Originally Posted by Paul_P

Thanks for the clarifications. This is for a 3x8 MTB (2005 Specialized Hard Rock Sport). Right after writing my post, I realized that everything probably revolves around the chainline, so should that be chosen first then everything else ? Above Shimano specs are for 50mm.

The current BB is a TruVativ with a 113mm spindle according to the above specs (68mm shell). I don't know that the current chainline is, and I guess I have to figure out what I want it to be ? Like which gear combination is the most used and then chose the rest so the chain is the straightest for that combination ? Current Q-factor seems to be about 180mm and I'm pretty sure I'd be more comfortable with a bit more.