Yamaha NIKEN Three Wheel Leaning "Sport Bike" ... Cool or Conflagration?

[Arizona Wayne]

You need to ride a MP3 to understand how it's suspension works, Dusty. 

[Huzo]

Randy , do just a bit of reading , that's all I can say . Start with Kevin Cameron . What you are describing is stability , not traction , two different concepts . The laws of physics are the laws of physics are the laws of physics .

 Dusty

[Huzo]

You need to ride a MP3 to understand how it's suspension works, Dusty. 

!!!

[oldbike54]

You need to ride a MP3 to understand how it's suspension works, Dusty. 

 I have ridden one Randy , they are pretty cool . That doesn't change the laws of physics as they apply to traction .

 Something I am curious about , with two front tires , there must be some weight transfer to the outside tire during cornering , right ? Or are the forces involved in the way a leaning vehicle corners canceling the weight transfer . Prescott , Huzo , Kirby ? One of you engineers/physicists help me out here .

 Dusty

[Huzo]

To be honest Dusty, I'm not a Physicist, but I did engineering at Uni and have a working knowledge as do you.
Having said that.
Yes the leaning of the vehicle will place the C of M toward the inner tyre which reduces the tendency to "flip", but the total mass hasn't changed so the resistance to centripetal force is unchanged.
(Notice I didn't use the term "centrifugal", it's actually an incorrect term and it's one "c" word a true Physicist won't use).
I feel a thread coming on, now back to the Dusty,  Arizona Wayne bout.
I was enjoying that. 

[oldbike54]

To be honest Dusty, I'm not a Physicist, but I did engineering at Uni and have a working knowledge as do you.
Having said that.
Yes the leaning of the vehicle will place the C of M toward the inner tyre which reduces the tendency to "flip", but the total mass hasn't changed so the resistance to centripetal force is unchanged.
(Notice I didn't use the term "centrifugal", it's actually an incorrect term and it's one "c" word a true Physicist won't use).
I feel a thread coming on, now back to the Dusty,  Arizona Wayne bout.
I was enjoying that. 

 Yeah , I understand about centripetal (or fake) force , it is the string that pulls a bike towards the center of an arc , and how CoG or mass plays its role in cornering . What I am curious about is how the vectoring forces (I may not be saying this right) , or the rotation of mass around the steering center of a vehicle with two front tires affects load on the outside tire . Maybe Huzo explained it , gotta reread his post .

 Dusty

[Arizona Wayne]

I have ridden one Randy , they are pretty cool . That doesn't change the laws of physics as they apply to traction .

 Something I am curious about , with two front tires , there must be some weight transfer to the outside tire during cornering , right ? Or are the forces involved in the way a leaning vehicle corners canceling the weight transfer . Prescott , Huzo , Kirby ? One of you engineers/physicists help me out here .

 Dusty

If there is on a MP3 I can't feel it.  I have never taken any physics and my knowledge is by seat of my pants experience riding MP3s, road racing MCs in my past.  I can't explain how things I feel/experience are happening, just what I can do as a rider with what's happening.  All I know is the front end on a MP3 is far more solid  on paved road whether dry or wet than on any MC I have ever ridden.   Going thru a curve on a MP3 at a good clip is simpler to deal with than on a mc   It's a no brainer.  You don't even have to think about it.  You just do it.     On a loose surface the opposite is true compared to doing it on a MC w/dirt tires.   

In reality when turning left in a corner I guess some weight is shifting to the right but you hardly feel it happening  due to 2 separate front wheels sharing that weight and the left lean of your scooter body w/you on it.

[Huzo]

If there is on a MP3 I can't feel it.  I have never taken any physics and my knowledge is by seat of my pants experience riding MP3s, road racing MCs in my past.  I can't explain how things I feel/experience are happening, just what I can do as a rider with what's happening.  All I know is the front end on a MP3 is far more solid  on paved road whether dry or wet than on any MC I have ever ridden.   Going thru a curve on a MP3 at a good clip is simpler to deal with than on a mc   It's a no brainer.  You don't even have to think about it.  You just do it.     On a loose surface the opposite is true compared to doing it on a MC w/dirt tires.   

In reality when turning left in a corner I guess some weight is shifting to the right but you hardly feel it happening  due to 2 separate front wheels sharing that weight and the left lean of your scooter body w/you on it.

You got it !
On a trike you are sitting (fundamentally) upright in a turn and the rig is being accelerated toward the turn centre, your body wants to continue straight on (Newton), and you'll feel it as a tendency to be, well ummm "tossed off" so to speak.
Now in the case of the other thing...
Although the rig is being accelerated towards the centre as before, the mass is leaning and the summation of gravity (acting vertically) and centripetal force ( acting horizontally inward) combine on your body to give a resultant vector directly from the centre of your butt, up through your spine and out through the centre of your cranium ! It's akin to the theory of why you don't feel any sideways forces in a correctly balanced turn in an aircraft, ( or a glider if you gave enough "class" to fly one) 
As a subtext though, I'm a bit dubious about having massive braking advantage/bias on the front with the centre of mass behind and the (theoretical) tendency to swap ends under hard braking.
Reminiscent of ground looping tail wheel aircraft, Pawnees and Piper Cubs et al...
But anyway, they seem to work ok..Never been on one, never will.

[oldbike54]

 Randy , that weight shifting thing is what I am trying to work out , but it seems Huzo explained that there is no weight transfer .

 So , exploring this just a bit farther , here is what I think you are experiencing with the MP3 VS a single track vehicle , and how this isn't traction but stability .

 First , we will delve into the traction thing , which is nothing more than friction . Place one hand on a table W/O any pressure applied , now slide it across the table , it won't take much force . Now, push down on the hand and slide it across the table , notice it takes more force to make the hand slide . That is traction being increased by loading . Or do the same experiment with a board tied to a rope . Doesn't matter whether it is placed on its narrow or wide side , it requires the same amount of force to move . Still just traction .

 Now , about the increased stability provided by the two front tires . Try standing on one leg , you wobble back and forth , now place both feet on the ground , you become more stable , correct . Pretty sure that this is what you are experiencing , stability , because once again , traction is not related to contact patch . 

 Dusty

[Darren Williams]

One of the things I enjoy about riding two wheelers is tilting the horizon (leaning). If this technology keeps improving, I could see it extending my riding years. This is exciting to me.

The physics of what is happening up front on one wheel verses two when the vehicle leans over moving the CG and resultant forces is pretty cool to contemplate.  I would think as the bike leans over the inner tire will see an increase in load, unlike a car that doesn't lean much where the centripetal force loads up the outer tire. Seems like the suspension springs might accentuate the forces. Science is cool. 

[Huzo]

Probably suggesting Dusty that centre of mass although slightly displaced "inward" gives less tendency to flip.
It's the balancing of the vectors of gravity (vertical) and centripetal (horizontal) on the acceleration sensors in your ears (vestibular canals) that stop you sensing sideways accelerations and that keep the forces straight through your body from your ass to your head and that is the resultant force we experience for 99% of our time in earth.
All very familiar and reassuring. If you hang a pendulum on your fairing screen it'll point straight down at you petrol cap, now I haven't done it, but I'll bet my flat tappets that in a turn on your motorbicycle, that pendulum will always point to the gas cap no matter how far you lean,
Unless you crash 
Same principle.

[Huzo]

One of the things I enjoy about riding two wheelers is tilting the horizon (leaning). If this technology keeps improving, I could see it extending my riding years. This is exciting to me.

The physics of what is happening up front on one wheel verses two when the vehicle leans over moving the CG and resultant forces is pretty cool to contemplate.  I would think as the bike leans over the inner tire will see an increase in load, unlike a car that doesn't lean much where the centripetal force loads up the outer tire. Seems like the suspension springs might accentuate the forces. Science is cool. 

In one respect the inside tyre will be loaded up Darren, but remember that the C of M is above the point of support and there is still a tendency for the whole shooting match to go arse up if you go excessively fast, by loading the outside tyre (like a car), but I don't have an empirical idea of the transverse load bias in a turn.
The load on the outside tyre must be increasing as a function of turning forces though, because every man and his dog knows that if you keep going faster and faster it will eventually flip toward the outside.
Ouch !!!

[Darren Williams]

It seems logical that the vertical and horizontal forces would be equalizing based on lean angle that lowers and moves the CG inward , until you run out of lean angle.  So that would then lead me to think the balance point of the two forces to be in the middle of the two front wheels giving no advantage to either.

[rodekyll]

so if all the yada-yada says the force is on the inside wheel, why do circle track cars have the outside front wheel reinforced?  Why does a hack want to lift the car when it's turning into it?  Why does my trike squat the outside wheel?  Newton?  Bueller?   

[oldbike54]

so if all the yada-yada says the force is on the inside wheel, why do circle track cars have the outside front wheel reinforced?  Why does a hack want to lift the car when it's turning into it?  Why does my trike squat the outside wheel?  Newton?  Bueller?   

 Those vehicles don't lean towards the inside of the arc .

 Dusty

[bad Chad]

I'm not sure this is completely relevant, but every comparison of a F1 car vs Moto go bike or similar on the same track and conditions, the car spanks the bike, only because the car is able to corner much faster than a bike.

[oldbike54]

I'm not sure this is completely relevant, but every comparison of a F1 car vs Moto go bike or similar on the same track and conditions, the car spanks the bike, only because the car is able to corner much faster than a bike.

 Cornering speed is higher , but above 120 MPH a modern f1 car accelerates much faster than a motogp bike . Aero plays a role in both acceleration and cornering speeds .

 Dusty

[Arizona Wayne]

, I'm a bit dubious about having massive braking advantage/bias on the front with the centre of mass behind and the (theoretical) tendency to swap ends under hard braking.
.
[/quote]


My maxi-scooters have linked braking just like most Tonti Guzzis by the 2 front handlebar levers.   1 lever pulls 1 front brake & the rear brake.  The other lever pulls the other front brake.  So all your brake control is in your hands and it's easy to control the braking this way.   Also you have 3 tires/brakes instead of just 2 like on a 2 wheeler and very little front nose dive like on a MC when you grab a handfull at once.  Your braking is much more evenly distributed like on a car.    Your throttle is twist & go with a centrifugal clutch to belt drive.  No gear changing, which takes a little getting used to.

In 9 years of riding my MP3s I have never had an issue of the rear end ever wanting to come around on me when stopping.  It always stops straight and true.    Maybe the fact the motor/rear drive is all 1 unit helps.   Some maxi scooters are more set up like MCs in design, but not the Italian 1s.

[twowheeladdict]

Randy , do just a bit of reading , that's all I can say . Start with Kevin Cameron . What you are describing is stability , not traction , two different concepts . The laws of physics are the laws of physics are the laws of physics .

 Dusty

Dusty, you are missing the point.  What you are stating is theoretical and applies to a consistent surface.  A little debris, or slick in the road and you are going down.  But with two tires up front, one tire can go through the debris and lose traction, but the other tire that isn't in the debris retains traction and takes you through the curve.

[oldbike54]

Dusty, you are missing the point.  What you are stating is theoretical and applies to a consistent surface.  A little debris, or slick in the road and you are going down.  But with two tires up front, one tire can go through the debris and lose traction, but the other tire that isn't in the debris retains traction and takes you through the curve.

 I stated that in a different post . My original clarification to Huzo's post was simply in reference to the fallacy that traction is dependent on the size of a contact patch .

 Dusty

[Trevor G]

I saw this first in a magazine test and later confirmed it on my own MP3 400

At speed, in my case 70mph when pushing it hard through a corner, the front tyres have a somewhat unnerving characteristic of "walking" across the road. Describing it would suggest that one tyre slips a little, then the other grips, because the net result is that the front end develops a slight "wagging" or wig=wag motion.

I found that disconcerting, because it drifted towards the outside of the corner at the same time, but only when pushing it hard at high speed (which is the way I ride).

[Huzo]

so if all the yada-yada says the force is on the inside wheel, why do circle track cars have the outside front wheel reinforced?  Why does a hack want to lift the car when it's turning into it?  Why does my trike squat the outside wheel?  Newton?  Bueller?   

Dunno 'bout the others, but I didn't want to suggest that the weight is on the inside wheel.
Indeed, if you look at the contraption from the front, and imagine a point where each (front) wheel touches the ground and another point on the C of M, which will be somewhere near the centre of your guts all things considered, you will see a triangle (3 points), but not an equilateral one. There will be one of the non horizontal,  (can't say vertical) lines a bit longer than the other.
As the things enters a turn, the C of M tries to tip the triangle over, subsequently weighting the OUTSIDE wheel (point) more heavily as a function of the mass and rate of turn.
However...
The RIDER won't feel a sideways acceleration though,  due to the aforementioned resultant vector straight through the vertical centreline of your body.
Honestly.

[Huzo]

I'm not sure this is completely relevant, but every comparison of a F1 car vs Moto go bike or similar on the same track and conditions, the car spanks the bike, only because the car is able to corner much faster than a bike.

The car can slide without the whole lot becoming negatively stable, unlike a bike.
Positive stability is when a system will revert to it's original state when not actioned upon by an external force.
Neutral stability is when it will not depart further nor return to original state when external force removed, (car)
Negatively stable is when, once the system is disturbed by external force, the departure into oblivion will be accelerated and not return to original state. (Bike)
Also I'd suggest that the car has more mass.

[wheaties]

The NIKEN just looks too arachnid for me.

I had the same thought.  Something like this perhaps?

[Arizona Wayne]

I saw this first in a magazine test and later confirmed it on my own MP3 400

At speed, in my case 70mph when pushing it hard through a corner, the front tyres have a somewhat unnerving characteristic of "walking" across the road. Describing it would suggest that one tyre slips a little, then the other grips, because the net result is that the front end develops a slight "wagging" or wig=wag motion.

I found that disconcerting, because it drifted towards the outside of the corner at the same time, but only when pushing it hard at high speed (which is the way I ride).

Sounds to me like you ride your MP3 too fast for it's capabilities some times, unless you don't mind how it reacts.