"...Based on this, I would like to ask the readers out there who live in large metropolitan areas or have to ride in less than safe areas, how they go about protecting themselves. What is your plan if something happened?

Do you carry pepper spray?
A firearm?
Are you trained in martial arts?
Do you think you could just out ride someone chasing you?"

I ride in a busy metro area, daily, all year. I have never felt personally vulnerable and worry more about vehicles and jaywalking peds all the time. I don't have a plan, but carry a cell phone and stay very aware of my surroundings. There's only one part of my commute where less than savoury characters can be encountered, but I'm aware of that and my "escape" routes if anything should happen. Luckily, no part of my commute is without a highly trafficked roadway, pretty much at all hours.

No, I do not carry a weapon of any sort, nor do I have martial arts training. Yes, if that person was on foot I could out race them, and if it's one of the referenced unsavoury characters, yes, I can outride them too. I've seen the bikes they use and the poor physical shape they are in. I am not concerned about fellow bike commuters.

I have female and male friends who could easily bike to work if they wanted to (they have good bikes and are physically active). Their #1 reason for not doing so is safety. #2 is pure laziness. And they will admit this.