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Old May 6th, 2012, 08:37 PM   #1
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Understanding Chassis a little more "part deux"

I wanted to write this for you guys as I receive many questions regarding the differences when you make modifications to your chassis, from adjusting the stock parts to full chassis modifications and installing aftermarket performance chassis parts. What I am writing here for you guys is showing the differences between the stock set up of my bike to the currently modified position. Though the actual modifications will vary with everyone and every bike, the following will give you a basic idea on how your bike will change with modifications to your bike's chassis and suspension. Remember, chassis AND suspension are DIFFERENT, and should be treated as such. I will not be putting suspension adjustments, as everyone's settings will be different due to tires, pressure, feel, rider, weight, aggression, etc. The only suspension setting I will list is SAG, as it tends to relate to chassis as much as suspension.


When I bought my '03 999, aside from the full system, it was virtually stock. At the time, the only thing I did was set the preload, rebound and compression for street riding(I have my track bike for being stupid). The bike handled OK at best, and I knew I would have to make changes immediately. Below are the stock numbers of the bike, out of the crate. Keep in mind, my bikes' fore/aft position was in the middle, so the weight bias was closer to 50.3%/49.7%. The rake position was set at 24.5, making the trail at 97mm.


Rake 23,5 - 24,5
Trail 91 - 97 mm
Swingarm Length 486mm
Swingarm Angle 9.2
Wheelbase 1420 mm
Weight Distribution 50.7% front/49.3% rear Monoposto at the front of the fore/aft position


Knowing the basic numbers(and that it wasn't touched before me), the first thing I did was brake out my handy dandy ride height tool, knowing that a basic improvement to the bike is simply by raising the rear ride height. This will reduce the rake angle and trail numbers, however apply more weight to the front of the bike so you won't lose any feel of the front end. The benefits of course is the faster steering of the bike, with less force needed to initiate the turn. So being a svelt 6' & 180lbs without gear, I tend to like a taller bike. I raised the rear up 25mm(It took several set & rides to determine where I was comfortable), but I was kind of cheating as I already had my numbers from my 996. I also raised the front end by increasing fork length from 705mm to 710mm, returning some of the trail lost by the rear ride height increase. The biggest benefit is the CofG being raised, giving the ability to turn in and transition faster. The biggest misconception is that lowering the bike will make the bike turn faster, which could not be any farther from the truth. I changed my rear sprocket by 2, then increased the swingarm length by approximately 19mm. So the following is the numbers after my initial set up.


Rake 23,6
Trail 92.1mm
Swingarm Length 505mm
Swingarm Angle 10.9
Wheelbase 1433 mm
Weight Distribution 50.77% front 49.23% rear


Notice the substantial increase in swingarm angle, even though the length was increased a full 19mm. When you raise the front, this increases the angle along with the rear ride height being increased. The effect to this is the weight bias being sent backward a bit, though the rear ride height made more than enough of a change to give a net forward increase in bias %.


The next step was to add our adjustable triple clamps to my 999. Since I wanted to play around I decided to make some minor changes to fork length and add the triples(27mm). If you are asking yourself “Why 27mm?” Simple, the previous trail numbers were too low, so I wanted to fix it in the way it should be. Lesser offsets would work fine, just not as well, remember trail is the “most” important factor in a bikes' geometry, and my analogy with Ducati's is, “you don't put a bandaid on a cut that needs stitches.”


I swapped the forks to a set of 1198 units I received for a great price, and installed them at the same time. When I added these units, I had the fork length measured at 695mm. I did this only to see what I was going to feel with the rake being further reduced, while increasing my trail through the triples. I also knew with the shorter wheelbase, I would not have to lean the bike over as far, plus the higher CofG combination, yielding a faster transition overall. What I found was better feel up front, (along with the previous sentences' statement) but noticed some occasional minor oversteer. It was reduced with some added preload and compression, but not entirely cured. What I found out was that the front tire was just rubbing on the front V-chin of the bodywork when loaded up. The extra preload and compression kept the front from compressing as much. FYI, the front was a bit soft from the beginning. I knew I had to make some changes, but here is the updated numbers below.


Rake 23,4
Trail 100.8mm
Swingarm Length 505mm
Swingarm Angle 10.8
Wheelbase 1423 mm
Weight Distribution 51.17% front 48.83% rear


Fast forwarding to today. I've decided to set my bike up the way it is supposed to be, using my triple clamps and putting the bike in the “zone”, for the best possibility to steer fast, great feedback, stability and roadholding capabilities. I decided to keep the 27mm offset, but changed the steering head caster to the 23.5 position. When putting the forks back on, I moved the fork length up to a full 715mm. This gave me the needed clearance at the V-chin, so there should be no rubbing issues when loading the front. Here are the numbers for the latest iteration.


Rake 23,1
Trail 99.2mm
Swingarm Length 505mm
Swingarm Angle 12
Wheelbase 1430.5 mm
Weight Distribution 51.18% front 48.82% rear


I rechecked my work to make sure everything is TQ'd properly, however I ran out of time, as my kids made me jump in the pool(It was 90, after all), and I need to finish putting her back together. I should have her back together tomorrow and will give yo my subjective opinion shortly. By the way, when you factor in the weight loss of the exhaust(8lbs), the weight bias changes from what I have listed to 52.87%front/47.13%rear.


Feel free to throw your thoughts and questions out there. I wrote this timeline of chassis solely for you to observe how changes you make to a bike create a result. This was simply a cause and affect write up. Have fun with it, especially the guys that ask “what if I add this?” or “what if I change that?”.
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Objective Theorem:
Understanding Chassis a little more
Subjective Application:
Understanding Chassis a little more "part deux"

Last edited by 1fast750ss; May 7th, 2012 at 08:13 AM.
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Old May 7th, 2012, 12:28 PM   #2
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Do you have a magic wand that will instantly make my 848 track corners like it's on rails and be very telepathic?


Oh ya..... that's right....Its call a 1199 Panigale!
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Old May 7th, 2012, 01:58 PM   #3
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Quote:
Originally Posted by STOPPIE View Post
Do you have a magic wand that will instantly make my 848 track corners like it's on rails and be very telepathic?


Oh ya..... that's right....Its call a 1199 Panigale!
It may not be a wand, but stop by and we'll get your bike to corner like it had "reading Railroad" painted on the side.
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Objective Theorem:
Understanding Chassis a little more
Subjective Application:
Understanding Chassis a little more "part deux"
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Old May 7th, 2012, 02:44 PM   #4
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Update

Put her back together this morning and just arrived back from a little test ride.

Though I haven't twisted in anger yet(won't on city streets) I will add this:

What I will say about my initial ride is that the bike feels 20lbs lighter. I say feels, as it is a subjective observation.

Where the feeling is coming from is initial turn in. It takes much less force to initiate a turn. As I enter the turn, there is no sign of over/under-steer, and I feel every movement as if the bars are on the tires. As explained before, the higher CofG makes turn in faster, but the shorter wheelbase requires less lean angle, so you are transferring much faster than before. These attributes combined with the dramatically reduced rake makes for a very fun twisty killer, as you have to work less to get the result versus before.

The benefits of the reduced rake, combined with the extra trail has transformed the bike into knowing where it is at all times. Almost telepathic.

The increased swingarm angle(I adjusted preload, compression & rebound) keeps the rear tire on the ground, and makes the bike want to go forward....and fast. Grip is just right, but there's no feeling of weight transference to the rear, as the bike almost feels as if it just stays level at all times.

Speaking of level. The bike feels level, literally. This means less weight on my wrists, though it does feel longer to the tank than before. This is due to the rake change, so expected.

In conclusion, the bike is comfortable and confident feeling, holds the road very well, turns very fast, with little effort, and exits on any line you pick(doesn't move from that line unless you want to). Changing lines midcorner was a simple task, unlike before.

I hope this helps you guys as to see the differences chassis and suspension adjustments can make, both objectively and subjectively. If you have any questions, feel free to call me or email me at anytime(well, reasonable time anyway).

Ciao
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Objective Theorem:
Understanding Chassis a little more
Subjective Application:
Understanding Chassis a little more "part deux"

Last edited by 1fast750ss; June 20th, 2012 at 08:52 AM.
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Old May 7th, 2012, 04:13 PM   #5
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Quote:
Originally Posted by 1fast750ss View Post
It may not be a wand, but stop by and we'll get your bike to corner like it had "reading Railroad" painted on the side.
I wish man; but it's gonna cost me a couple thousand dollars and that just seems silly to spend on a bike that SHOULD have handled correctly for the original price.

But thanks man.

I'll do what I can with what I have an if all goes well with personal reviews on the Pani I'll order one of those and cut my losses.

I will say i do like scaring the crap out of peeps when I pass'em with my new Termi's on....

And if you did house calls Brian we'd go to Mortons for dinner and the strip club afterwards LOL
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Last edited by STOPPIE; May 7th, 2012 at 04:16 PM.
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Old May 7th, 2012, 08:55 PM   #6
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Well, that depends on where you live. Morton's and the nudie bar? hmm.....LOL!

Quote:
Originally Posted by STOPPIE View Post
I wish man; but it's gonna cost me a couple thousand dollars and that just seems silly to spend on a bike that SHOULD have handled correctly for the original price.

But thanks man.

I'll do what I can with what I have an if all goes well with personal reviews on the Pani I'll order one of those and cut my losses.

I will say i do like scaring the crap out of peeps when I pass'em with my new Termi's on....

And if you did house calls Brian we'd go to Mortons for dinner and the strip club afterwards LOL
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Objective Theorem:
Understanding Chassis a little more
Subjective Application:
Understanding Chassis a little more "part deux"
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Old May 8th, 2012, 06:51 AM   #7
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Hi Brian,

Great article!

I'm also going around the geometry of my bike!

My bike is a 1098S track preped, with a tuned engine. The chassis has a 26mm offset triple.

I'm having a problem with wobble on the straights at WOT even in 6th.

One of the causes of my problem and a thing to watch when putting a lower offset triple is the wheelbase, as each millimetre of offset you take you roughly get out the same in the wheelbase. And that causes all the sort problems stability wise.
The problem is worse in the 1098 bike as the swing arm doesn't have the range of the 999 bikes. I'm at the longest position and have 505mm of swingarm length, that with a brutal engine, get's me the wobble.

Other cause that i will study in the next track day is a COG height, high in my case, the forks are flushed with the triples, and coupled with a very high speed, acceleration track like Estoril, this might be another cause for the wobble.

Here is a video of a bike with the same problem, mine is a little worse, but you get the point.


After the trackday i will have a idea of the problem.

I'm already considering a SF swingarm as will get me the lost wheelbase, and give more front weight.

If you have more solutions for me to try...

Last edited by desmo_pt; May 10th, 2012 at 01:26 AM.
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Old May 8th, 2012, 07:41 AM   #8
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Well, that doesn't look so fun on the straights.... lol
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Old May 8th, 2012, 07:48 AM   #9
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Well, that doesn't look so fun on the straights.... lol
Is really scary, on the big straight you just grind you teeth and go for it.

In the back straight with the kink i can't manage it. For you to see i can't be faster with the 1098 as a was with my 748R...
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Old May 8th, 2012, 07:49 AM   #10
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26mm is a ridiculously small amount of offset. Why not 28mm and eccentric head bearings to change the rake to 23.5 degrees? You may want to turn your damper in a few clicks...
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