I recently published a post addressing different cranksets and the need to match your range of gearing with both your skill level and the terrain you are riding. This video by Georgena Terry is the best explanation of bicycle gearing I have seen.
Georgena Terry is a steel frame builder perhaps best known for making smaller frames for women cyclists. She builds exquisite bikes but her real strength, at least in my mind, is her innate ability to visually explain complex design concepts. Frame geometry. Wheel sizing. Bicycle fit. Gearing. Lugged vs TIG-ed frames. Bicycle maintenance. She has produced a series of videos I would recommend cyclists of all levels watch. The “Tech Talk” tab on her website (www.georgenaterry.com) also contains a lot of very useful information.
Become acquainted with Georgena. You will gain a better appreciation for bike design, how to fit & maintain your bike and, how to purchase your next bike.