Understanding Bicycle Gears
Bicycle gears are all about optimising pedalling difficulty to increase cycling speed. You need a low gear to cycle uphill and a high gear to cycle downhill. You should know the gears have changed when you see the gear numbers move up or down on the handlebars. On most bikes, the chain will move up to a smaller cog when you shift the lever to a higher gear. This increases chain tension and makes pedalling harder but more powerful. The time to change gear is when pedalling becomes too difficult or you’re pedalling hard without moving very fast.
Types of Gear System
- Fixed – A bike with one gear is a single-speed fixed gear system where the pedals automatically rotate when the bike is moving.
- Derailleur – Most common gear system where the chain is derailed onto another cog.
- Hub – Gears are changed in an internal hub. Shimano and Sturmery-Archer internal gears are referred to as numeric ‘speeds’.
Number of Gears
Bicycle gears can vary from one or three gears for traditional leisure bikes to 18, 21, 24 or 27 gears – usually found on mountain bikes, hybrids and road bikes. To work out the number of gears on your hub gear bicycle, multiply the number on the shifter dial on the right-hand side of the handlebar with the number on the shifter on the left. It’s easiest to think of hub gears as ‘cogs’ in the front and back mechanisms. The back wheel will have a cassette which the chain rests on. The number of cogs on the cassette amounts to the number of gears on the right shifter. The front mechanism which rotates when you cycle has up to three large cogs.
The number of front gears is shown on the left shifter. Faster bikes will have more gears, e.g. a 27-speed Specialized road bike. Slower bikes will have less, e.g. an old-fashioned 3-gear leisure bicycle.
Try not to bend the chain as it will eventually break. Matching the gear on the left with the gear on the right to keep the chain straight is the best way to go. The chain will be all the way on the left on both cogs in the lowest gear. In the very highest gear, the chain will be all the way on the right. This is okay, but don’t use the left-most ring in the front and the right-most ring in the back or vice versa. Doing so will make it move in a diagonal direction, which stretches the chain and wears it out.
Instead consider alternating which gear set you change. For example, move the right shifter up no more than three gears before upshifting to gear number two. Also, remember to shift up or down while pedalling to prevent the chain from falling off.