Enforcement level: Police willingness to cite dangerous behavior by and toward cyclists.
Drivers and pedestrians who don't share well, cyclists who try to run down pedestrians or who weave in traffic, etc., all make cycling harder. How well do the police know and enforce local ordinances?
This would be a good modifier to have although it could be tough. I'm not looking for iron-clad enforcement, especially when I'm on my bike :). However, I'd like to know that reasonable traffic enforcement efforts are in place that are evenly applied. Drivers & cyclists both always have room for improvement.
Additionally it would be good to collect, collate, and send reports to local law enforcement as well as news agencies