awgee, it really depends where you ride, if you find a nice flat trail or paved trail it's relatively safe, I don't think any kind of cycling is 100% safe but neither is driving a Car. You should always wear a Helmet, broken arms and legs can be fixed, heads can't. Road Biking is all about endurance, mountain biking is more about balance and sometimes it's pretty hard to find a good balance on a mountain bike if you're going up or down a steep climb, you have to shift your body weight forward and backwards to either gain traction going up or prevent yourself going over the bars on the way down....if you don't already have a Bike and would like to take up Cycling I'd be more than happy to give you some advice. Any kind of Cycling has it's inherent risks of course but the benefits can far outweigh them....