Ok, first time post. I am trying to sort out a problem. I want to upgrade to disc in the front. My ride has an older (apparently) Marzocchi Bomber with 9mm drop out slots and IS 51mm caliper mounts... Will I have a compatibility issue if I want to use the Avid BB7’s? Do I simply need to ensure that my new disc hub/wheel has a 9mm axle, or is there more to the story?