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Discussion Starter #1
Anyone catch the race in Thailand? Seems like he was dealing with some serious wobble... even my wife noticed it after stopping to look at the tv for five seconds. I know the 1199/1299 family has supposedly had issues with high speed wobbles, but thought they would have sorted out at this level (the other ducs seemed to have figured it out).

Wobble Wobble
 

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Yes! I saw it! Crazy, he was able to continue the race.
 

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Saw on another forum that it's apparently because of how light he is... which seems a little ridiculous. Its world superbike not some guy riding around on a stock bike that was designed with the "average" rider in mind.
 

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Bon Vivant
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My guess: most racers will tweak the geometry to the point of instability in favor of turn-in. In the amateur ranks we most often raised the rear steepening the rake, we would adjust and ride until the bike became wobbly and then backed it down just enough make the bike ride-able. I'm thinking Melandri was trying to eek out that last bit of turn-in and left it a little too unstable. I'm sure the pros do more than raise the rear to affect turn in but no matter how you do it its always a trade off...
 

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Speed wobbles were pretty common when I first started riding bikes. The older bike frames were spindly and under certain conditions (worn tires, underinflation, loose swing arm or steering head bearings) the bike would go into a speed wobble. I actually studied this phenomenon while in college in one of my engineering classes. Speed wobbles happen when an external forces are applied to the bike at a frequency that matches the natural frequency of the bike. Look at it like this; the motorcycle is like a tuning fork. If it is struck with an external force it will vibrate at some natural frequency. A speed wobble (resonance) occurs when the frequency of the external forces gets close to or matches the natural frequency of the bike. The external forces typically come through the tires from undulations in the road. Throttle on or off also effects the resonance. During resonance small inputs of force match the natural frequency and things start vibrating wildly. Its like pushing a kid on a swing. You push at just the right time and you can get the kid to swing really high.

I have encountered these alot on an old Norton I used to race. You can change the natural frequency by changing your position on the bike (move forward or back ward). It also was true that cutting the throttle made it worse. If you are at the pure resonance frequency, the amplitude of the vibration can actually tear the bike apart. You usually crash before that happens.

It is unusual for newer bikes to have these problems. At least for me, most of the Ducs I have ridden, I have never had even the slightest hint of a wobble. I was almost thrown off a Hypermotard once after wheelying over a hill and come down on some rough pavement, but luckily it only wobbled for a short time although quite violently. The one feature that I really liked about Ducatis, is the stability of the bike at high speeds and in turns.

I would think the factory could fix the problem with Melandri's bike. But apparently, this particular bike, with his weight, puts it in a resonance condition.
 

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I watched both races, and those were some major wobbles, and in the middle of straightaways too. this is 2 track (4 races) in a row now that he has struggled with this. Davies and Fores did not seem to have this problem on the same bike. I dont know if its a weight issue, or just how he is loading the bike down the straights and into the braking zones, or how he is using the throttle.
 

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My understanding is that they've added approx. 3" to the swing arm in order to increase stability. May be they need a few more inches :).
 

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Maybe it's on purpose, might want to keep people from getting too close! Like others have said he probably wants quick steering for the tighter stuff.
 

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Odd, we can't figure it out either!
 
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