yes you can get and adapter to run a 203mm rotor, however many manufactures don't recomend putting a 203 rotor on a qr fork, they will list a max disc size. You still do it, specialized actually has a bike that comes stock with 203s on a qr. Just be aware what ur doing

do you have post mounts or disc tabs?
http://www.ebikestop.com/avid_cps_fr...tor-BR1996.php