Google Maps API: How to change Travel Mode at Waypoints

This is concerning the Google Maps API Direction Service, but if it can be done easier in the JS API then that could also work. I was easily able to find out how to change mode of travel and add waypoints to directions requests, but I cannot find an example of a multi-legged journey where the travel mode changes at a waypoint. For example, how do I request directions to the location of a Bike Share rack (where I know the lat, lng) on foot, then to another Bike Share rack by bike, then finally on foot to a final destination from the second Bike Share rack.

Sorry if this is out there already somewhere, my Google-Fu is failing me.