I am getting a Shimano 105 crank, and don't know what size bottom bracket to get for it. It is an english thread, but they come in 110 113?
There have been several generations of 105 cranksets over the years. If your crankset is a modern 5600 or 5700 series, then the bottom bracket spindle is integrated into the right crank arm. You don't choose a spindle width. The bottom bracket consists of two bearing cups through which the spindle is inserted. The 5500 series uses an octalink bottom bracket. You choose either the 109mm for a double crank or the 118 for a triple. The early 7/8 speed 105 cranks (1055/1056/1057) used square taper spindles. On these, you choose the width that gives you a good chainline. For a road bike with a double crank and 43.5 chainline, you'd probably choose a 113mm (1055) or 107/110 (1056). For a triple (1057) with a 45mm chainline, you'd probably need a 118mm spindle.
