It doesn’t take more than a spin around the block to realize how the gears on your bike can help you maximize your power; get going fast in a low gear and suddenly you can’t keep up with your pedals. Ride up a small hill in high gear and you’ll break a sweat with the effort.
Your gears help you ride more efficiently and consistently so you can sustain your energy.
Understanding how your bike’s gears work can help you tackle new terrain, extend your ride, build your athleticism and confidence, and choose the right components when you’re bike shopping. It will help you get the most enjoyment out of your bike.
There are five main parts of the standard bicycle that let you shift gears:
- front chainrings (a.k.a crankset)
- rear cassette
The crankset, rear cassette, chain and derailleurs are known collectively as the drivetrain.
Bikes have one, two or three front chainrings, also known as the crankset. Each chainring has teeth on it where the chain connects.
Your bike’s rear cassette is the stack of cogs mounted on the right-hand side of your rear wheel, with the small cog farthest from the wheel and the large cog closest to the wheel. Each cog teeth on it where the chain connects.
The chain connects to the teeth on your front chainrings and the cogs on your rear cassette so that when you pedal, the chainrings and cogs turn the wheels and the bike moves forward.
Derailleurs move the chain between the front chainrings or between the rear cogs. Cables run from your shifters to your derailleurs. When you press on your shifter, it moves your front or rear derailleur so the chain moves where you want it to go.
Shifters let you move the chain between your front chainrings and the cogs of your bike’s rear cassette. Each shifter controls one cable attached to one derailleur.
Gears and shifters help you maintain cadence – a constant pedaling speed. Generally, a higher cadence on an easier gear is more efficient than pedaling slower in a harder gear.
Pushing hard gears might seem faster, but it will sap your strength more quickly, and it can take a toll on your knees.
At a high cadence, you’re working in your aerobic zone, which means your muscles can clear lactic acid and postpone fatigue. The optimum cadence for road biking is around 80–100 rotations per minute. For mountain biking, it should feel like you’re spinning your legs.
Once you find a comfortable cadence, shift your gears to help you maintain that cadence for as much of your ride as you can.
Try to anticipate the terrain, and shift right before you start climbing. On flats, it’s OK to shift through several gears at a time. If you do shift on a hill, shift one gear at a time, and try to momentarily release pressure from the pedals as you’re shifting.
Proper Shifting Technique
Shift the chain between the rear cassette cogs for small changes and between the front chainrings for big changes, but not both at the same time.
When you shift, don’t pick a gear that will put your chain on opposite extremes of the front cogs and rear cassette at the same time. Called cross chaining, this is where you’re most likely to drop or break your chain.
When buying or upgrading a bike, you’ll need to decide how many gears you need, and also how your bike is geared. Both determine how hard or easy your bike is to pedal: how many times you turn the crank vs. how many times the wheel rotates.
When shopping for a bike, you’ll typically see specifications like the following to indicate the number and type of gears:
Rear cogs 11-34, 10 speed
Number of gears 30
In this example, the three numbers in the crankset (48/36/26) indicate the bike has three chainrings in the front (a triple). The specific numbers indicate how many teeth each chainring has: 48 teeth on the largest, 36 on the middle and 26 teeth on the smallest.
In the rear cogs spec, “10-speed” tells you that the there are 10 cogs in the rear cassette. The specific numbers indicate the range of teeth from the smallest to largest cog (11 teeth for the smallest to 34 for the biggest).
Because this bike has 3 chainrings in front and 10 cogs in back, it has 30 gears (3 X 10).
In your front crankset, the larger chainrings with the higher numbers of teeth are for going fast, and lower numbers are for climbing. In the rear cassette, it’s the opposite. The bigger cogs with the higher numbers of teeth are better for climbing.
What Gearing Do I Need?
The most important things to consider are your fitness level and the terrain you’ll be riding. If you’ll be riding lots of hills and you find climbing challenging, then you’ll want to opt for more gears.
If you’re a strong cyclist or you only ride flat terrain, you won’t need as many low gears to power up a hill so you can get away with fewer gears, which will keep your bike light.
Most road bikes have at least 18 gears but can have 30 or more. If you’re an average rider, it’s typically best to focus first on the low gears for climbing hills. Smaller chainrings, also called lower gears, make climbing hills easier, so you can keep your cadence consistent in hilly terrain or over longer distances.
Standard cranksets for road bikes come with two chainrings. It’s common for a standard crankset to include a 53-tooth large chainring and a 39-tooth small ring. A compact crankset has two chainrings that are smaller than the chainrings on a standard crankset to make pedaling easier when climbing hills. Compact cranksets usually have 50-tooth and 34-tooth rings, though other options are available.
If you live where it’s hilly, you will likely be happiest on a compact crankset.
Another way to alter the performance of your bike is to swap out the rear cassette. If you ride where it’s mostly flat, choosing a cassette with a narrow range, like 11-25 will let you find exactly the right gear while riding and will keep your shifting smooth. For rolling hills, a cassette with a 28-tooth large cassette will make going uphill easier. For mountainous areas, you’re going to want a really low gear, so look for a cassette with a large cog that has 30 or even 32 teeth on it. The downside to cassettes with larger cogs is that they typically have a bigger jump between gears, which can make your shifting feel less smooth and make it more difficult to find the right gear for the climb.
Gearing options for touring bikes are similar to those for road bikes. However, you’ll want to gear lower since you’ll be carrying camping gear, food and clothing.
Mountain bikers should also gear for the hardest climbs. Mountain bikes typically have 9-11 cogs in the back and 1-3 chainrings in front, indicated by 1×9, 1×10, 2×10, 1×11, etc.
Mountain bikes with single chainrings are increasingly popular. Bikes with one chainring are lighter and simpler because you’ll need only one shifter to move through the gears on the cassette.
Bike Component Quality and Price
As your drivetrain components go up in price, they typically get lighter and more precise in their performance. However, the lightest parts sometimes sacrifice durability.
If you’re considering which components to upgrade, your biggest bang for the buck will be higher quality shifters and the cables that move your derailleurs.
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