Rear ride height adjustment

baggerman · Jul 17, 2023

I know somewhere it's posted the rear ride height change per turn on the TTX shock eyelet but I can't find it. Thanks in advance for the help.

mattinrsm · Jul 17, 2023

One turn is one mm of shock length which translates to about two mm of ride height.

baggerman · Jul 18, 2023

Thanks. I went ahead and raised the rear 6 turns which gave me 14 mm on the SF which has a 20mm longer swingarm. It moved the swingarm pivot up about 5mm. Too hot here to ride unless one starts early. So I won't know if I got what I want until tomorrow. I have another question. How far can I raise the forks before I start hitting the radiator? I'm down about 40 mm from the top of the fork nut, 3 lines showing.

RickD996 · Jul 18, 2023

baggerman said:
Thanks. I went ahead and raised the rear 6 turns which gave me 14 mm on the SF which has a 20mm longer swingarm. It moved the swingarm pivot up about 5mm. Too hot here to ride unless one starts early. So I won't know if I got what I want until tomorrow. I have another question. How far can I raise the forks before I start hitting the radiator? I'm down about 40 mm from the top of the fork nut, 3 lines showing.

What are you trying to achieve?
Have you adjusted the shock length, or the swingarm pivot?

SuperDomestique · Jul 18, 2023

RickD996 said:
What are you trying to achieve?

I’m guessing instability… 40 mm down the forks and up 14 in the back sounds like a handful. But sounds par for the course for some riding like a 17/39 drivetrain

baggerman · Jul 18, 2023

RickD996 said:
What are you trying to achieve?
Have you adjusted the shock length, or the swingarm pivot?

I adjusted the rear ride height up 14 mm which moves the swingarm pivot up (you're pivoting arround the shock eyelet). As far as instability I doubt it. The ability to readily change lines mid-corner is my aim. I've added anti-squat which will help keep the front end down and help any tendency to ride wide at the exits. The real problem is the SF is really long, 20mm longer than a panigale which I readily feel. I have several other ducati's that handle better. So at some point I'll change to a panigale swingarm. And that's 17/36 gearing.

SuperDomestique · Jul 18, 2023

baggerman said:
I adjusted the rear ride height up 14 mm which moves the swingarm pivot up (you're pivoting arround the shock eyelet). As far as instability I doubt it. The ability to readily change lines mid-corner is my aim. I've added anti-squat which will help keep the front end down and help any tendency to ride wide at the exits. The real problem is the SF is really long, 20mm longer than a panigale which I readily feel. I have several other ducati's that handle better. So at some point I'll change to a panigale swingarm. And that's 17/36 gearing.

You do realize that you effectively negate this increased anti-squat with the 17/36t sprockets?

cl955 · Jul 18, 2023

Swinging arm pivot is the one off the back of the engine and is not affected by preload or shock length.
The rear geometry is affected, but not the SAP.
Sorry to be pedantic.

RickD996 · Jul 18, 2023

baggerman said:
I adjusted the rear ride height up 14 mm which moves the swingarm pivot up (you're pivoting arround the shock eyelet). As far as instability I doubt it. The ability to readily change lines mid-corner is my aim. I've added anti-squat which will help keep the front end down and help any tendency to ride wide at the exits. The real problem is the SF is really long, 20mm longer than a panigale which I readily feel. I have several other ducati's that handle better. So at some point I'll change to a panigale swingarm. And that's 17/36 gearing.

Interesting to see how you get along with the changes. If you don't get the desired handling changes, try going the other way (lift front, lower rear), just for comparison.
But, yes, you've adjusted ride height, not the swingarm pivot.

SBK-SP · Jul 19, 2023

cl955 said:
Swinging arm pivot is the one off the back of the engine and is not affected by preload or shock length.
The rear geometry is affected, but not the SAP.
Sorry to be pedantic.

Yes, but the drive sprocket diameters, especially the front, do affect the SAP angle and thusly the anti-squat.

RickD996 · Jul 19, 2023

SBK-SP said:
Yes, but the drive sprocket diameters, especially the front, do affect the SAP angle and thusly the anti-squat.

no they don't. You can't adjust the 'SAP angle'

Swingarm pivot is a point. It can be adjusted, with different swingarm pivot bolts.

Swingarm angle can be altered. By adjusting the ride height, wheel size, swingarm pivot or hub position. Which, amongst other things, does alter the angle of swingarm thrust

There is an effect from chain pull, but I'm not sure how great it is vs swingarm thrust direction.

The wheelbase, and due to eccentric hub, and ride height, may change when you swap sprockets. But, this can be counteracted by changing the length of the chain.

baggerman · Jul 19, 2023

SuperDomestique said:
I’m guessing instability… 40 mm down the forks and up 14 in the back sounds like a handful. But sounds par for the course for some riding like a 17/39 drivetrain

My english to metric converter went haywire (I'm old and my mind is feeble). That was .400 inch or 10 mm on the fork.

SBK-SP · Jul 19, 2023

RickD996 said:
no they don't. You can't adjust the 'SAP angle'

Swingarm pivot is a point. It can be adjusted, with different swingarm pivot bolts.

Swingarm angle can be altered. By adjusting the ride height, wheel size, swingarm pivot or hub position. Which, amongst other things, does alter the angle of swingarm thrust

There is an effect from chain pull, but I'm not sure how great it is vs swingarm thrust direction.

The wheelbase, and due to eccentric hub, and ride height, may change when you swap sprockets. But, this can be counteracted by changing the length of the chain.

Yes duh! I meant the anti squat associated with the chain pull angle. The actual SAP/thrust angle applied is set by the actual pivot location. I should have been more specific in my post!

RickD996 · Jul 19, 2023

baggerman said:
My english to metric converter went haywire (I'm old and my mind is feeble). That was .400 inch or 10 mm on the fork.

I love the oxymoron that is decimalising imperial measurements

baggerman · Jul 19, 2023

RickD996 said:
Interesting to see how you get along with the changes. If you don't get the desired handling changes, try going the other way (lift front, lower rear), just for comparison.
But, yes, you've adjusted ride height, not the swingarm pivot.

Adjusting the ride height moves the swingarm pivot one of those geometry things. Do one get the other. I note that ducati moved the pivot up 4mm on the most recent panigale. Raising the back also moves the pivot up (motor moves higher). So my 14 mm up gave about 5 mm up at the pivot. CG would move up relative to the late panigales where only the pivot was changed. I still want to raise the fork tubes by 5mm more but will have to measure everything to see if I'm getting the wheel onto the radiator.

SuperDomestique · Jul 19, 2023

baggerman said:
Adjusting the ride height moves the swingarm pivot one of those geometry things. Do one get the other. I note that ducati moved the pivot up 4mm on the most recent panigale. Raising the back also moves the pivot up (motor moves higher). So my 14 mm up gave about 5 mm up at the pivot. CG would move up relative to the late panigales where only the pivot was changed. I still want to raise the fork tubes by 5mm more but will have to measure everything to see if I'm getting the wheel onto the radiator.

I think what people are saying is that the SWINGARM PIVOT is a static point and datum'd to the engine case. Anti-squat is the the angular force exerted by drivetrain-suspension geometries.

The pivot may move relative to the ground when moving suspension around, but the actual point stays the same (unless you have a V4R) since it's relative to the engine case/output shaft. Lowering the front forks through the triple has no effect on anti-squat.

baggerman · Jul 20, 2023

SuperDomestique said:
I think what people are saying is that the SWINGARM PIVOT is a static point and datum'd to the engine case. Anti-squat is the the angular force exerted by drivetrain-suspension geometries.

The pivot may move relative to the ground when moving suspension around, but the actual point stays the same (unless you have a V4R) since it's relative to the engine case/output shaft. Lowering the front forks through the triple has no effect on anti-squat.

Anti-squat is a function of swingarm angle. Moving the rear axle down relative to the swingarm pivot increases anti-squat so raising the rear increases anti-squat just as moving the swingarm pivot up increases anti-squat. I'm raising the forks to shorten the trail. So my changes increase anti-squat, changes the rake (head moves down about 10 mm rear is up 14 mm so about 1 degree less) and shortens the trail. Ain't my first rodeo. In reality I'm looking for a pattern on the tires. When the rear is fully scrubbed I want to see about 4 to 5 mm of front chicken strips on the front. Not necessarily the best race set-up but the set-up I want on a street bike because it increases agility. Helps one dodge rocks, gravel, pucked antifreeze, logs, skip squirrels, knuckleheads backing up on blind corners...

craig bush · Jul 20, 2023

My understanding of the point folks are making is: raising ride height and raising the pivot are fundamentally different changes, and raising ride height does not move a fixed pivot point relative to the center of mass.

They might have some overlapping effects, but one is not intended to be a substitute for the other (i.e. on a bike with a non-adjustable pivot, raising ride height is not an identical substitute). There’s a reason race bikes have both options.

SuperDomestique · Jul 20, 2023

baggerman said:
Anti-squat is a function of swingarm angle. Moving the rear axle down relative to the swingarm pivot increases anti-squat so raising the rear increases anti-squat just as moving the swingarm pivot up increases anti-squat. I'm raising the forks to shorten the trail. So my changes increase anti-squat, changes the rake (head moves down about 10 mm rear is up 14 mm so about 1 degree less) and shortens the trail. Ain't my first rodeo. In reality I'm looking for a pattern on the tires. When the rear is fully scrubbed I want to see about 4 to 5 mm of front chicken strips on the front. Not necessarily the best race set-up but the set-up I want on a street bike because it increases agility. Helps one dodge rocks, gravel, pucked antifreeze, logs, skip squirrels, knuckleheads backing up on blind corners...

Believe what you want but it's incorrect. Changing fork height doesn't change anti-squat. The angle and force of the chain, which is the primary force for anti-squat, is still the same whether you move the forks up or down. Might not be your first rodeo but sounds like you're riding around in the clown car.

Many factors influence anti-squat not just suspension geometry (gearing, sag, electronics, etc).

craig bush · Jul 20, 2023

SuperDomestique said:
Believe what you want but it's incorrect. Changing fork height doesn't change anti-squat. The angle and force of the chain, which is the primary force for anti-squat, is still the same whether you move the forks up or down. Might not be your first rodeo but sounds like you're riding around in the clown car.

Many factors influence anti-squat not just suspension geometry (gearing, sag, electronics, etc).

Might be theoretical, but to my understanding if you drop front height enough to tip the bike forward (raising the rear, extending the rear shock and shortening the wheelbase), swingarm angle would increase and so would anti-squat.

(Edited)

Rear ride height adjustment

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