Google Navigation, screen doesn't rotate when in walking mode?

I'm having a problem using Google Navigation. I select a destination, click the "walking button" and rotate my phone, yet the display remains portrait. If I select "by car" - then it rotates as it should. I'm using the phone mainly as a cycle GPS, and my bike mount is fixed to landscape orientation. So is there anything I can do about this? If there is no way to "edit a config file?", if not, is there a way to force the app (using a widget) maybe to rotate? Thanks in advance.