Any idea why?

**beyond** · 31st August 2006, 08:47

Just a thought (second time this year).

I've noticed this for some time and it's even apparent on photos taken from the side of the road. One of my riding buddies mentioned it the other day as well and he rides a GSXR1000 and was following me for a bit.

When cornering, my GSX1400 does not seem to have the same lean angle as a full on sportsbike, for the same corner, at the same speed. This of course is good for me as it means the hard bits don't touch down so early. BUT, why does a sportsbike have to lean more than mine to get around a corner at the same speed?

Is this a wheel base/physics thing? Weight? Seems a bit strange but it is apparent.

Any ideas from the weight versus mass versus wheelbase, cornering phyics specialists out there??

**dnos** · 31st August 2006, 08:53

i wont say im an expert, any physics knowledge i did have is pretty much forgotten since high school.
But i think weight would have a lot to do with it. and perhaps the centre of gravity being higher or lower?
Would be interested to hear this from the experts meself

**98tls** · 31st August 2006, 08:55

seems strange eh....maybe its tyre profile....i have tried both 180 and 190 rear tyres and there is a difference on turn in....just guessing really...will be interested in others theories.

**Devil** · 31st August 2006, 09:34

Originally Posted by dnos

But i think weight would have a lot to do with it. and perhaps the centre of gravity being higher or lower?

This is the reason.
For the extreme example, follow a cruiser. Really low weight and they hardly lean at all compared to a sprots bike.

**BNZ** · 31st August 2006, 09:40

Heavier wheels as well maybe? Something about a rotating mass having resistace to move yadi yada

Ouch, thought too hard

**sAsLEX** · 31st August 2006, 09:42

Your off track there I think with the weight issue, the reason cruisers dont lean in corners as much is they cant you start decking stuff out

I think the real reason lies more in the wheel base coupled with the tire and how that makes the bike turn

**Devil** · 31st August 2006, 09:46

Originally Posted by sAsLEX

Your off track there I think with the weight issue, the reason cruisers dont lean in corners as much is they cant you start decking stuff out

Follow a cruiser, even a small one like crashe's which doesn't have a long wheelbase and you'll see how much more you have to lean than she does at the same speed on the same corner.

Weight is a factor, but also where it's carried.

**McJim** · 31st August 2006, 09:50

The whole objective of lean is because of the combined vectors of gravity and centrifugal force acting on the bike. Since both of these vectors owe a lot to the weight and the weight distribution on the bike the key factors have to be it's mass and centre of gravity.

Travelling in a straight line the only lateral force is Gravity - hence the bike is upright. As the bike turns the centrifugal force comes in to play. The greater the mass/speed or tightness of the turn the greater the centrifugal force applied and the more lean required to maintain balance to ensure the bikes wheels point to 'virtual down' (being the combined direction of the 2 vectors of Gravity and Centrifugal Force)

That's the application of logic but doesn't seem to prove the fact - the heavier bike had LESS lean....not more.

**sAsLEX** · 31st August 2006, 09:50

Originally Posted by Devil

Follow a cruiser, even a small one like crashe's which doesn't have a long wheelbase and you'll see how much more you have to lean than she does at the same speed on the same corner.

Weight is a factor, but also where it's carried.

So a 300kg bloke on a r6 (would look silly but this is a mind exercise) would therefor ride like Crashe?

There is also the rake and trail of the forks which affect the interaction of the tire and its apparent radius with the road which would again have more affect than weight on its own.

So thats is a good point I jsut raised, your forks/ ride is more relaxed as is a cruisers than a GSXRCBRRRZX whatsit, maybe this is the answer to your question

**Masterchop** · 31st August 2006, 09:51

I have noticed a similar thing.
When following my mate on his Aprillia and me on Ducati, going the same speed (fairly quick) I lean alot more than him.

I put it down to wheel base and steering geometry,but only guessing.

**Drunken Monkey** · 31st August 2006, 09:54

Originally Posted by Big McJim

The whole objective of lean is because of the combined vectors of gravity and centrifugal force acting on the bike. ...

OMG! It always makes me laugh when someones tries to come accross all 'physics expert' and then says the word 'centrifugal'...

I would have to say "combined vectors of gravity and centrifugal force" is the best faux-science I've seen for a while. LOL, nice one!

Edit: For those who still don't get it: From Wikipedia-

Common misunderstandings
... should not be confused with centrifugal force. The centrifugal force is a fictitious force that arises from being in a rotating reference frame. To eliminate all such fictitious forces, one needs to be in a non-accelerating reference frame, i.e., in an inertial reference frame. Only then can one safely use Newton's laws of motion, such as F = ma....

**sAsLEX** · 31st August 2006, 09:54

Originally Posted by Big McJim

The whole objective of lean is because of the combined vectors of gravity and centrifugal force acting on the bike. Since both of these vectors owe a lot to the weight and the weight distribution on the bike the key factors have to be it's mass and centre of gravity.

Travelling in a straight line the only lateral force is Gravity - hence the bike is upright. As the bike turns the centrifugal force comes in to play. The greater the mass/speed or tightness of the turn the greater the centrifugal force applied and the more lean required to maintain balance to ensure the bikes wheels point to 'virtual down' (being the combined direction of the 2 vectors of Gravity and Centrifugal Force)

That's the application of logic but doesn't seem to prove the fact - the heavier bike had LESS lean....not more.

Originally Posted by wiki

Confusion and misconceptions

Centrifugal force can be a confusing term because it is used (or misused) in more than one instance, and because sloppy labeling can obscure which forces are acting upon which objects in a system (which is true for physics in general). When diagramming forces in a system, one must describe each object separately, attaching only those forces acting upon it (not forces that it exerts upon other objects).

One can avoid dealing with pseudo forces entirely by analyzing systems using inertial frames of reference for the physics; and when convenient, one simply maps to a rotating frame without forgetting about the frame rotation, as shown above. Such is standard practice in mechanics textbooks.

Because rotating frames are not vital for understanding mechanics, science teachers often de-emphasize the centrifugal forces that appear to exist in a rotating reference frame. However, in their zeal to stamp out the misunderstanding of the term in this one case, they may try to expunge it from the language entirely.

Try to avoid centrifugal force as the basis of an argument as it is a rectionary force to the Centripetal Accelleration and force one undergoes in cornering

**McJim** · 31st August 2006, 09:57

Originally Posted by Drunken Monkey

OMG! It always makes me laugh when someones tries to come accross all 'physics expert' and then says the word 'centrifugal'...

I would have to say "combined vectors of gravity and centrifugal force" is the best faux-science I've seen for a while. LOL, nice one!

That's cool cos I piss myself laughing when I see people using 3 letter acronyms!

Buwahahahaha

Now tell me my first post wasn't a troll.