At the risk of being pedantic, it's British Standard for
Cycles, BSC = 1.370" x 24t
There are a gazillion formats right now, more than ever. The
man who knows which will be dominant in ten years ought to
take up poker or lotto as a career.
That said, they all work[1] and so you have two paths;
choose a model with BSC threads and move your old crank to
it or choose a new frame based on fit, geometry, weight,
price, aesthetic, racing history, recommendations from
friends or 'experts' and/or your personal prejudices[2]
and, if all that leads to a non-BSC frame, then just fit the
matching crank and crank bearing.
[1] Really. If anyone thinks a press-in formats of 46 or
41mm diameter, or 68 versus 86mm width are clearly superior
to the others, I'll listen.
[2] Despite claims of rational winnowing of data, my
experience leads me to believe a lot of new bike selection
is more emotional.
--
Andrew Muzi
<
www.yellowjersey.org/>
Open every day since 1 April, 1971