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Discussion Starter · #1 ·
Out of curiosity, how does lowering a bike affect lean angle? Does the lowered center of gravity require less less angle in turns? It FEELS like I'm leaning more than the chicken strips would indicate.
 

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Found this, may prove interesting...

So how does the vertical position of the CG affect turning
performance?...

Well, to achieve a 1g lateral acceleration in a turn, one would
expect to have to lean the bike over to 45 deg from
the vertical. But to counter the gyroscopic forces one has to lean it
over even more. Below is a table showing the
lean angle required to achieve a 1g turn as a function of the bike's
vertical CG position, for a particular case, namely
my bike at 100kph.

% -------Results-------
% ZCG (m) Bank (deg)
% 0.0000 90.0000
% 0.1000 82.4798 ZCG - height above ground of CG
% 0.2000 65.2291 Bank - angle of lean of bike
% 0.3000 59.0005
% 0.4000 55.7331
% 0.5000 53.7108 Note : Ignoring Gyroscopic forces
% 0.6000 52.3332 gives a bank angle of 45 deg.
% 0.7000 51.3334
% 0.8000 50.5742 Radius of turn Tr = 78.65m
% 0.9000 49.9780 Time to 360 deg 1/O*2*pi = 17.79sec
% 1.0000 49.4973

Note: The only variables that affect this angle are the speed of the
bike (100kph/62mph) and the ratio of the mass of
the wheels to the bike (11% per wheel).

So one can see from this that lowering the bike's CG increases the
required lean angle for a particular turn, thus
reducing the bikes turning performance. Answering the initial
question.

But as we all know, it is not practical to steer a bike by shifting
one's weight, one has to counter-steer. The reason
why this works is again because of the gyroscopic forces, and one
neat trick called precession. What precession
means is that if you apply a moment to a gyroscope (counter steer on
your front wheel) your force applied will be
rotated through 90 deg in the direction of rotation. This means that
any turning force applied to your handle bars is
then applied to your bike, tipping it over in the opposite direction.
Note that the steering does not turn but the bike is
pushed over. This is then opposed by the gyroscopic force due to the
turning of the bike through the turn. You can
either stop applying the counter-steer at this point and use the
bike's mass to hold you in the turn, or hold the turn
with continual counter-steer thus reducing the bike's required lean
angle (interesting idea! don't try this at home
kids). So back to the initial question, a bike with a low CG will
require a larger force on the handle bars to turn it.

Now back to the inertia debate, a quick calculation of the force on
the handle bars to a achieve a rapid lean of the
bike (45 deg/s in one second - more than the average) taking into
account the inertia (guess) of the bike, gives a
force of about 41Nm (8kg - for a 0.5m handlebar). Probably a more
realistic value would be half of this.
Interestingly the righting force (gyroscopic) for the above 1g case
is 288Nm (58kg at the bars - obviously further
leaning is necessary).
 

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YO MAMA
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WOW brian:laughing

dave....when ever you lower a bike..you are TAKING AWAY ground clearance, more so on the lean angle side.

So when a bike is lower...you leaning it over will reduce the amount of clearance you have for cornering.

(Case in point) when I was riding carlos's lowered busa) I ACCIDENTALLY touched down his muffler in a turn..when I (to me barley leaned it over) so if you drop it...that's what will happen.

Dropping a bike is more advantagefull for drag racing...it help keeps the front down more.

hope this helped
 

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Discussion Starter · #4 ·
So, I have to lean further to corner at the same speed AND it seems you are leaning further than you really are due to both ground clearance AND steering force.

I think this explains the chicken strips while it seems I'm leaning.:thumbsup
 

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Y2KR1 said:
Found this, may prove interesting...

So how does the vertical position of the CG affect turning
performance?...

Well, to achieve a 1g lateral acceleration in a turn, one would
expect to have to lean the bike over to 45 deg from
the vertical. But to counter the gyroscopic forces one has to lean it
over even more. Below is a table showing the
lean angle required to achieve a 1g turn as a function of the bike's
vertical CG position, for a particular case, namely
my bike at 100kph.

% -------Results-------
% ZCG (m) Bank (deg)
% 0.0000 90.0000
% 0.1000 82.4798 ZCG - height above ground of CG
% 0.2000 65.2291 Bank - angle of lean of bike
% 0.3000 59.0005
% 0.4000 55.7331
% 0.5000 53.7108 Note : Ignoring Gyroscopic forces
% 0.6000 52.3332 gives a bank angle of 45 deg.
% 0.7000 51.3334
% 0.8000 50.5742 Radius of turn Tr = 78.65m
% 0.9000 49.9780 Time to 360 deg 1/O*2*pi = 17.79sec
% 1.0000 49.4973

Note: The only variables that affect this angle are the speed of the
bike (100kph/62mph) and the ratio of the mass of
the wheels to the bike (11% per wheel).

So one can see from this that lowering the bike's CG increases the
required lean angle for a particular turn, thus
reducing the bikes turning performance. Answering the initial
question.

But as we all know, it is not practical to steer a bike by shifting
one's weight, one has to counter-steer. The reason
why this works is again because of the gyroscopic forces, and one
neat trick called precession. What precession
means is that if you apply a moment to a gyroscope (counter steer on
your front wheel) your force applied will be
rotated through 90 deg in the direction of rotation. This means that
any turning force applied to your handle bars is
then applied to your bike, tipping it over in the opposite direction.
Note that the steering does not turn but the bike is
pushed over. This is then opposed by the gyroscopic force due to the
turning of the bike through the turn. You can
either stop applying the counter-steer at this point and use the
bike's mass to hold you in the turn, or hold the turn
with continual counter-steer thus reducing the bike's required lean
angle (interesting idea! don't try this at home
kids). So back to the initial question, a bike with a low CG will
require a larger force on the handle bars to turn it.

Now back to the inertia debate, a quick calculation of the force on
the handle bars to a achieve a rapid lean of the
bike (45 deg/s in one second - more than the average) taking into
account the inertia (guess) of the bike, gives a
force of about 41Nm (8kg - for a 0.5m handlebar). Probably a more
realistic value would be half of this.
Interestingly the righting force (gyroscopic) for the above 1g case
is 288Nm (58kg at the bars - obviously further
leaning is necessary).
you just can't simply say yes dave you are right or no dave you are not right all this science stuff is too much :jester just answer the question save the facts for later :rofl
 

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BusaDave said:
Out of curiosity, how does lowering a bike affect lean angle? Does the lowered center of gravity require less less angle in turns? It FEELS like I'm leaning more than the chicken strips would indicate.

hmmmmmmmmm. Remember the Gixxer incident back in March. IMO it's much much much much much easier to turn a bike that's higher and narrower than low and long.:mad :mad :helmet :D
 

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I can make my bike lean!
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Dave, simple solution......Let me test out your bike and I will give you the results of my finely tuned Seat of the Pants Motorcycle Handling Guage.
 

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Premium Member
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Also dave since the rear was lowered more than the front was it also change the angle of rake that your front forks were set at. Which will slow your lean a bit also. That is probably where you are noticing the most handling difference. You may want to order a set of moterheads 1.5" links instead of the 2" drop you have now. Thats what I have and mine handles pretty good. Plus my front is still at stock hieght. When I take it for that ride you offered me I'll let ya know how much different it feels from mine.

Oh i really think you may need to loosen that thing up a bit, it is really stiff. It didnt sag at all when I sat on it. and with my 215 lb ass on it, it should have :D
 

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N the other hand, the hgiher the CG, the less effective leaverage you have ot change direction and trun in quickly. THis is why dispite the advantage of a high CG, GP bikes try and get it lower for better acceleration and to transition into a turn quicker so they can brake later and accelerate longer.

Does a lighter bike also require less lean angle??? or is mass canceled out in the equqation???
 

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GsxrTony said:
You may want to order a set of moterheads 1.5" links instead of the 2" drop you have now.


Or buy my top triple clamp and lower the front.
I know on my bike I could really tell if the front wasn't low enough. It took two men and a boy to countersteer the thing.
 

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Discussion Starter · #12 ·
bluebusa60544 said:
Or buy my top triple clamp and lower the front.
I know on my bike I could really tell if the front wasn't low enough. It took two men and a boy to countersteer the thing.
Already got an adjustible triple tree!:) Thanks anyway.
 

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Discussion Starter · #13 ·
GsxrTony said:
Oh i really think you may need to loosen that thing up a bit, it is really stiff. It didnt sag at all when I sat on it. and with my 215 lb ass on it, it should have :D
I'm thinking that it's got too much preload. I don't know if that was done because it was lowered or if it came from the factory adjusted wrong. I've already messed with the compression and rebound. I have them set similar to my '01.

I'm going to have to look at this. It's a bit too firm and bouncy.
 

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Lovin this Twin
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Im definately not into the tech end of this But the other night on Crazys ride..... I followed you thru every one of the clover leafs.

You had a long ways to go before scrubbin off those chicken strips......... And Honestly if I can have time to watch what your doing thru a curve { cuz I suck at corners} I dont think you could lean much further unless the pace was picked up just a tad.

Whoa that just sounded like a critique! Not at all intended to be that way... Im just stating that from the back it looked like you had a long ways to go before any chicken strip was removed
 

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Michael said:


you didn't have to quote the whole thing again damnit!! :D :D :D :D :twofinger
:eek:t
Not all of us are postwhores (mr 1124):laughing
and know to delete text when replying with the "quote" option:twofinger :laughing

Brian
 

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Discussion Starter · #16 ·
HooliganZX10 said:

You had a long ways to go before scrubbin off those chicken strips......... And Honestly if I can have time to watch what your doing thru a curve { cuz I suck at corners} I dont think you could lean much further unless the pace was picked up just a tad.
I'm sure that's true. I have a LOT of changes with the new bike and I'm still trying to figure it out, along with the fact I didn't trust the new pavement.

I've got crazy power, different geometry, different suspension settings, and back to the stock tires. Also, I'm less comfortable on a group ride where I'm watching everyone else instead of being free to concentrate on my own stuff.

I'm not offended by the observations, but occasionally get tired of the "why do you need more power" comments. The best answer is, if you have to ask, you wouldn't understand.:D

I may never be a peg dragger and I may never be as fast as some but I try to ride smart, leave myself room for error, and be considerate of the traffic around me. Sometimes the ride is simply faster than I want to go! But I'm not generally too far behind!:twofinger

Besides, we need experienced back markers too!:thumbsup
 

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Lovin this Twin
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I hear ya Dave on never being a peg dragger, I will never be either..................... I really didnt mean it to sound like you were riding bad in any way it was just my opinion on your lean factor thats all.

And for the power thing if your referring to me making the comments................ Sorry..... 200 mph is insanity to me but if thats your thing God bless ya:evil :evil

With wheelie bars and a slick Id love to see what that turbo would do in the 1/4........... high 8's ?
 

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Discussion Starter · #18 ·
HooliganZX10 said:

And for the power thing if your referring to me making the comments................ Sorry..... 200 mph is insanity to me but if thats your thing God bless ya:evil :evil

With wheelie bars and a slick Id love to see what that turbo would do in the 1/4........... high 8's ?
Nah, I doubt it will ever see 200 with ME on it, but I can tell you that it will do 100 in second gear pretty darn fast. Or so I've been told anyway.:p A punch from around 5000 rpm in 3rd is wicked and a 6th gear roll-on begins to pull really hard around 120.

I'll lean it more over time. It's just strange that it feels more leaned that it really is compared to the '01 with the Michelins.
 
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