I apologize if this topic has been dealt with previously. I'm converting a spindle/ballbearing BB to a Shimano cartridge BB (think: UN54 etc). The bike (Miyata 916 steel frame) has a plastic cable guide below the BB housing. The guide is mounted with a screw that protrudes into the BB. This interferes with the cartridge BB.
On my daughter's Specialized Sirrus (also steel), I have actually shaved down the length of that screw. But I am wondering if there is a better way e.g. a cartridge BB that has a narrow diameter than the Shimano series of square taper BBs.