2.10.2009

Using the Chainrings

Introduction
The chainring refers to the front gears on your bike. It is the large forward ring on a bicycle that a chain attaches to, in order to transfer energy to a wheel. A bicycle chainring consists of one or more sprockets (a tooth of a gear) that are driven by the cranks (arm attached at a right angle used to impart a circular motion to a wheel) and pedals of the bicycle. See the diagram below for more information on the parts of a bicycle.
When to Use
If you have reached the end of your gears (already on the largest gear in the back when climbing, or the smallest when descending a hill) then it is time to switch to the front gears. Sometimes, when you will be riding into the wind for an extended period or climbing for a long time, you can shift to an easier front gear ahead of time and then use the back gear shift for adjustments. In other words, you can use the front shifter as sort of a "range" selector, depending on general conditions, and the rear shifter for fine-tuning.

How to Use
You move the left shift lever to switch to the next front gear. These front gears are called chainrings. Shifting the front gears often requires the opposite movement of the lever that you would use when shifting the rear gears. Also different is the fact that the large rear gear makes it easier to pedal, but the large front gear makes it harder to pedal. This inconsistency is quite simply due to the laws of physics and mechanical advantage.

Potential Problems
Shifting chainrings is much more finicky than switching the rear gears. You will occasionally have to do some fiddling after the shift occurs to get it to run smoothly. This is called cleaning your shift and it can help prevent undue wear on your chain and derailleur (gear-change mechanism). Speaking of wear, a situation you will want to avoid is one known as cross-chaining. This occurs when you are using big-big or small-small gear combinations as it causes excessive gear and chain wear. When you use the big chainring in front and the biggest cog in the rear, your chain has to run a slightly diagonal course. The same is true when using the small chainring and the smallest cog. Occasional cross-chaining is okay, but be cautious.

Sources
Bicycling Life: How to Shift a Bike
http://www.bicyclinglife.com/HowTo/ShiftABike.htm
Bicycling for Beginners: Parts of a Bike
http://www.bicyclingforbeginners.org.uk/diagram.htm

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