My road bike is a Giant OCR1 and it's great!
But for the bike paths I ride my brother's old basic Marin mountain bike - actually I think what makes it so hard to pull is that I don't have clipless pedals on the mtn bike so I'm not getting the whole pedal stroke. I may just break down and just get the SPD pedals.

Either that or I need to move to a less hilly area My town is the "Gateway to the Poconos" so everything is pretty much hilly around here and it kicks my butt!