A brief history lesson for you groms:
# 366 Safety Bicycles and Bicycle Gears
Penny Farthings were the oldest type of bicycles that were made. They had only one big wheel and were quite tall where the person cycling could not balance himself by his feet. The next generation of bicycles were the Safety Bicycles which had two wheels and were created using a diamond pattern. They were introduced by Harry John Lawson in the year 1876. They were created considering the safety features like the rider could balance himself well with his feet since the cycle was such that his feet could reach the ground. The pedals that were created moved the rear wheel and worked through a chain drive system where the pedals moved the chain and the chain helped in moving the wheel. The revolutions of the pedal in safety bicycles were more than the revolutions done by Penny Farthing and therefore the rider covered more distance with less energy for pedaling. The safety bicycles were women friendly as well because of its height.
The gear part of the cycle was added as a plus point where riders moving over high mountains could easily move without applying too much of pressure on the pedals making the riding comfortable. Similarly they made it easier to ride down the slopes and in greater and controlled speed. Pedaling slower or higher than your pedaling speed (cadence) would be a waste of energy. There is a risk of injuries on your thigh muscles, joints, hips or knees. Therefore having many gears on the bicycle made it possible for the rider to find his perfect cadence which would not require too much energy or strain on the legs.
Bicycle gears can be calculated on the basis of distance in meters covered by the bicycle for every turn in the pedal. There are high gears and low gears in the bicycle. High gears allow the rider to easily move with higher speed and vice versa. Shifting of the gears is done through the handle bars. Going to a lower gear is called as Down-Shifting while going to an Upper gear is called as Up-Shifting. There are rings that are attached to the chain on the center of the wheel on the bicycle and more the number of rings means more are the gears. As the rider selects the lowest gear the chain moving through the pedal shifts itself to the smallest ring, which is on the outer side of the wheel and similarly when the rider selects the highest gear the chain moves to the largest ring which is located at the inner most part of the wheel.
High gear bicycles are much in vogue and are purchased by people who have a love for adventure cycling. Companies are introducing their new bicycles calling them as multiple gears or infinite gears. It is generally a marketing hype created in order to increase sales. The gear feature obviously contributed to increase in the sales making a simple bicycle known as mountain bike. There are sales specialists who have knowledge in sizing and they can look at your body structure and decide what type of bike is perfect for you. Also companies provide test drives to their customers so that they can decide on the type of bicycle they want on the basis of its gears. Thus safety bicycles created a surge in the development of gears in bicycles and major changes in the gear shift pattern were brought along by the safety bicycles.