How to Use Your Gears
If you are puzzled and frustrated by the number of gears on your bicycle, you are not alone. For most riders in our flat Chicago landscape, any number of gears above seven seems completely unnecessary. It is a rare Chicago cyclist who has ever used all the gears on their bike within city limits.
Yet, not everyone wants a cruiser or a single-speed bike. Some folks just want a basic hybrid to ride around town. Until very recently, most such bikes came factory-equipped with more gears than you can count on your fingers and toes, and few salespeople take the time to explain how to use all those gears correctly. Consequently, many riders don't know how to shift gears for maximum benefit, and some new riders are don’t shift gears at all. Many novice riders are afraid that if they shift gears, the chain might fall off. It is worth noting that on a properly assembled bike, the chain should not come off under normal riding conditions. If the chain comes off, it has nothing to do with your shifting, and everything to do with improper gear adjustment, which should be addressed by a bike mechanic.
Shifting systems on most common multi-geared bikes fall into three categories:
Dual derailleur bikes equipped with a front and rear derailleur and two corresponding shifters attached to the handlebars, and sometimes integrated with the brake lever.
Single derailleur bikes equipped with only a rear derailleur and a single shift lever on the right side of the handlebars.
Internally-geared bikes with 3 to 8 gears residing inside the rear hub and operated by a single shift lever on the right side of the handlebars.
Two Derailleur Bikes
Surprisingly, when you purchase a 24- (or 21 or 27)-speed bike, you do not get gears 1 through 24. Instead, you get three sets of eight gears.
Front gears (operated by left-hand shifter)
Rear gears (operated by right-hand shifter)
Here is how it works:
Front Gears: Most bikes have three front chainrings (road bikes generally have only two chainrings) attached to the pedal crank. The small one is easy for climbing; the medium is moderate; and the large one is hard, for riding with wind on your back, or going downhill. These are operated by the front derailleur, which sits just above the chainrings, and is controlled by the left shift-lever on your handlebars.
Rear Gears: For each of the three chainrings (or two, on a road bike), you get eight (or seven, or nine, depending on your bike) gears from the cassette, which is a set of cogs attached to the rear wheel. These are operated by the rear derailleur, which is attached to the bike frame below the cassette, and is controlled by the right shift-lever. Here, the smallest gear is the hardest, and the largest is the easiest. This can be confusing, because it is the opposite of what happens with the front chainrings.
This arrangement of front and rear cogs gives you eight easy, eight moderate and eight hard gears. In a flat city like Chicago, you will probably be using primarily the moderate or high gear range. You will be using your rear gears (right hand lever) more frequently than the front gears (left hand lever). Most of us have a favorite gear or two in which we usually pedal. That's the gear that offers the most efficient cadence when you are moving at a good clip, but not pushing a gear that is too hard, or spinning in a gear that's too easy. And that is the main goal of learning to use your gears.
On a derailleur-equipped bike, you must be pedaling in order for the chain to move to another gear. (If you happen to shift while coasting, nothing bad will happen, but you may be startled when the chain jumps to a different gear as you resume pedaling.) As a rule, shift gears when the riding conditions change, using the gears on the rear of your bike (your right hand):
when changing direction (the wind may now be in your face)
when the road slope changes
when you need to alter your speed
For example, when you pull up to a red light, shift to an easier gear (using your right shifter), so that when the light turns green, you won't have to stand on the pedals to get going. As you begin to accelerate, shift back up to your preferred gear.
You may need to use your front gears (left hand) when road conditions change more dramatically. For instance, when you approach a steep incline, such as climbing an overpass, keep your chain in the moderate gear on the back, and shift to the smaller chainring in front (the left shift-lever). As you scale the hill and the pedaling gets harder, you can gradually drop down to an even easier gear in the rear (using the right hand). Once at the top, shift back to the harder gear in front to get the most out of your descent.
Single derailleur and internally geared bikes
Many new gravel and adventure bikes, mountain bikes, and increasingly even urban hybrids are spec’ed with a single chainring on the front, and a wide gear range cassette on the rear, coupled with a single right-hand shifter. These, and bikes with internally geared rear hubs, are a bit more intuitive than the dual-derailleur system, since there is only one shift lever, and you really do get the number of gears specified, arranged sequentially. Unlike derailleurs, internally-geared systems will shift while you are not pedaling, so that when you suddenly come to a stop, you can simply shift down, and be in an easier gear when you resume riding.
Other things to remember
You don't really get 24 gears on your 24-speed bike, because some gear combinations are redundant, and other are to be avoided. When riding in the small (easy) chainring in the front, avoid shifting to the small (hard) chainring in the rear. And vice versa. These positions cause the chain to cross over and subject it to undue stress. In these gear combinations, you may hear the chain grind as it rubs the front derailleur.
Avoid shifting under torque or strain. When you need to shift, ease the pressure off the pedals somewhat to release the tension in the chain, and and gently pedal through as you shift, allowing the chain to move to the next cog.
You don't have to shift one gear at a time. Hold down the shift lever to move through the range of gears until you get to the one you want, and the chain will follow.
Bike shifters come in many shapes and varieties, with little consistency from one to the next. Some are single-lever, some are dual lever, some are twist-shift, some have numbered indicators, others don’t. The best advice I have on deciphering your shifters is to head over to a trusted shop on a day when they are not super-busy, and ask a friendly staff person to explain your shifters to you. Or, go to a quiet park and practice shifting one gear at a time while you slowly ride, and note what happens to your pedaling as you shift. Once you know how the gears operate and you've gained some practice, you will be shifting by feel in response to changing conditions.