Using a measuring tape, measure the distance from the top of the seat tube to the middle of the bottom bracket (A).
For a road bike, you will need to list the size in centimeters. To convert inches to centimeters, simply multiply by 2.54
For a mountain bike, list the size in inches.
If you want to get really technical, measure the top tube ("B") and include that information in the item description along with other sizing information
Now that you have the bike size, find the type and size of bike you are selling, select the information, copy, and paste into your listing!
Click here for Road Bikes & Triathlon Bikes
Click here for Mountain Bikes & Hybrids