NEW BB and Cranks
 

Hey,
So i want to switch my bb to a thread style from my current square taper. My square taper is size 68X110.5 , what size of BB do I need for the threaded one? Also, what size crank do i need.

Thanks

You're speaking of apples and oranges. The square taper refers to the end of the spindle (axle) which traditionally was square taper, and can also be a spline fit. (ie octalink).

Threaded would refer to how the BB unit or bearings fit into the frame, of which there are now numerous types.

Oh, so in that case I want to switch my internal bearing to an external bearing. Does that make sense?

shimano makes a couple of nice cranks for road bikes. the Tiagra or 105 models are, IMO, a good value. if you have an english threaded BB, (some info, like bike manufacturer and model, year could help here) the shimano external bearings screw right in and the one piece crank slides right through. the non-drive side crank arm attaches to the spindle with a pinch bolt. if you plan to do it yourself the only special tool you will need, AFIK, is a shimano external cup wrench.

i have a FSA BB-7420ST, 68 x 110.5mm with a Fuji 50/34T Compact crank