Are they a standard sort of size or are there dozens of variations?
they’re bearings on a bicycle which approach do you think the industry has adopted;
a) standardised across all models and manufacturers to make life easier for retailers and end users
or
b) invented multiple standards, adopted them inconsistently even in seemingly similar models from the same manufacturers and superseded some of them even before the end of a model year.
🙂
this is the current FSA choice I think;
edit 2:
loads of useful info here:
http://dansbikestuff.blogspot.co.uk/2013/11/headsets-and-associated-standards.html