Folding bicycles by Dahon, Montague and others folding recumbant bikes can be brought onto public transit. They typically cost about $300 to $900. There are several folding bike buyers guides
For a more comfortable ride, get an electic folding bicycle. The bionx can be used to convert regular bikes to electric bikes
If you currently do not use public transit because of delays with transfers and less freedom of movement at your destination then get a folding bike or electric folding bike. The ones with 20 inch wheels or smaller can also be packed on trips to other countries.