noob rider weight transfer

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noob rider weight transfer

Postby lotii10396 » Tue Oct 01, 2013 12:54 pm

Hiya all, on w/end went for my first ride in 30 years on my *new* 1991 A8 - awesome. Was following experienced riders so this helped enormously - HIGHLY RECOMMEND FOR NOVICE RIDERS LIKE ME!

After an hour or so I was confident enough to try a few cornering adjustments and are pretty comfortable with lean angles and throttle as key parts of good cornering technique. However one of the things I noticed was that by moving my body position I can move weight from the front to the back or vice versa. I played around a bit with this during cornering (usually pre & post apex) but to me it made little or no difference - obviously not pushing very hard. My limited understanding is that during cornering there is a tyre load shift from front (understeer) to back (oversteer) and this would also be affected by uphill/downhill corners and throttle/braking application. Normally you want a loaded tyre for grip but I'm used to cars where cornering loads transfer to the outside tyres, so I'm confused as to how this theory applies to a cornering bike. More weight equates to more vertical load (+grip) but also translates to more sideways load during cornering........

Body weight naturally transfers to rear during corner exit (throttle), so perhaps am I thinking too much about this and should just keep a natural "neutral" position?

This tyre load question also applies to upgrades I have read about the GPz - especially a 17" rear rim & therefore bigger & grippier tyre. Does more rear grip mean more "push" therefore more understeer, and does this affect the designed grip balance of the bike? Or is more tyre grip better under all circumstances?
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Re: noob rider weight transfer

Postby tim » Tue Oct 01, 2013 6:52 pm

Gday and welcome.

I haven't got much time so I'll just get the ball rolling.

Some basics to get right in your head and in practice.

Acceleration (faster or slower) of a bike tries to stand bike up through gyroscopic effect of rotating mass of wheels. The more acceleration, the more force.

The further you get off the bike, the less your lean angle, the more grip.

Get off the bike an amount appropriate for where and how you are riding. One butt cheek back and off the seat is generally plenty for the road even at good pace.

Slowing down in initial stage of corner, weight transfers to front tyre, more grip is used for slowing, less grip available for cornering, going into a corner the front will wash out if over burdened through rough use of brakes, too much angle, road traction changing etc.

"Maintenance throttle" in a corner can balance traction load between front and rear.

Getting on the gas exiting shifts weight distribution to rear tyre which is good because larger contact area, but has it's own issues to deal with. The rougher your throttle application, too early or hard on throttle, too much lean angle etc increases chance of sliding rear. Chopping the throttle if near the limits of traction will transfer force away from the rear tyre to the front and slide the rear.

Until you're right at the limit YOUR position on the bike is more important with regard to how comfortable you are on the bike cornering at the speed you are, how hard it makes you hold the bars and therefore stop the front tyre from reacting correctly as it needs to to changing conditions........

Not everything, but it's a start :kuda:
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Re: noob rider weight transfer

Postby MAXUMIS » Tue Oct 01, 2013 7:37 pm

tim wrote:Gday and welcome.

I haven't got much time so I'll just get the ball rolling.

Some basics to get right in your head and in practice.

Acceleration (faster or slower) of a bike tries to stand bike up through gyroscopic effect of rotating mass of wheels. The more acceleration, the more force.

The further you get off the bike, the less your lean angle, the more grip.

Get off the bike an amount appropriate for where and how you are riding. One butt cheek back and off the seat is generally plenty for the road even at good pace.

Slowing down in initial stage of corner, weight transfers to front tyre, more grip is used for slowing, less grip available for cornering, going into a corner the front will wash out if over burdened through rough use of brakes, too much angle, road traction changing etc.

"Maintenance throttle" in a corner can balance traction load between front and rear.

Getting on the gas exiting shifts weight distribution to rear tyre which is good because larger contact area, but has it's own issues to deal with. The rougher your throttle application, too early or hard on throttle, too much lean angle etc increases chance of sliding rear. Chopping the throttle if near the limits of traction will transfer force away from the rear tyre to the front and slide the rear.

Until you're right at the limit YOUR position on the bike is more important with regard to how comfortable you are on the bike cornering at the speed you are, how hard it makes you hold the bars and therefore stop the front tyre from reacting correctly as it needs to to changing conditions........

Not everything, but it's a start :kuda:

that is a perfect answer !! the only thing I can add is spinning mass , wheels do some but the main prob is the crank/other high spinning parts with a bigger style of motor, so in saying that you may have to hang off the bike more ..?
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Re: noob rider weight transfer

Postby mark1 » Wed Oct 02, 2013 10:11 am

I recommend training the earlier the better otherwise you end up unlearning all your bad habits before picking up the good habits.Not sure what is available in SA try
http://www.stayupright.com.au/
http://toprider.com.au/
http://hart.honda.com.au/
8)
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Re: noob rider weight transfer

Postby lotii10396 » Wed Oct 02, 2013 12:31 pm

Thanks Maximus,

at at the speeds I ride having the most comfortable, stable position as a priority makes perfect sense. Just because I can move around doesn't mean I should: staying still takes a variable out of the equation and lets me concentrate on refining other techniques. I also now understand why advanced riders do move around, it transfers rider mass to a lower centre of gravity (+ possibly a lesser cornering radii) = less lean = maximum speed for the available grip, but honestly I hope to *never* be riding at the point where this is necessary. I hadn't even thought about the gyroscopic effect - but now that you have mentioned it it's obvious. My driving/riding priority is always been about ensuring I have LESS than the optimum entry speed, experience tells me that braking or steering corrections to make a corner apex unsettles car balance (and generally asks more of tyres) so there's no reason bikes should be any different. Unless I'm on a racetrack I prefer smooth over frantic....

And Mark1 - yep, I do want to attend a training course. None of those you listed were in SA but I have just been speaking with http://www.radskills.com.au - they offer a "one-on-one" road-riding & cornering course (including bike set-up) which sounded like my cup of tea. Anyone have any experience with these guys?
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Re: noob rider weight transfer

Postby tim » Wed Oct 02, 2013 1:42 pm

Yeah, thanks Maximus :D
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Re: noob rider weight transfer

Postby Smitty » Wed Oct 02, 2013 7:42 pm

.. in all this, don't forget countersteering
and also that the bike (generally) has more grip than you will ever use
so lean..lean it further is also something you need to take into account
(when thinking about Tim's original list of points)
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Re: noob rider weight transfer

Postby MAXUMIS » Wed Oct 02, 2013 9:11 pm

thanks Tim for your info ! I just had my two cents as well ? but as Smitty said that's pretty much near all I do in track conditions / whack on the handle bars to get my ole girl to go through the tighter "styles" of corners ! Im far from the best but it works for My style of riding . :)
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Re: noob rider weight transfer

Postby Nelso » Wed Oct 02, 2013 10:15 pm

tim wrote:Acceleration (faster or slower) of a bike tries to stand bike up through gyroscopic effect of rotating mass of wheels. The more acceleration, the more force.


Sorry Tim, but accelerating doesn't stand the bike up. You pulling or pushing on the bars when the bike accelerates is what stands the bike back up. All the gyroscopic effect of the engine and wheels does, is make the bike harder to change direction; therefore, the more rotating mass, the harder to get the bike to tip into corners and the harder it is to stand it back up again. By accelerating through a constant arc, the increased centrifugal force might help to stand the bike back up, but it's the rider's input that has the greatest effect and has nothing to do with any gyroscopic force.
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Re: noob rider weight transfer

Postby tim » Wed Oct 02, 2013 10:43 pm

Cool thanks Nelso :)

Why does the bike stand up when you slow down by applying the brakes when leant over?
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Re: noob rider weight transfer

Postby Nelso » Wed Oct 02, 2013 11:19 pm

lotii10396 wrote:Hiya all, on w/end went for my first ride in 30 years on my *new* 1991 A8 - awesome. Was following experienced riders so this helped enormously - HIGHLY RECOMMEND FOR NOVICE RIDERS LIKE ME!

After an hour or so I was confident enough to try a few cornering adjustments and are pretty comfortable with lean angles and throttle as key parts of good cornering technique. However one of the things I noticed was that by moving my body position I can move weight from the front to the back or vice versa. I played around a bit with this during cornering (usually pre & post apex) but to me it made little or no difference - obviously not pushing very hard. My limited understanding is that during cornering there is a tyre load shift from front (understeer) to back (oversteer) and this would also be affected by uphill/downhill corners and throttle/braking application. Normally you want a loaded tyre for grip but I'm used to cars where cornering loads transfer to the outside tyres, so I'm confused as to how this theory applies to a cornering bike. More weight equates to more vertical load (+grip) but also translates to more sideways load during cornering........

Body weight naturally transfers to rear during corner exit (throttle), so perhaps am I thinking too much about this and should just keep a natural "neutral" position?

This tyre load question also applies to upgrades I have read about the GPz - especially a 17" rear rim & therefore bigger & grippier tyre. Does more rear grip mean more "push" therefore more understeer, and does this affect the designed grip balance of the bike? Or is more tyre grip better under all circumstances?


The thing you have to remember is that the rider's input has a far greater effect on the handling of a bike compared to any other vehicle. The position you put your body in will effect your centre of mass, which will effect the centre of mass of the moving vehicle (combined rider and bike), which has a profound effect on the way it handles. More often than not, the rider's movements have a negative effect on the handling of the bike.

When starting out, it's best to keep your body in one position and learn to coordinate the controls of the bike. When you have that under control, you start to move your upper body around to manipulate your COG and you start to get a feel for what it does to the handling of the bike. Once you have a good feel for the bike and are running out of tyre, you can learn to 'hang off' the bike. Unfortunately, most people skip straight to this step and don't learn it properly as they just start hanging their arse off, which messes up their body position.

Moving around on the bike incorrectly will unsettle it and there's more to it than most people realise, so it's best to leave that skill until later in your development. The same can be said for trail braking, which when done right greatly improves the way a bike tips into a corner, but can be disastrous teaching it to a beginner.

Here's some basic fundamentals to start with:

Counter steering tips the bike into corners and stands it back up again. It is your input on the handlebars that have the greatest effect on the direction the bike goes. Once the bike tips in, the less input by your hands the better the bike will handle through the corner. More people lose the front end by leaning on the bars mid corner than any other way.

Accelerating through a corner settles the bike. It has more to do with the antisquat properties of the swingarm geometry and the weight transfer it generates, but getting on the gas settles the suspension of a motorbike and helps it track around the corner better! If you don't accelerate, it will understeer out of the corner; but, If you accelerate too aggressively and spin the rear, it will oversteer. If the geometry is set up right on the bike, it shouldn't understeer coming out of a corner if you are accelerating.

The greater the lean angle the less grip, so adjust your throttle and brake application accordingly. This is an obvious one and it's straight physics. The lower you lean the bike, the more horizontal and less vertical force are applied to the tyre's contact patch, which reduces friction. This means you can brake and accelerate harder when more upright and must brake and accelerate less when leaned over.

When learning: slow and wide in, smooth and tight out. Start your corner on the outside of the corner at a comfortable pace (which means do your braking early so there's no chance of overcooking the corner) and accelerate smoothly through the corner aiming to finish on the inside of your lane.

Where you look, you will go. Always look through the corner to where you want to be. Target fixation is a very dangerous thing which catches all new riders out at some time or another. When things go wrong and your survival reactions start to take over, remember to look through the corner.

Relax your body. Tension is the enemy! The tighter your grip or the stiffer your body, the more input you put into the bike which will unsettle it.

Be smooth on the controls. The throttle, brakes and clutch are not on/off switches for a reason. It's even more important to be smooth on a bike than in a car for obvious reasons.

The best advice is to get as much rider training as possible. It would be worth travelling to Philip Island to do the California Superbike School to learn the fundamentals of cornering as well as doing as many practical road craft courses like the Stay Upright course as they all offer something different and you will always learn something knew. One thing to keep in mind is that every dollar you spend on rider training will stay with you forever, where as any money spent on bikes to make them go better gets passed on when you sell it; and everyone knows that a good rider will be better on a shit bike than a shit rider on a good bike any day of the week.

Hope that helps.
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Re: noob rider weight transfer

Postby Nelso » Wed Oct 02, 2013 11:21 pm

tim wrote:Cool thanks Nelso :)

Why does the bike stand up when you slow down by applying the brakes when leant over?


Momentum?

Edit: It's the front brake that usually stands riders up and not the rear (as the rear brake is often used to pull them in tighter) and you can can keep tracking around the corner when you apply the front brake without it standing up (I've done it plenty of times myself), so I think it's more the rider's momentum and the input that it has on the bars more than the bike itself.
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Re: noob rider weight transfer

Postby tim » Thu Oct 03, 2013 1:43 pm

Yup makes sense :)
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Re: noob rider weight transfer

Postby lotii10396 » Tue Oct 08, 2013 11:20 am

Thanks to everyone - it's been very informative and helpful. I've done a fair bit of time on the track in cars and understand the basics of settled suspension & mass during cornering. In a mid-engined sports cars it is not recommended to get off the throttle mid-corner, and never, ever emergency brake - but honestly that depends on the car....another story! My original question came up because I noticed that during "real-world" cornering (ie dips, inclines, etc.) there are small mass transfers to the front to rear tyres (and vice versa) that are not created by braking or throttle & on a bike you have the physical option to move your weight forward or back to either counter or exaggerate. In particular as mass comes off the front wheel I figured less mass = less grip, which got me wondering whether to move my weight forward.

I've been doing plenty of "training" rides (60-80km/h zones through the Adelaide Hills) and staying nice and still on the bike and trusting the mechanical tyre grip is definitely the way to go for me. I also agree with a relaxed upper body, though I do find gripping the tank with the legs helps keeps me more stable during cornering. The GPz seems a very sorted bike, to me it is both stable & nimble (which are obviously opposites) a nice balance of the handling vs stability challenge that exists with any vehicle design. Once I am a much better rider I would be curious to ride a modern pure super sports bike - obviously back in 1984 the GPz was the premium "sports" bike but is now considered a "sports-tourer" so obviously there's been some big advances in bike design over the last 30 years or so. And whilst that sounds logical, the pure handling and road behaviour of supercars from that era (like the Lotus) aren't that far behind a modern supercar - they are dated by advances in materials and the rest of the package (tyres, brakes, gearboxes, engines, electronics, etc.).

One point I noted from the posts was that using the rear brake during cornering tightens the line. The scenario I'm visualising is a big sweeper with a tightening radius, so mid-corner I either have to slow the bike down (brake) or tip it over more. As mentioned I'm kinda dialled in to not use brakes during cornering, so is using the rear brake (and front brake) a genuine riding technique or more an option when you haven't quite got it right?
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Re: noob rider weight transfer

Postby Nelso » Tue Oct 08, 2013 3:05 pm

lotii10396 wrote:One point I noted from the posts was that using the rear brake during cornering tightens the line. The scenario I'm visualising is a big sweeper with a tightening radius, so mid-corner I either have to slow the bike down (brake) or tip it over more. As mentioned I'm kinda dialled in to not use brakes during cornering, so is using the rear brake (and front brake) a genuine riding technique or more an option when you haven't quite got it right?


There are three options on a bike to pull in tighter. Slow down, tip the bike over more, or lower the Centre of Gravity.

To slow down mid corner, most use the rear brake to pull them in tighter because it doesn't unsettle the bike as much and you can keep the weight off the bars and let the front end do its thing. To you use your front brake mid corner takes finesse; it can be done, but it's an advanced skill. It's best to stay off the brakes once you apply the throttle, but not all corners and situations allow that.

To pull in tighter you can also counter steer more to tip you over further (just be careful not to keep leaning on the handlebar as you might wash the front end out and lowside), but you can also use a "Hook Turn", which is lowering and moving your mass inside the bike. By changing the position of the centre of combined mass of the bike and rider you can turn a tighter arc with the same lean angle and speed, hence why you see MotoGP riders hanging right off the bike. The biggest difference to cars is the ability to manipulate your body to change the centre of gravity of the vehicle, so you can use this to pull you in tighter mid corner, or stand the bike up more to increase the size of the contact patch of the rear tyre as you drive out of a corner. You don't have to have your arse hanging off the seat to do it either. ;)
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