So I picked up an old trek 400 elance cheap off craigslist the same as this model (http://www.vintage-trek.com/TrekBrochure1987.htm#page13). To make a long story short I wont have the bike for another month so I can't measure anything, but I wanted to have some new components ready to put on it when I get it. I bought a new shimano 175 mm 105 FC-5502 crankset compatible with V1 octalink bottom bracket. I will be running a 9 speed setup. I know the old trek has a square tapered bb, so I will have to replace it. I've never replaced a old style bb with the new cartridge style so I'm not sure what size I will need. Has anyone replaced a similar style bb before or have any advice?