Centrifugal forces

[spamanglenn]

I read rapid and spoke to geoff ware about a 600,750 and 1000 cc gsxr test at phillip island.Even though he had his project gsxr1000 there with light wheels etc,he said the 600 turned much quicker.After chewing on it and knowing each bike weighs about the same,I finally understand why.Its the centrifugal force of the engines crankshaft.As a 1000 cc has bigger pistons and a longer stroke than a 600,its crank is heavier.Therefore just like heavy motorcycle wheels don,t like fast changes of direction without a lot of effort nor do crankshaft at 10-12000rpm plus.A racer mentioned to me that they often use this force by using high revs in a given corner to help hold the bikes lean angle.I know yamaha reversed the rotation of their engine to change the characteristics of the force and optimised the bike around it.Thats what i like about bikes,theres always something to learn. Glenn the Spa Man<i></i>

[ressac]

Don't you mean gyroscopic forces? No such thing as centirfugal force. The centrifugal observation is an observation of a LACK of centripetal force to hold things in circular motion.

Anyway, the crank on an inline 4 has a lateral axis, ie across the bike, not longitudinally like a car. So, there is no impact on the gyroscopic nature of the spinning crank when it is tilted in line with that axis.

I'd say there are a lot of other things that increase the tip in speed, or roll rate of the bike. The main one that comes to mind is the fork angle. There are also other geometries regarding the fork location forward of the front wheel axle. Further, whilst the bikes might weigh the same, the weight may be carried differently, ie in different height from the ground, or forward or backward from the centre. Suspension can also affect how a bike tips in. The last thing I can think of is that the gixxer thou may have been entering the corner a little quicker than the 600, and thus give the impression of tipping in slower because the corner is a little more rushed on the 1000 than on the 600. -385-
XOCET<i></i>

[BUSGO]

You are correct there Reesac about the longitudinal force.
That is why BMW have moved to across the frame inline bike engines.
However they have the upper hand with suspension with the mono front end on the K1200s. The setup retains the same geometric shape regardless of the suspension compression.

The BMW K1200s and r are the best competition for the busa but are twice the cost.

Rgds BUSGO

"TAKE MY ADVICE"
I'm not using it anyway!<i></i>

[spamanglenn]

So why did yamaha reverse the direction of their engines rotation and state that it improved manouverability but reduce straightline stability in moto gp.If the crankshaft is parallel to the axles and the stroke has a swept diameter of at least 100mm and its spinning at high rpm,how would this differ from a wheel at a few hundred rpm?.One has a smaller radius but high rpm,one has a large radius and lower rpm.I may have the terminology wrong but there is definately a force there.Rotational inertia upon acceleration and deceleration is also quite real.Don,t you remember revving your engine in your car in nuetral.As you revved it the motor leant to one side and mildly rocked the car.I,m open to being wrong though.Perhaps if you could measure the effort required to vary the angle of lean at a predetermined speed of change of angle on a stationary bike.Then rev it in nuetral and repeat the test.If there is more effort to acheive the change in lean at the same speed,gyrocopic force is having an effect.If the effort required is the same,engine gyroscopic force has no effect on the bikes change in direction response.I suppose 530 to 520 chain sets is another significant weight moving at high speed as well.Its all interesting. <i></i>

[Blackzook]

I think the need lighter wheels and better brakes. PM me for a price Bruce
N2O no laughing matter
f*** nos I've got Velocity
<i></i>

[BUSGO]

Sorry Glenn, I should have said that your are correct as well with regards to the centrifical force of the engine.
That is why BMW also developed the torsion bar on the drive shaft of their bikes in the mid 90's.
My old BMW K75 was a whole new learning curve, or should I say Leaning curve, when it came to cornering.

I wonder how the 2.3litre Rocket III handles the force for cornering.


@Bruce, if you study your bunny, you will notice that the pancake is tilted forward and his ears are layed back to counteract the force during forward momentum.

Rgds BUSGO

"TAKE MY ADVICE"
I'm not using it anyway!<i></i>

[Blackzook]

For fucks sake Ray his ears are compensated by his forward facing wiskers, causing drag lowering his attack angle. So obvious even an idiot can see that. His head is also leaning left which is caused by the earth rotating on its polar axis. Please do your research before making silly comments. Bruce
N2O no laughing matter
f*** nos I've got Velocity
<i></i>

[spamanglenn]

Its all interesting and riding bikes of different engine configuration helps you filter out the differences.Twins change direction quite well and power down really well.I,ve never had a better connection between throttle and rear tyre than my brothers tlr.I,ll try to make it to coffee night tonight so we can discuss the centre of mass of a doughnut. <i></i>

[AzaVic]

Blackzook, I dont think you have taken into account the gain he would get from his aerodynamic shape, yeah maybe he is a bit podgey, a little wide, perhaps somewhat heavy, but hey, so is the Busa and it is ment to be aerodynamic <i></i>

[Busdriver]

See my post in "Hanging Off"

It will clear this all up for you.

<i></i>

[simmo]

That is no Bunny thats PAN-themancake in his younger days

Cheers Robert
Aren't all Busas Copper & Plated, the others are just all very poor slow ugly copies !!!!!<i></i>

[pan]

Bruce, you got it all wrong. The pancake is good, just rip out the bunny and put in a bigger and more powerful one

(Simmo of course would somehow add bling to match that ugly brown/copper coloured rabbit coat) <i></i>

[kawasuki]

Just wondering why my back wheel turns faster than my front wheel, Bruce u there? We are on about the same level mate. Cheers,
Kawasuki<i></i>

[bear]

Geez, I started reading this thread thinking I might learn something...

[RaZ]

mm, well from the top of it I did :) all friendly like back in the day :)