cadence - Pedaling rate or the number of revolutions per minute (RPM). Jury's still out on the ideal cadence for maximum efficiency, but cadence tends to scale with how much power you're able to put out. Perceived exertion and the preferred cycling cadence. Marsh AP, Martin PE. Medicine and science in sports and exercise, 1998, Aug.;30(6):0195-9131. The weaker someone is, the more efficient they tend to be at a lower cadence, while stronger riders are more efficient at a higher cadence.
cassette - Nope, not a throwback mixtape from the 80s. A cassette is the set of sprockets (the pyramid shaped set of gears) on the rear wheel. The chain moves up and down these gears to make riding easier or harder depending on the cyclist's needs.
century - A 100-mile ride or race. A metric century (100 km) is just over 62 miles (62.137 miles, to be exact).
chain - A loop of roller links that transfers power from the pedals to the rear wheel to propel the bike forward. If you drop your chain (i.e., if your chain slides off the gears), it's easy to put back on, but be prepared to get your hands dirty. Chain lubricant will keep your chain in tip-top shape.
chainrings - Circular metal discs with teeth that are closest to the front wheel and next to the pedals. Together they make up the crankset, which is rotated by the crank arms. Your bike can have one, two, or three chainrings depending on the bike or type of riding you do.
chainring tattoo - The grease mark some new cyclists get on their legs from accidentally bumping the chain. If this happens to you, NBD. Some dish soap or eye makeup remover will easily take care of the temporary tat.
chamois (or shammy) - Pronounced “sham-wah," chamois refers to the pad in the seat of cycling shorts that wicks away moisture, prevents chafing, and provides extra cushion. A bit of advice: Never wear underwear with chamois shorts; it'll cause unnecessary chafing and saddle sores—ouch.
chasers (or a chase group) - Nope, not a swig to wash down a shot. Chasers are riders, usually in a race, who crank away to try to catch a lead rider ahead of them.
climb - Outdoors, an actual hill or mountain. Indoors, it's when you crank up the resistance to simulate one.
clincher - A standard tire design that has a hooked, U-shaped rim and open tire casing with a tube inside. Clinchers are commonly associated with road bikes because the high tire pressure forces the lip of the tire into the rim for a super-snug fit (quite literally clinching it into place), but they can be found on all kinds of bikes.
clipless - A type of pedal that locks into the cleat of special cycling shoes for better power transfer when pedaling. This can be confusing because your shoes actually do clip (or lock) into the pedal. Cyclists used to use toe clips (little cages that go over your toes), so when ski and cycling brand LOOK invented the first pedal that didn't use toe clips, they decided to go with the term clipless.
Clydesdale - A male athlete over 220 pounds (according to official USA Triathlon Competitive Rules). This weight class (like athena) is most often found in races such as triathlon but also pops up in mountain biking and even running. The purpose of this division is to encourage participation and even the playing field, since carrying more weight is harder but also gives you a slight advantage when going downhill.
cog - Also known as a sprocket or gear, it's one of the rings in the cassette. The entire cluster of gears on the rear wheel is called a cassette or cogset.
commuter - A bike used for commuting or getting from point A to B in an urban area, sometimes called a town bike or city bike.
cornering - Basically leaning your bike to "steer" around a curve.
crank (or crankarm) - The arm that connects the pedals to the chainrings.
criterium (or crit) - A short cycling race on city streets that typically lasts less than an hour and covers 5 km or less.
cross chaining - When the chain is either 1) on the big ring in the front and the easiest (or biggest) ring in the back or 2) on the small ring in the front and the smallest (or hardest) ring in the back. This stretches the chain across the cassette and sometimes causes a weird noise. Cross chaining isn't ideal, so if you realize you're doing it, simply adjust your gears.
cycling shoes - Shoes with a stiff sole and a cleat that locks into special bike pedals, allowing for a more efficient transfer of power. These can be worn on bicycles or in indoor cycling classes. Riders who don't want to commit can opt for sneakers and toe cages (or toe straps) as a totally reasonable alternative.
cyclocross - Also known as CX or cross, cyclocross is a type of off-road bicycle racing done on an obstacle course. It can also refer to a style of off-road riding. Cyclocross bikes look similar to road bikes but have certain features (like knobby tires and disc brakes) made for off-roading. Think of it as a happy medium between road and mountain biking.