The Ducati swingarm debate

<div class='quotetop'>QUOTE (#22 @ May 31 2009, 05:50 PM) <{POST_SNAPBACK}><div class='quotemain'>Ok so Casey was using an aluminium swingarm this weekend so why?

I read with previous thread with interest, I have knowledge of vehicle dynamics but not that much to do with bikes so I thought i'd restart this conversation since Casey obviously prefers it if he has switched back. So whats the reason? Is it to do with the Ali one having more flex? Which I presume softens the rear slightly for wet conditions? Also I was thinking of the change in unsprung masses. Beaing that the whole rear of the bike (not counting the tail fairing and exhausts) is an unsprung mass, and the aluminium swingarm is heavier what benefits does this have, and what changes would need to be incorporated into the suspension (I'm thinking spring rates and bump/rebound would be affected)

I'll read the responses with interest...thanks.


In the post race interview thats the answer he gave because of the bumps

<div class='quotetop'>QUOTE (#22 @ Jun 1 2009, 12:50 AM) <{POST_SNAPBACK}><div class='quotemain'>Ok so Casey was using an aluminium swingarm this weekend so why?

I read with previous thread with interest, I have knowledge of vehicle dynamics but not that much to do with bikes so I thought i'd restart this conversation since Casey obviously prefers it if he has switched back. So whats the reason? Is it to do with the Ali one having more flex? Which I presume softens the rear slightly for wet conditions? Also I was thinking of the change in unsprung masses. Beaing that the whole rear of the bike (not counting the tail fairing and exhausts) is an unsprung mass, and the aluminium swingarm is heavier what benefits does this have, and what changes would need to be incorporated into the suspension (I'm thinking spring rates and bump/rebound would be affected)

I'll read the responses with interest...thanks.

When it rains, with a little bit of lucks any one could win the race. It has nothing to do with the swim arm. Had the race with 3 more laps, Lorenzo and Rossi could pass Casey today..

<div class='quotetop'>QUOTE (V5Stroker @ May 31 2009, 06:27 PM) <{POST_SNAPBACK}><div class='quotemain'>When it rains, with a little bit of lucks any one could win the race. It has nothing to do with the swim arm. Had the race with 3 more laps, Lorenzo and Rossi could pass Casey today..
but the swing arm did make a difference. thats why casey ran it instead of the CF one. they will more than likely revert to the CF arm at the catalan gp.

and why did both yamahas work on a race strategy for 26 laps? the race was only 23 laps! big oversight on their part...

I reckon with the weather being unpredictable, he thought it would be better go with what he knows, rather then taking a bit of a chance on some new technology. As his 1st place finish shows he made the right choice.

maybe he has more set up choice with the old tried and tested ally one. this cf one is all new and im sure they will get it working in all conditions. i hope they carry on with this experiment. You got to take your hat off to ducati for trying it.

My guess would be the flexibility issue, maybe the CF extreme rigidity could cause more suspension problems (chattering, tyre degradation even) than the alluminium one.

We'll see what they do next race, Montmeló is a circuit of fast cornering were IMO a rigid set up should be better. If they still use the alluminum I guess it's just the carbon fibre is not working for some reason and the Al is better over all.

Still I think neither today or Le Mans was a good testing environment due to the changing weather conditions.

<div class='quotetop'>QUOTE (Teomolca @ May 31 2009, 08:46 PM) <{POST_SNAPBACK}><div class='quotemain'>My guess would be the flexibility issue, maybe the CF extreme rigidity could cause more suspension problems (chattering, tyre degradation even) than the alluminium one.

We'll see what they do next race, Montmeló is a circuit of fast cornering were IMO a rigid set up should be better. If they still use the alluminum I guess it's just the carbon fibre is not working for some reason and the Al is better over all.

Still I think neither today or Le Mans was a good testing environment due to the changing weather conditions.
looking at the rear end problems with the wheel lifting and chattering on friday may backup your theory.

i wonder if Ducati's longterm knowledge of Bridgestones plays into it too.and a good winter of testing/feedback,
hasn't Canepa done a million miles round mugello.? on the Duc

Anyone know what swingarms the other duc rider were using ??

<div class='quotetop'>QUOTE (V5Stroker @ Jun 1 2009, 03:27 AM) <{POST_SNAPBACK}><div class='quotemain'>Had the race with 3 more laps, Lorenzo and Rossi could pass Casey today..

I'm not so sure.......
I think Lorenzo was done at the end, and Stoner pulled out 3/10ths on the last lap. I think he was just managing the gap while Capa was behind him.
Rossi maybe different story ???
I think Stoner had the potential to be as fast as Rossi / Lorenzo over another 3 - 4 laps.

Lets not forget Casey was rining the last 6 laps wiht a clutch problem. He pumped those lap times out wilist contending wiht

- Initial slippiing clutch and in turn massive power deficit.
- Having to adjust it on the fly whilst riding competitive lap times.
- Then getting power back through the bike and having the rear lock on corner entry...with wet patches on the road.

To me it appeared Casey managed to do that and maintain the gap to p2, i am sure there was more in reserve if needed.

<div class='quotetop'>QUOTE (Nuts @ Jun 1 2009, 12:06 AM) <{POST_SNAPBACK}><div class='quotemain'>I'm not so sure.......
I think Lorenzo was done at the end, and Stoner pulled out 3/10ths on the last lap. I think he was just managing the gap while Capa was behind him.
Rossi maybe different story ???
I think Stoner had the potential to be as fast as Rossi / Lorenzo over another 3 - 4 laps.
If you listened Stoner was just managing the gap. Every time they would say something about Jorge gaining on Casey they would say right away he pulled out more of a gap. I think if anything was going to happen Rossi would have gotten Jorge.

<div class='quotetop'>QUOTE (V5Stroker @ Jun 1 2009, 03:27 AM) <{POST_SNAPBACK}><div class='quotemain'>When it rains, with a little bit of lucks any one could win the race. It has nothing to do with the swim arm. Had the race with 3 more laps, Lorenzo and Rossi could pass Casey today..


Casey pulled out an absolute blinder must have been 2nd last lap, (I'll watch it again tomorrow), I think he just stayed in front and got across the line. Also Casey chose the softer tyre for the reduced number of laps he would have to do on it.

He jumped back on the bike with 2/3 race distance to do and rode to that, he was winning no matter what, his tyres gave him the advantage after the bike change and didn't wear out by the end.

Also - credit for this goes to Roger, we were both posting while watching the race and we discussed it but Roger brought it up.

I also have a theory that Ducati have tried to create a more universal package, swap swingarms, frame tension and try and create a bike for all tracks.

Pity they didn't create a bike for all riders.

The choice of the aluminum swingarm was made earlier, it was not dictated by rain. The interesting bit is that Stoner said they can use either one or the other without changing the setup of the bike... He said aluminum was giving them a bit better traction in some key corners--let us not forget Mugello has very fast corners, it's a peculiar track similar only to Phillip island and (old) Assen. It will be interesting to see what they use in the upcoming races.

Regarding the race, Stoner basically won by lapping much faster than others in the first two laps on slicks--in typical Stoner style, he was fast from the start, no hesitations. Rossi lost for lapping much slower than others in the first two laps with slicks... when he began lapping faster (he even set the best lap of the race if I remember well) it was too late

If the geometry were exactly the same then it would be a material difference. But I can't believe they have the same shape so it must be a combination of things none of which I am lucky enough to know. It may just be down to the fact that they have used the aluminum swinger more so it is fairly predictable. I think Stoner didn't need to take any chances in this race he needed a good consistent bike so they went with what they know. Carbon is the future I think for everyone.