Doesn't sound like you know Cambridge at all. There aren't many under capacity roads, especially when winter snow comes down. What this is going to do is make traffic slower, encourage more bikers who will ignore traffic rules and act unpredictably, and generally muck things up. Cambridge is actually probably a really great candidate for bike lanes with multiple colleges nearby, but let's not pretend this isn't going to absolutelymake commuting worse. Biking into work isn't an option for me. When I come into the Cambridge office it's 5 hours in the car round trip. Nevermind the jerk motorcycles who drive down center lanes, cut cars off, pop wheelies in the highway, etc. I can definitely say the animus bicyclists receive is undue. My wife and daughter have been threatened with vehicles, I've been hit in a crosswalk walking by a car, and I can't even get into how bad it is trying to follow the rules in Boston with pedestrians crossing against the signal while you've got a short green.