Cannondale had a geeat post with pictures and all on last year or the year before. Essentially you need to remove the airbox and it is right there. Use a set of Channel Locks to get it loose, watch out for the oil pressure sending unit. I unplug it. Use a K&N replacement filter, they have a nut welded onto the end of the filter, makes it a ton easier the next time. After you change the oil once it is not that hard. Search this site for that post of Cannondales, it is really good.
