NO you cannot the fork will not allow it or the seat stay on the frame do not have the mounts for the calliper - they arent there! New wheels would be needed even if you could on the frame , estimated cost (with Tektro aguria comp disc & wheels $400 +/-). Sorry but you cant on this model and I sell the GT brand bike too so I know. If you had this one: http://www.performancebike.com/bikes/Product_10052_10551_1074166_-1_51000_20000_51506 you wouldnt have to worry about it.