About this 3D model

This tool can be used to loosen that Torx-like cap, which is holding the left crankarm on the bottom bracket spindle (see picture). This is needed to swap/clean your crankset or replace the chainrings. The video here explains how to remove your crankset http://www.youtube.com/watch?v=hs_ywOIYzdY There are plenty of instructions about this procedure online. Don't be worried about this tool being made out of plastic - the original is as well.