This is not regarding the bike size, but more about spots where you can get a little bit of hill training. San Antonio Cycle in East Pasco County has good maps of roads with hills you can ride in East Pasco County. The Suncoast Parkway north of State Road 50 in Brooksville/Spring Hill area has some nice hills (south of that is very flat), and if you ever drive over to Clermont, there are some nice hilly roads and Lake Mineola trail is pretty hilly - not like mountainous places, but pretty good for Florida.