the front tyre & hence my entry speed to corners suxed!!
Slid my arse back & of course the weight evened out & solved part of my cornering problems.
Next was the hang off....
If anyone on the ride on saturday down here noticed - I hang off the bus heaps!!!
While practicing the hang off - how to use weight on my pegs while doing it as well - I found good markers to know if I am hanging off enough - in short - if the outside knee is touching the outside elbow on the tank - I am happy I also happen to feel really comfy doing this as well. (Also while doing this a mate who has been riding for 10 years road & racing dirt all his life - was on a cbr250 & he creams nearly all big bikes in the corners due to the lighter weight & experience - so chasing him through the likes of reefton & black spur plus practicing all of that above got my corning up to scratch ;) )
Now before doing all of this - like I said I read up heaps - & read something pretty much to the same affect of the first post
So if your having cornering issues - give some of that a try & get ya arse off the damn seat!!! (Feels wicked too when you nail it earlier out of corners as well!!) "Busa riders always count in three's.... 100, 200, 300"
<i></i>
I do it the Busgo way, I think. I'm more upright and the bike does all the leaning, and the faster I go the more I lean opposite to the way the bike is going, counter steering and putting all the weight on the opposing peg.
You can go bloody quick like this and it feels more stable for the less skilled rider, but after a certain speed hanging off is the only way to do it. Unfortunately, I don't go fast enough to practice this technique anymore, (within my skill level) and I still haven't made it to the track yet.
Some of you guys are saying the same thing...but with different words...if you know what I mean. <i></i>
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