Mountain Biking - Rules of the Road?

One day my friend and I were leaving from our house to go ride some trails. Luckily the mouth of the canyon is only 3 miles from my house. So we take residential roads to the mouth of the canyon. What I noticed about my friend that is that she doesn't stop or hardly slow down at stop signs. She just blares though like there wasn't anyone there. When in fact we were facing a car that was wanting to turn in front of us. I actually stopped at the sign and the poor driver didn't know what to expect because he had just seen one mountain biker ignore the signs. I was upset; because if I were that driver, I would have flipped off and cussed out the biker. And I'm sure he is going to sum up all mountain bikers into one category now, since he couldn't differentiate between me stopping and her not stopping.

Is this fairly common for people to ignore the rules of the road? I know bikes are vehicles and should obey the rules of the road. However, if I can see in both directions quite clearly and see no cars, yes I admit I may not stop. But when there are cars clearly waiting their turn, what makes her think she's omitted from the laws? I remember her stories of "almost" getting hit, and now I think it must have been her fault!

So how common is this? I did see is alot at college quite a few years ago.
And should I say something to her? Or just wait until we're on the road again and approach a stop sign?

Bikes are vehicles, and we do have to abide by the same laws as drivers do. Some people don't believe in this principal, but it is true.

Advise you friend that she must follow the same traffic laws that cars do or you may not have a friend much longer.

I witnessed this very same incident while I was a passenger in a car being driven to the start point for the Seattle to Portland Ride. My wife was driving and we stopped at an intersection. There were four cyclists in the right lane. There was a car in the oncoming lane waiting at in the protected left turn lane. Our light was red but I did notice that the protected turns were showing green. The car started to make its turn when two of the four cyclists blew right through the intersection. The other two had actually slowed down and waited at the light. The car attempting to make the left turn had to slam on its brakes in the middle of the intersection to avoid hitting the two errant cyclists that ran the red. My wife and I said to the cyclists who stopped, "what's up with your stupid friends?" One of them simply threw up his hands and said, "I don't know but we'll talk to them."