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Discussion Starter · #1 ·
Having spent decades dialing in suspensions for myself and others, I usually have some common baseline values that seem to be fairly universal. Then comes the Ducati... the baseline total sag is a little different.

First of all, let's make a couple of opinions of mine clear:

1 -- Setting baseline sag is just a starting point and the starting number perhaps isn't that important, but total suspension sag it is an important data-point to keep track of.
2 -- The forks especially have 5mm to 10mm stiction which needs to be averaged and minimized. To minimize: strategies include wiping the stanchions with a cloth soaked with silicon lube spray, eliminating or enlarging the dust seal, using low drag seals, low drag fluids, low drag bushings and low drag coatings on the stanchions. To average: when measuring the loaded compression of the forks push_down_let_up_measure, then lift_up_let_down_measure, and use the average of the two numbers.

Back to the point -- generally speaking the Ducati Superbikes for the track like a 40mm/30mm front/rear sag as a baseline for the track. This is per the many threads by Dan Kyle, and also the RS manual shows withing a few mm's the same number.

For most other bikes, R1, R6, RSV4, ZX10, the front suspension sag baseline is usually around the 35mm mark... 33, 34, 35, 36, those are the typical front sag numbers, and 40mm would be considered a very soft setting.

The stock 1198 forks are at 35mm on their softest setting for my weight, and they are way too harsh on all but the very smoothest of tracks, and it still doesn't seem ideal. Although it's excellent with a passenger, that doesn't count because the sag is not set with a passenger. So, 40mm seems like a sweet spot for me, and I have confirmed this on many tracks, riding in the canyons, etc. Feels like a 35mm set up on many other bikes.

So, what's the scoop? Why is this?
 

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I'm no suspension expert but comparing sag numbers between different bikes doesn't make sense to me. If you'd get a softer spring and use more preload you'd probably get a less harsh ride an less sag.

On the other hand I always heard Ducatis are undersprung and overdamped. Maybe that fits your experience?
 

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Ducati's are typically oversprung from factory compared to most other bikes. Although your sag numbers don't sound quite right (to me).
When we raced the 916 and 998 (with both Showa and Ohlins) we would typically run our loaded sag 25-30mm FR and 20-25mm RR. I have a 999 running these same numbers as well. Typically we would run OEM monoposto RR springs and 9.5, 10 or 11Nm fronts.
 

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could the bike weight play a role in the sag numbers? arent the ducatis in general lighter than japanese by 10-20kgr?
 

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Discussion Starter · #7 ·
I don't have any experience and dealings with the 916-748-996-998 variety whatsoever. Anything that I have done with the 749-999-848-1098-1198 has been over the past year or so.

However, the 998RS02 Shop Manual and the 999RS04 Shop Manual both show 37mm standard baseline front and 27mm rear...
 

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Spring rates play a huge part in your set up. If you need to put more than 5 or 6 turns of pre-load on your springs, you probably need to go to a higher rate spring. Your static sag and free sag numbers need to be within certain parameters in order to allow the suspension to function correctly. For example, if one were to set his or her rear static sag number, and take the rider weight off the bike to find the rear topping out hard, you need a stiffer spring. because you are forced to put to much pre-load on to soft of a spring to get the desired static sag number. The ideal spring weight would allow the user to set the static sag, and have a free sag of 4 to 6 mm, or a very soft top-out at the rear. Adjusting the compression and rebound damping is a complete waste of time until the you have a proper spring rate properly preloaded at both ends of the bike... You will find most sport oriented motorcycles are delivered to dealers sprung for 140 to160 lb riders. most stock fork oil levels are on the high side. most rear suspension linkage has a ridiculous amount of progression. This lets the bike feel plush on the test ride, while keeping the thing from sacking out with 2 up or an obese American. Because the idea is to sell the bike. The potential buyer could be a NFL linebacker or a 95lb girl . Those mechanics you see in the background of magazine tests are busy swapping springs and setting perloads for the individual test riders. And yes, Ducati superbike suspension is valved more aggressively than Japanese sport bikes. And a Ferrari F50 rides a tiny bit harsh compared to a Toyota Corolla... Why? When you really put your bike in a corner, or go all mad on the brakes,you need to have some suspension travel leftover for bump compliance or you are crashing. A real sport bike builder is willing to give up some straight line plush to achieve this
 

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Discussion Starter · #9 · (Edited)
Hmmm, thank you for adding to the thread, and I agree with you. Please don't take any offense, but you don't sound like a suspension expert, stating some basic ideas...
 

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Discussion Starter · #10 ·
I didn't make this clear... We're not discussing stock suspensions from the factory, we're not talking about deficiencies of how dealership bikes are set up and how magazine testers assess anything, we're not talking about what the bike feels like on track days or that they are spring for 150 lb riders, this is a much different topic all together.

What we are discussing is competitive and proven track setups of race bikes.
 

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To be clear and be speaking the same language; static sag is the amount of deflection with rider (wearing gear, in riding position, ie hands on the bars feet on pegs elbows bent ect) on board. Free sag, the amount of deflection without rider. Pre-load is how much one needs to compress the spring to achieve proper sag. Valving usually refers to the shim stack on the pistons that affect high speed compression and rebound action. Ride height would be the bikes attitude in relation to the ground, completely independent of sag. (sag must be within parameters before one dicks with ride height). Spring weight refers to the amount of force needed to deflect a given spring. Suspension springs are available in 0.5 nm increments.
 

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I didn't make this clear... We're not discussing stock suspensions from the factory, we're not talking about deficiencies of how dealership bikes are set up and how magazine testers assess anything, we're not talking about what the bike feels like on track days or that they are spring for 150 lb riders, this is a much different topic all together.

What we are discussing is competitive and proven track setups of race bikes.
Oh, my bad... i thought you were talking about suspension set up for getting a conference inspiring feel form a motorcycle so one could lower his/her lap times.. sorry..
For me, set up changes from track to track, from tire to tire, condition of said tire, from morning to afternoon. As im constantly looking for a faster lap and better tire life. The only constant is my spring rates, and usually my sag settings. I've only been club racing sense i was 9. I'm an idiot .
 

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Discussion Starter · #13 · (Edited)
To be clear and be speaking the same language; static sag is the amount of deflection with rider (wearing gear, in riding position, ie hands on the bars feet on pegs elbows bent ect) on board. Free sag, the amount of deflection without rider. Pre-load is how much one needs to compress the spring to achieve proper sag. Valving usually refers to the shim stack on the pistons that affect high speed compression and rebound action. Ride height would be the bikes attitude in relation to the ground, completely independent of sag. (sag must be within parameters before one dicks with ride height). Spring weight refers to the amount of force needed to deflect a given spring. Suspension springs are available in 0.5 nm increments.
Ductard,

You're correct, no arguments, but yes, off topic.

Lot of suspension basics threads... here's a few:

http://www.ducati.org/forums/technical/1490-1098-preload-too-high.html
Suspension 101 basics. - Ducati.ms - The Ultimate Ducati Forum

... and they mostly agree with you I'm sure.

I think the answer to the question lies in that most bikes, especially the i4... have the venter of mass located forward and fairly high also... the Ducati more rearward with the Vertical Cylinder and lower down with the Horizontal cylinder. That's speculation on my part, so that's the question I'd like to understand more.
 

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Discussion Starter · #14 ·
Oh, my bad... i thought you were talking about suspension set up for getting a conference inspiring feel form a motorcycle so one could lower his/her lap times.. sorry..
For me, set up changes from track to track, from tire to tire, condition of said tire, from morning to afternoon. As im constantly looking for a faster lap and better tire life. The only constant is my spring rates, and usually my sag settings. I've only been club racing sense i was 9. I'm an idiot .
Exactly... We're actually only talking about baseline sag settings in general.
 

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Discussion Starter · #15 ·
Although your sag numbers don't sound quite right (to me).
I know what you mean... but they are not exactly my numbers, but I have adapted them recently based on the overwhelming evidence of how they are set up at the highest level of competition and also based on Dan Kyle's very specific baseline recommendations.

The only time they seemed to be challenged is by the "I tried that and bottomed out so I reduced the sag" crowd and that immediately tells me they are likely doing this wrong. That's another conversation.

I probably should have started out with my thoughts on this but I wanted to get some other opinions... that the L-twin engine center of mass compared to i-4... meaning if we are to plot well developed suspension settings from WSBK from say 2003-2012... that the Ducati settings would be let's say 35-41 front sag with the average of 37/38 and the i4 would be 31-37 with the average of 33/34 ... just making up numbers here based on my impressions from various sources including and foremost from the evidence presented, but you get the point.
 

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I think the answer to the question lies in that most bikes, especially the i4... have the venter of mass located forward and fairly high also... the Ducati more rearward with the Vertical Cylinder and lower down with the Horizontal cylinder. That's speculation on my part, so that's the question I'd like to understand more.[/QUOTE]

I believe you're referring to weight bias.. ive not actually weighed any bike but my own 998 chassis /1198 motor track bike. It is 30% rear and70% front. This changes slightly with ride height adjustments that may happen 3 times at one track /practice day. This is pretty close to manufacturer specs I've seen for Yamaha/ Suzuki /Honda sport bikes. But my bike is a combination of stuff, longer swingarm shorter offset triple clamps, steep rake setting...And although the motor mounting points are the same , the casting of the 1198 case makes it sit further forward and lower than the 998 motor... no idea how much any of that comes into play. I do know that race teams are always looking for a way for more front bias. Obviously this would affect the amount of pre-load needed to achieve a desired sag number. My sag numbers come from Stig Petterson, factory Ohlins tech and suspension guru for pretty much every race team that uses Ohlins. Yes, you can glimpse him milling around the moto gp pits in a some pre race propaganda footie..His advice to me was stick to these preload numbers and change compression /rebound settings, ride height , fork oil levels,and valving to overcome setup shortcommings.. but im just a bumbleing club guy..He may have completely different advice for others
 

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Discussion Starter · #17 ·
I believe you're referring to weight bias.. ive not actually weighed any bike but my own 998 chassis /1198 motor track bike. It is 30% rear and70% front. This changes slightly with ride height adjustments that may happen 3 times at one track /practice day. This is pretty close to manufacturer specs I've seen for Yamaha/ Suzuki /Honda sport bikes. But my bike is a combination of stuff, longer swingarm shorter offset triple clamps, steep rake setting...And although the motor mounting points are the same , the casting of the 1198 case makes it sit further forward and lower than the 998 motor... no idea how much any of that comes into play. I do know that race teams are always looking for a way for more front bias. Obviously this would affect the amount of pre-load needed to achieve a desired sag number. My sag numbers come from Stig Petterson, factory Ohlins tech and suspension guru for pretty much every race team that uses Ohlins. Yes, you can glimpse him milling around the moto gp pits in a some pre race propaganda footie..His advice to me was stick to these preload numbers and change compression /rebound settings, ride height , fork oil levels,and valving to overcome setup shortcommings.. but im just a bumbleing club guy..He may have completely different advice for others
Tuned? Is that you???

30% - 70%? Wow. All yours pal, I'm out.
 

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Ouch....Do i really sound like tuned? You could have just kicked me in the balls... You didn't have to get all mean.
I'm honestly just one of those guys thats always messing with stuff... and taking notes.. ive really done a lot of laps and crashed a lot of shit to learn what little i know.. i am only trying to share some knowledge.
 

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Excellent analytics DHarsay!, I wish I had spent more time learning about suspensions. My old 07 GSXR750 was a tank, but held its corner speed very well. With my 1198 I copied what was popular; 30mm offset triples, flat rear link and modified shock, and it cornered way better than my gixxer, but the wheelie tendencies on corner exits got me worried, so I never exceeded my lap times from my past bike. At the end of the season, I learned to like the wheelies, even got passed at the finish line while on the back tire, from a BMW rider haha!
I also like how this thread hasn't been derailed by some self-proclaimed expert, and that opinions are being 'shared' rather than torn apart. Keep up the good work!
 
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