Because the seat tube does not meet the BB at a common angle ,
no more than 1 chainring is possible.
...and have a front derailleur to shift gears.
several options : a combination IGH - Cassette rear hub.. 3 by 8..
there are a few internally geared 2, and one 3 speed crank.. still 1 chainring ,
but the gearbox is between the chainring and crank arm ,
so crank can turn at a different rate, than the chainring..
OP is in Florida , a state not known for its hills to climb,
but some hellacious headwinds with named storms..
....
Last edited by fietsbob; 07-26-18 at 11:02 AM.