Trek's Madone features a unique bottom bracket (image, right) that's
90mm wide (traditional ones are 68mm wide). This wide bottom bracket
lets Trek build the frame with larger tubes for increased power
transfer. Plus, the 90mm bottom bracket is machined so that the bearings
can be placed directly into the frame (image) saving weight (due to
fewer parts, below), ensuring additional pedaling efficiency and
simplifying maintenance and repair.