Without hills the only way is to ride in a suburban or rural area. You can do 25-30mph safely for miles between lights there which, should be hard enough for mo

Without hills the only way is to ride in a suburban or rural area. You can do 25-30mph safely for miles between lights there which, should be hard enough for most people. Big cities are fundamentally not safe serious athletic cycling, anaerobic or otherwise. At best you spike your heartrate sprinting between lights then stress your body with high HR waiting at a light. Or guys will do near 30mph in a paceline around Central Park and act offended when some tourist steps out in front of them.