A road bike will get you to the triathlon finish line just fine. It may not be as quick, but it is also not as sluggish. In reality, with proper training and coaching, you can be quite competitive on a road bike. Road bikes are commonly used by individuals who want to avoid the overhead costs of racing while still being able to compete successfully against more experienced riders. They are also popular with individuals who want to race but cannot physically handle the stress of a full-on sprint. Many triathletes choose to use a road bike because they believe it is more "fair" than a mountain bike or cyclocross bike. This is not true; any type of bicycle can be fair game if you know how to ride it properly. But yes, a road bike is much easier to control than a mountain bike, so it does give you an advantage if you have never ridden one before. And since it is on flat roads most of the time, it also gives you an edge over people who may be riding mountain bikes. There are several factors that go into choosing what type of bike to use during your triathlon. First and foremost, you need to determine how much experience you have. A novice rider should probably stick with something simpler to manage, such as a road bike, whereas an experienced rider could probably handle anything that doesn't require full-on sprinting at the end of the race.