Originally Posted by
BLACK BIKE
This might be of use to you: When I switched to a Dura Ace cog, It threw my chain line off a bit. I had to use bottom bracket spacers to move my bottom bracket out about 1.5 mm. So if you are planning on swapping the stock cog out, I suggest you do it before you buy a bottom bracket; so you can measure the rear chainline and select a bottom bracket accordingly. I have a 2007 Pista.