Not quite clear what you mean here (and this is not (just) being pedantic). I assume you are not talking about brakes (eg on some TT frames) designed to operate behind the forks. If you fitted the front brake behind the fork crown on a normally proportioned bike, it would foul the down tube. Or are you saying that front brakes are sometimes fitted on the rear (with a longer mounting bolt).Front brakes are not always fitted on the front.
It's a dodge I've used on older frames to avoid having to drill a thin brake bridge out to accept the sleeve nut. The longer bolt of a front caliper means you can just use a normal (nylock) nut to fit them.Not quite clear what you mean here (and this is not (just) being pedantic). I assume you are not talking about brakes (eg on some TT frames) designed to operate behind the forks. If you fitted the front brake behind the fork crown on a normally proportioned bike, it would foul the down tube. Or are you saying that front brakes are sometimes fitted on the rear (with a longer mounting bolt).