Originally Posted by
dsbrantjr
Identify the crankset you intend to install and buy the BB length specified for that crankset.
It has nothing to do with the chainline? Or is it a mix of crankset position (therefore chainring position) + spindle length gives a particular chain line?
Originally Posted by
jimc101
Id the crank, then look up the manufactures specification?
For the 1.37 x 24t, that's the thread spec, but in bike terms, it known as an English thread, You won't hear it talked about in day to day usage as a 1.37 x24t unless you frame building/designing/manufacturing BB's.
The simplest thing if looking at the crank is to get an external cup BB (i.e. HT2, MegaExo or GXP), then you don't even need to think about the spindle length, as it's fixed.
I don't want to do the simplest thing, I want to learn how to do the thing right
Besides, I've already had the internal vs. external debate, I'm going internal BB, most likely a simple, cheap shimano UN-55.
So if I look up the nexus, it specifies a "chainline" of 42. I'm assuming that's 42 mm, so that means I need to find a crankset + BB length that puts the chainring 42mm from the center of the BB... right? Or am I way off base here?