A glossary of essential motorcycle terms | Popular Science
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A glossary of essential motorcycle terms

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Harley Fat Bob

The Harley Fat Bob is a cruiser. Scroll down if you don't know what that means.

Harley-Davidson

Motorcycle weather is back, so pick your bike, get your license, and brush up on these common motorcycle terms.

Air-Cooled: Engines that transfer their excess heat directly to the air via cooling fins. You also see these on lawnmower engines.

Ape Hangers: Tall handlebars that require the rider to reach up, like a monkey hanging from a branch. Commonly used on Choppers.

Bikini Fairing: Small plastic wind deflector surrounding the headlight, usually with a small clear windshield on top. Commonly used on Café Racers.

Beanie Helmet: Minimal half-shell style helmet that sits on the head like a beanie. Popular with Cruiser and Chopper riders.

Belt Drive: A rubber belt that transfers power from the transmission’s output shaft to the rear wheel. Commonly used by Harley-Davidson, they are quiet and require no lubrication, but they are wider than a chain.

Bobber: A custom motorcycle with the rear fender “bobbed” off and usually with no passenger seat. They exhibit a minimalist design aesthetic.

Boxer: An engine with horizontally opposed cylinders, typically a traditional BMW, which has one cylinder sticking out from each side of the motorcycle.

Café Racer: Sporty motorcycles with low handlebars and other race-inspired modifications. Named for the British enthusiasts who were said to race their bikes from one café to the next.

Caliper: The brake component that houses sliding pistons which squeeze brake pads against the spinning brake rotors to stop the motorcycle.

Center Stand: A large stand mounted beneath the motorcycle’s frame that can swing out to lift the rear wheel off the ground, leaving the motorcycle level when parked. BMW riders with Boxer engines usually prefer these to the side-leaning side stands, because it prevents oil from running into the engine’s cylinder head on the downhill side while parked. It is helpful for when adjusting or lubricating the chain on chain-drive motorcycles.

Chain Drive: A simple chain connecting a small sprocket on the transmission’s output shaft to a larger sprocket mounted to the rear wheel hub to transfer power. It is similar to a bicycle’s drive chain.

Chopper: A motorcycle that has been modified with extended forks and has the steering head angle flattened to push the front wheel out far ahead of the rest of the bike. Choppers were a fad in the 1970s that was revived circa 2000 on the popularity of reality bike-building television shows like American Chopper and Monster Garage.

Clip Ons: Short individual handlebars for each side of the motorcycle that bolt directly to the fork tubes. Typically used on race bikes and racing-style sport bikes.

Cruiser: A motorcycle with a laid-back riding position created by tall handlebars, footpegs that mounted toward the front on the bike and usually a low seat.

Counter Steer: Pushing away on the handlebar that is on the side the rider wants the motorcycle to turn. Motorcycles don’t steer like cars at speeds above a couple miles per hour. Instead, the rider steers the front wheel away from the intended direction to initiate the turn by causing the bike to lean in the direction of the turn.

Drag Bars: Short, straight handlebars of the sort that are commonly used by drag racing motorcycles. Very similar in appearance to mountain bike handlebars.

Dual-Purpose: An off-road motorcycle that is also road-legal thanks to lights, horn, license plate and road-legal tires.

Dual Shocks: Traditional motorcycle configuration with one shock absorber and spring assembly mounted on each side of the frame to support the bike’s weight and control the motion of the rear suspension’s swing arm.

Faceshield: The clear protective shield on the front of a helmet that protects the rider from bug, gravel and other road debris.

Fairing: The plastic bodywork that protects the rider from the wind, and on sport or racing motorcycles, provides aerodynamic streamlining for higher speeds.

Footpeg: The short pegs protruding from each side of the frame for the rider and passenger to rest their feet.

Fork: The sliding telescopic tubes containing springs and hydraulic dampers that mount the front wheel to the motorcycle’s frame and provide suspension.

Full Face Helmet: A helmet with a chin bar and faceshield providing increased crash and weather protection.

Handgrip: The rubber grip on the ends of the handlebars.

Hardtail: A motorcycle that mounts the rear wheel directly to the frame with no sprung suspension. It is like most bicycles.

Helmet Hair: Matted hair that results from wearing a helmet.

High Side: When a sliding motorcycle regains traction it can catapult the rider off the opposite direction it was leaning.

Inline Four: An engine with four cylinders in a line, a layout that made its high-volume production debut with the 1969 Honda CB750 and quickly became ubiquitous (See UJM).

Kickstarter: No, this isn’t for raising money online. This is a flip-out lever from the transmission that lets the rider manually spin the engine to start it. It should really be called a jump starter, because the motion is one where the rider jumps up to bring weight back down onto the kickstarter, rather than actually using leg muscles to try to turn the engine.

Lane Splitting: Riding between lanes of stopped or slow-moving cars in places like California where this is the legal way to escape soul-crushing traffic delays.

Low Side: When a sliding motorcycle loses all traction and simply falls down in the direction it is leaning.

Master Cylinder: The hydraulic cylinders connected to the brake and clutch levers that send pressure to the brake calipers or clutch slave cylinder to actuate them.

Master Link: The removable link in the drive chain that permits the chain to be removed for service or replacement.

Open Face Helmet: A full-coverage helmet that lacks a chin bar and may or may not have a faceshield attached.

Overhead Cam: A camshaft mounted over the engine’s cylinder head that can press the valves open directly rather than indirectly using a pushrod. There is less reciprocating mass in an overhead cam valvetrain, so it can operate at higher engine speeds, permitting higher peak power in high-performance engines.

Parallel Twin: A twin-cylinder engine with the cylinders paired side-by-side. This is less expensive and more compact than a V-twin arrangement, but they aren’t balanced as well and are prone to shaking.

Pipe: Short for exhaust pipe, especially an aftermarket exhaust system added for higher performance.

Pushrod Engine: An engine whose camshaft mounts low in the engine. It activates the valves in the head by means of pushrods. These engines can be less expensive and more compact that overhead cam engines, at the expense of peak horsepower.

Rat Bike: A battered-looking motorcycle that wears its heavy use on its sleeve. Sometimes these are curated for effect, other times just the natural result of daily riding on a budget.

Rotor: The spinning brake disc that the brake caliper clamps to stop the bike.

Scrambler: An off-road-inspired motorcycle that is usually ridden on-road. These have a high-mounted exhaust and muffler and knobby tires, though they are usually for effect rather than practicality in most riders’ usage.

Shaft Drive: Some motorcycles, especially BMWs and long-distance touring bikes employ shaft drive in place of a chain or belt because of their durability. A down side is the “shaft effect” which causes the rear suspension to raise the bike when the throttle is opened and causes it to crouch lower when the throttle is closed. This can be offset by more complex rear suspension designs like BMW’s Paralever.

Side Stand: A bicycle-style kickstand that the motorcycle can lean against when parked.

Single Shock: A single rear spring and shock absorber assembly in place of the traditional dual-spring setup. It can have a longer suspension travel and benefits from the possibility of a rising-rate linkage that makes the shock dampening more effective.

Slip Ons: Higher-performance aftermarket mufflers that slip on to the factory exhaust header rather than replacing the entire exhaust system. This is usually more cost effective than a complete system, but it doesn’t maximize the potential weigh savings or power gains of a complete system.

Sport Bike: A race-inspired street-legal motorcycle, usually indicated by aerodynamic plastic fairings and windshield. These bikes have more powerful engines, better brakes and better steering than other styles, often with the compromise of a less-comfortable forward-leaning riding position that puts weight on the rider’s wrists.

Standard: A traditionally styled motorcycle with a comfortable flat seat, sensible handlebars that the rider can reach easily and footpegs directly beneath the rider to let the legs support some weight. These don’t follow any of the styling fads that come and go.

Steering Head: The pivot at the front of the frame where the fork attaches. Its angle determines the bike’s steering characteristics.

Stoppie: A hard application of the front brake that a skilled rider can employ to balance the bike on its front wheel.

Streetfighter: A sport bike with little or no bodywork. These evolved from conventional sportbikes whose riders had inflicted costly bodywork damage to otherwise rideable machines. Their solution was to put them back into service minus the damaged plastic, spawning a new design trend.

Swingarm: The moveable rear suspension component that mounts the rear wheel. Its movement is controlled by the spring and shock absorber(s).

Swingarm Stand: A separate stand for lifting a motorcycle’s rear wheel by a lever that is not mounted on the bike, but is kept in the shop. Also called a Paddock Stand, for its use on race bikes in the track paddock area.

Target Fixation: Riders’ inclination to focus on an obstacle and ride into it rather than avoiding it.

Touring Bike: Large, heavy, expensive motorcycles that are built for long-distance travel. They include obvious components like cushy seats, large-capacity fuel tanks, abundant wind protection and built-in luggage. Less-obvious details often include things like radios or reverse gear for backing these heavy machines out of parking spaces.

Twist Grip: The right handgrip controls engine speed by twisting it.

UJM (Universal Japanese Motorcycle): When the inline-four-cylinder standard motorcycle from Japan, cast in the mold of the Honda CB750, became commonplace in the 1970s, they were referred to as Universal Japanese Motorcycles. They were considered uncool at the time.

Unitized Transmission: When the motorcycle’s engine and transmission are built together, using shared oil. This is smaller and lighter than separate units, as used on larger-displacement Harley-Davidson models.

V-Twin: A twin-cylinder engine with the cylinders arranged at a v-shaped angle. This is most typical for Harley-Davidson, but other manufacturers like Ducati and Moto Guzzi have also built their reputations on V-twin motorcycles.

V-Four: When a four-cylinder engine pairs its cylinders in two banks at a v-shaped angle from one another.

Water-Cooled: High-performance motorcycles can’t shed heat efficiently enough for traditional air cooling, so they began uses automotive-style radiators to cool their engines with liquid. Since then, noise and emissions limits have driven other motorcycle types to embrace water cooling too despite the cost, complexity and styling challenges.

Wheelie: When a skilled motorcyclist accelerates abruptly enough to raise the bike’s front wheel off the ground and then ride with it balanced there.

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