Originally Posted by mswantak
As though the wheel is going to end up going anywhere else except between the pads. For all the practical benefit they provide, I'm more inclined to think they were primarily a snob appeal gimmick -- the bicycle equivalent of curb feelers.
Ever tried a fast wheel swap without guides? You usually slam the wheel right into one of the brake pads.
Happens nearly every time if you're trying to change the wheel in a hurry - Murphey's law! Using guides helps to slide that sucker in correctly most every time.
Take care,
-Kurt