Square taper to hollowtech. I am going to switch to hollowtech and im not sure how to get the size of the bottom bracket I used to have a 120mm square taper
HOW TO: Square Taper to Hollowtech II Conversion // Bottom Bracket & Crankset - YouTube
The complete guide to bottom bracket standards - BikeRadar
Replacing Square Taper Bottom Bracket To Hollowtech II - YouTube