Most likely, that means you are only putting a 12:1 reduction on the CIM motor... which depending on what size wheels you are using could be a bit fast. Do the the calculations with the motor specs from
here and figure out how fast you will be running. Then we can give you a good idea if its too fast, usually a fast FIRST bot is 10 ft/, and a slow bot would be 3-4 ft/s. All depends on how you are playing the game.
edit: I would worry about putting that much load on the shafts of the gearbox's, i would highly recommend putting the bearing blocks on the other end of the shafts if you are direct driving it.