Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > fitting Mag wheels - suspension adjustment?

[Bungi]

Iam pretty happy with the way my suspension is currnetly set up, and i am by no means an expert on suspension,

however if i am to fit my marchesini mags will i need to make any adjustments to the damping or such like to reatin the same feel and perfomance from my bikes suspension,

i am a bit nervous about making changes that in turn require other changes to be made however the mags are bound to offer some overall benefit, I just want to be sure i dont run into any trouble on the road or track and end up in a heap.

seems logical that the damping might need to be backed off, is this the case?

seems many of you have used mags and possible interchanged them with standard rims for trackdays ect, how have you managed with any suspension changes that have been necessary as a result.

my bike is a 996r witch has ohlins front and rear, and I ride it as hard as I can on trackdays so as i said I dont want to end up in a heap.

[skidlids]

As Shazaam has pointed out in a previous post some tyre weights differ a fair bit and nobody appears to worry about its effect on suspension.
And I previously posted about the fitting of lighter springs and reduced damping when fitting lighter wheels, which when you are racing at BSB level or above will probably make a difference, just check out how many rear shock springs a top team takes to different race tracks. If you can really notice the effect on your suspension from the lighter wheels then be prepared to do a lot of testing to find the best set up and then you will be doing the same everytime you get to the each different track. Best bet is to settle for a compromise and just dial in what you all ready have to the best setting you can get.

[Shazaam!]

To add to skidlids post:

When you replace the OEM wheels with lighter magnesium wheels you need decrease rebound damping, and (to much lower degree) compression damping. A lighter wheel has less mass so it can move up and down faster (the system has a higher natural frequency), allowing it to track bumps that a heavier wheel cannot.

These illustrations will help you to understand how damping affects suspension movement after you hit a bump.




When the suspension doesn’t have enough damping, the bike feels unsettled because it takes a number of bounces (oscillations) before the suspension settles back down (reaches equilibrium) after hitting a bump.




When the suspension has too much damping, the bike feels stiff and unyielding because it takes a long time before the suspension recovers from hitting a bump. If you hit a second bump before recovering from a first, the suspension “packs-up” and transmits higher impact forces to the bike and rider, and the wheel has more difficulty tracking pavement irregularities.




This is what you want. A critically-damped suspension system approaches equilibrium as fast as possible without any oscillation, and in the shortest time, after hitting a bump. This is best because it give a rapid recovery without producing either a harsh or bouncy ride, and will gives the best wheel tracking of uneven road surfaces so as to maximize the time in contact with the road. This maximizes tire grip in corners.

[skidlids]

Don't I wish i had a physics teacher like Shazaam when I was at school, would have got me upto speed on these things a lot sooner.

[Bungi]

this firstly very usefull and seecondly reasssuring that i was thinking along the right lines,

does anyone specifically have a pre developed rule that works sucah as one click off on the rebound etc. or does this even more complexly depend on how much you weigh.


Im not in the habbit of making adjustments for differant tracks although I can understand at race level this applies, I guess I was just hoping for a simple answer to a more complex question.

look like il have to start from where i am with the std rims and tinker till it feels right.

thanks

Bungi,

Why not get it set up properly, you should get in touch with HM Racing in Orpington, Kent, they offer a full setup service and you wont be disappointed.

I had mine done and it was probably the best "value for money" work I invested in ...

www.hmracing.co.uk

Ask for Perry Leask ....

Good luck mate ....

[RickyX]

In theory, the damping curves that Shazaam has posted are fine...however they only relate to the damping response from one input - i.e. a certain size of deflection at a certain speed.
The ideal solution is variable damping that can recognise the size and speed of the input and react to that with the critical damping value. This of course costs loads and is therefore not practical.

Bungi - I have mag Marchesini's on my 748 and have set it up to suit me (10-11st, solo only, CF bodywork wet weight 199kg). If you want my settings I can provide them.