The worst thing you can do, regarding your safety and comfort, is to buy a bike that is too big or too small.  Nothing can deter you from continuing a riding regimen more than a bike that is unfit for your size.

A small bike will make you feel constricted and hinder a good leg workout.  If the bike is too large, it will throw you off balance and cause injury when you dismount.

Pick a bike size that feels comfortable to you.  Here are a few things to note:

• A bike’s size is generally measured by its frame, specifically the bike’s seat pole tube.  The seat tube is measured from its collar to the chainring hub.
• Mountain bikes and hybrids are measured in inches.
• Road bikes are measured in centimeters.
• Other times bikes are categorized as small, medium, large, and extra large.

To get your correct bike size you must take a measurement of your leg.  Measure the inside of your leg from the crotch to the floor while you are barefoot.

See the chart below for your corresponding frame size.