Originally Posted by
Wildcat1971
they go between the bearing in the plastic rack. when you assemble the plastic rack onto the plastic cranks, most people back off the screw to prevent binding. With the alum cranks this can make the screws get loose and fall out. So in order to snug the rack onto the alum cranks, a crush tube is used to allow a tighter screw and not bind on the bearings.
corrected
Last edited by Wildcat1971; 05-13-2014 at 11:54 AM.