Whether you're a weekend warrior or a top-notch criterium racer, shifting your gears efficiently can make a world of difference in your performance on the bike. A smart shift can make the difference between winning the sprint or ending up at the back of the peloton. Learning the basics will help you to make fast, clean shifts while maintaining higher power throughout your pedal stroke.
To become better at shifting, we must first discuss cadence. Cadence is the rate at which you turn the cranks of your pedals and is measured in "rpms," or rotations per minute. Research shows that on average, the human body performs best in competition with a cadence of around 90 rpm. Without the benefit of an in-depth study on your personal cadence, we will assume this average works for most people.
Gears and Cadence
The gears on your bike are the mechanisms that transfer pedaling power to the rear wheel while maintaining an efficient cadence. To increase cadence (because our rpms are too low), we may need to "shift down" to find an easier gear. If we find ourselves spinning our feet too fast, we may "shift up" to find a harder gear.
Lower gears (the ones with more teeth on the cassette) are used at lower speeds and for hard climbing. Higher gears (cyclists generally say 'bigger gears') are for higher speeds and sprints.
Efficient shifting requires the proper use of your front chainrings. Let's assume your bike is equipped with a double crank, or two chain rings up front. The small chain ring is usually used for climbing at speeds under 15 mph while the large chain ring is used at higher speeds on flats or rolling terrain.
More: Bike Shifting 101
A common mistake made by beginners is to use the small chainring up front and the smallest cogs of the cassette in the back. This is commonly referred to as "cross-chaining" and may have a negative impact on your shifting. While it might be convenient in some situations, it decreases your drivetrain efficiency. The diagonal travel of the chain increases friction and adds wear on your chain rings and rear cassette.
When to Shift
The goal is to make the timing of your shifts natural so that it's easy to maintain a consistent cadence. Waiting too long to shift down on a climb could leave you at the rear of the pack with a grating, skipping chain as you struggle to find a smaller gear. To avoid late shifts, plan your shift ahead of time. Scan the route in front of you. Is there a sharp curve or hill ahead? Try to tackle short hills without any change in gearing. Longer hills will require a down shift in order to efficiently transition to climbing mode. Sharp turns require braking and acceleration from a lower gear.