front end "issues"

[TAftonomos]

My freshly modded S4rt rips.  However, it's doing something that startles the crap outta me.

When I'm hard on the gas, maybe 2nd or 3rd, the front end is wobbling BAD.  It's not tank slapper bad (or maybe it is...never had one).  It just feels like it's skimming the ground barely if at all, and each time it touches some pavement it translates into a steering input.  The front is so friggin light, perhaps it's my inputs (involuntary) or the setup is wrong.

Not sure where to start, but it has stock offset triples, Ohlins R&T forks, Ohlins rear shock, BST's, Ti axle. 

Seems really weird leaned over as well.  Maybe it's just the BST's I'm getting used to, but it feels like there is no weight on the front end at all.

[ducpainter]

If you have stock bars there isn't much weight on it.

Chances are it is your input and not the bike.

Why do you suppose people put clip-ons on monsters?

[koko64]

Gday T A

That bike looks awesome and sounds like it is an awesome performer!
Glad you're finally on the road. I have been watching with interest (and envy)!

Do the bars oscilate a little, slowly (wiggle) or towards full lock quickly (tank slap)?

Accelerating over bumps with a light, high powered, high torque bike like yours will give a race track like wiggle in the bars while the front end "surfs" and "ski boats" the bumps. If the oscilations are at a slow rate and not using much of the steering lock then that can be part of a racers feel, lap after lap when you are really "on it". If they use up the steering lock, oscilate rapidly and shake the whole bike in a way that feels like a lack of control is iminent then you want deal with that, because that's the dreaded tank slap.

Such a reduction in unsprung weight/rotating mass will definitely require a change in your settings, so there is a technical aspect to this. As you know that Ti axle and carbon wheels means that the mass and how it behaves in reaction to the road (and you), has changed substantially so you will now have to have a good tuning session on your favorite bumpy test road to dial it in. But that's why you got those parts. Your suspension guy may offer a baseline just to be safe as you have 50hp more than my desmodue.

The other side of things is to try to find anchor points other than the handlebars so you can relax your grip on them a bit like clasping the tank with your thighs and knees or even elbows. While cornering get that inner elbow locked down (especially the throttle side). My apologies, you know all this I bet. It's just sounds your bike has upped the ante on you!
I found the same thing racing going from a '95 ZX6R to a 95 YZF 750. That 750 tried to kill me! Everything about the bike suddenly happened quicker requiring incontinence pad sponsorship..

The suspension folk on the Forum should soon chime so we can take notes.

[koko64]

If you have stock bars there isn't much weight on it.

Chances are it is your input and not the bike.

Why do you suppose people put clip-ons on monsters?

True, a naked bike with handlebars and SBK power will do that. I reduced tankslappers by cutting an inch off each end of my stock bars (and using "shagging the tank" style).

[TAftonomos]

I appreciate the tips fellas.  It's not a lock to lock motion at all, just a wiggle back and forth that isn't confidence inspiring at all.   I can't remember it doing this before the BST's and suspension change, so I am wondering maybe if I've got the geometry all messed up somehow.

I'll double check the baselines again, and try and relax a bit more on the bars.  They are flipped, but certainly aren't clip-ons. 

[swampduc]

Have you considered a steering damper? I know they shouldn't be used to cover up problems, but you've got a motor that's way too powerful for the chassis, especially with BSTs. It's always gonna get light on the throttle. I also agree that clip-ons would be wise, but suspect the damper will be needed regardless for a safety margin.

[TAftonomos]

Ohlins sidemount installed, has been.  Turned nearly all the way up too!

Was bad today, but I'm thinking it might be me (all or part).  Under decel - not braking just off throttle - I'm putting weight on the bars, and getting the side/side motion.  As soon as I let go or release any pressure on the bars at all, it goes away.

[ducpainter]

Ohlins sidemount installed, has been.  Turned nearly all the way up too!

Was bad today, but I'm thinking it might be me (all or part).  Under decel - not braking just off throttle - I'm putting weight on the bars, and getting the side/side motion.  As soon as I let go or release any pressure on the bars at all, it goes away.

ding ding ding

[swampduc]

My buddy (local Ducati tech) suggests you check wheel bearings and spacers if it's shaking on decel as well.

[TAftonomos]

ding ding ding

Is it the wheels that are making this THAT much more noticeable?  I surely don't remember feeling this before.

I'll check the bearings and wheel spacer/front axle Swamp, thanks!

[ducpainter]

BST's will magnify everything.

The ding was for your statement about the problem disappearing when you let go.

People have no idea just how much input they use unintentionally.

The more sophisticated the bike the more effect our input has.

[koko64]

Hey TA
Hows it going?
You modify your suspension settings?

[bikepilot]

Really sound pretty normal to me.  A quick bike should go light on the front end at WOT in the lower gears especially --  a bike with a rearward weight bias like the monster especially so. Learn to control your inputs, grip with the legs etc and revel in the exhilaration, riding isn't supposed to be an entirely sterile activity 

[TAftonomos]

I double checked everything that I can think of in the suspenders, and it all checks out.  Sag is setup (25mm front, 30mm rear), pretty sure it's "tuned" correctly.

Nate was right, it's just crap I was doing this whole time that I didn't realize.  Pounded on it pretty good today on the way to work, the more I ride it the better I'm getting at minimizing what I was doing and feeling what the front end is doing.

Now...if I could just figure out how to get it to do what I want, or at least interpret how to correct when it does something I don't like/feels wrong.

I suppose I need to take a class or 3

[stopintime]

Same thing happened to me post BST-mod.

I raised the front by 4 mm and the 'wobbling' was gone.

It's still very sensitive to inputs, but that's fine - just need to pay more attention.


http://www.ducatimonsterforum.org/index.php?topic=50563.0