Many different means of evaluating a bike make purchasing a new one difficult. Finding their next bike is hard for even those folks who are paid to ride. Because there are so many choices, it is hard to buy a new bike. You need to think about safety, comfort, what the bike will be used for, how often the bicycle will be used, where the bicycle will be used and, if we’re being honest: style. Trying to keep yourself informed of all the new choices, as well those just about to be released, can make it really hard to finally choose the bike for you. Simply apply this test as you go to get your new bike.
The first thing to ensure is you get a bike that is the right size. To accomplish this you need know your inseam measurement. Simply measure the distance from your groin to the bottom of your foot, down the inside of your leg. The goal is to be able to sit on the seat of the bike and still rest your feet flat on the ground. This is for saftey reasons and will allow you to stop the bike if your brakes fail, avoiding any injury.
If you want to ride a road bike, you will need to subtract about nine inches from your inseam measurement. The size of the tires a road bike uses are the reason for this. Designed for cycling around the city road bike tires are thin. With a mountain bike you will need to take away around one foot from the inseam. This is because the tires of a mountain bike are different than those on a road bike. Mountain bike tires will be thick and designed for mountainous terrain. You can of course use a mountain bike for road cycling but this isn't supposed to be their primary use.
It is important you allow for room between you and the crossbar. When you choose your bike, adjust the seat up a few inches from find out the crossbar and then sit on the bike. You should be able to still rest your feet flat on the floor. Each type of bike requires different clearances. A touring bike for example will require around 1", perhaps slightly more. However for a mountain bike you will need 3" between the crossbar and yourself. You need to consider several things when choosing your bicycle for the first time. Do you want to ride your bicycle every day or do you see yourself only riding it once in a while? Which height is most comfortable for you? Would you rather be able to put your feet flat on the ground or would you rather have that few inches between your feet and the ground when you are sitting down? All of these factors will come into play as you make your choice.