the new bikes have 2 different 3 speed hubs, BSR is the continuation of the AW3 lineage.

BWR is a wider difference, between the gears, but the 2 cogs, 13/15t
are half step apart, and so the spacing between gear combinations, is tightened up .

the 2 speed is the 2 cog external gear shifter, and a 12/16t combination..

off the shelf, crank gear choices: 44, 50 and 54t
but there is no issue replacing the single ring crankset, with 2 chainring cranks.
you can kick the chain to downshift, just stop and use the greasy finger shifter
to go back to big ring..

I had a friend interested in my black M bar AW3 speed with a rear-rack, [50/13]
but they backed out .. so talk to me off list.. PM