First of all, I am insanely happy that Google has added bicycling directions to Google Maps. As someone whose bike is their primary mode on transportation anywhere, this will instantly become a regular part of my life.
Upon trying it out, I tested my work commute. The results were almost exactly spot on, which is impressive considering they have not had any time to fine tune things (which they say they will do if you write suggestions using the “report a problem” button in the bottom-right corner). There is no key, but anyone who has looked at a bike map before will instantly recognize the markings (dark line means dedicated bike path, lighter solid line means bike lane, dotted line means either sharrows or a common bike route).
Another thing that is amazing is that you can overlay the bike map on the terrain map. So now you can zoom in to get more up-close geographic data for that one spot where you are worried you might hit a hill…
I did notice one area where the map should be changed (I’m sure things like these will come up a lot, as there are a LOT of little details a computer giant could not know without being on the ground riding). The directions suggest riding down Westlake on my commute to work. While I am fine riding on Westlake, I feel like it can be scary and dangerous for a new rider who is not prepared for the trolley tracks on the road south of Denny Way. I wonder what their strategy will be when it comes to streets that are slightly dangerous, such as this one. Should all streets with trolleys but no bike lanes be taken out of the street suggestions?