Which disc brakes for my cannondale super-v?

pjwapchimp

Hi all. Ive got a 1998 cannondale super-v. Its old but spotless as it was well looked after. I have 1999 marzocchi junior-t up front. Both the fork and rear swing arm have the same disc mounts. Im not to sure whats the best, cheap disc brake setup to get. I always intended to fit discs but they were way to expensive when I built up my bike. I have found some shimano discs on ebay and mount adaptors. Any help on what size disc etc I need to get and what type of mounts I have, would be appreciated. Cheers.