I've never heard that described in that fashion. Those little plastic bits are there to fill up space, so the same derailleur can be used with either 9 speed or 10 speed chains. For the narrower 10 speed chain, the bits stay in. For the wider 9 speed chain, you pop them out. The thinking is that the shifting would be slow and sloppy and it would be easier to drop the chain if the derailleur was too wide. Rather than make the derailleur in two different widths, they compromised by just using an adapter.wasfast said:I have a 2004 Record front derailleur on my dry bike and a 2001 Daytona on my rain bike. Is there some guideline as to when to change the wear pad in the cage?