The departure of Casey Stoner from Ducati has become a problem for the Italian manufacturer in MotoGP.  Casey Stoner was able to extract from the Ducati, when either sported a trellis frame or a carbon fibre chassis, what no other riders could.  The worth of Casey Stoner as a rider is now obvious with his replacement Valentino Rossi not being able to get to grips with the carbon fibre chassis that uses the engine as a stressed member and the front end and rear end are bolted on to the engine.  The lack of success with Rossi is now forcing Ducati to attempt what it is very unfamiliar with, building a motorcycle around an aluminium twin spar frame.  MotoGP motorcycles in order to be good handlers require a bit of flex built in to them so that the rider gets feedback from the motorcycle and rides it at its limit.  The trellis frame, which is a series of small vertical pieces welded in between horizontal pipes at different angles is an imprecise way of building in flex and that is what led Ducati to go for the carbon fibre chassis that uses the engine as a stressed member.  Now with that no working for Rossi or Nicky Hayden Ducati is taking up a parallel project of building an aluminium frame.  The problem is that this is uncharted territory for Ducati. It is therefore outsourcing the building of the frame to a supplier who is familiar with it.  So Ducati will do both, aluminium twin spar frame and the carbon fibre chassis and will ultimately race whichever is better.