My hybrid (Gaint Roam 2) is currently fitted w/ the stock low-end Shimano FC-M371 3x9-speed crankset...which has riveted gears.

I'd like to swap out to something w/ replaceable chainrings, but I can't seem to find much definitive information on an easy swap. It would be nice to reuse everything else...

Assuming that modern Shimano square taper cranks all fit the same JIS pattern....how do I find the proper "offset" to keep the chainrings in the same relative lateral place?

Do I have to swap out the BB too....or is there a direct replacement that will work with the current BB/FD/etc?

I'm capable of doing the wrenching & small adjustment tweaks to the FD if needed, but yeesh are there a LOT of options out there!

Thanks for any help!