Unless you have grown up with the sport, it is tough to keep up with technological advances and, especially, the jargon used to describe them. Mountain Bike Action
adds another chapter to its compilation of “pictionaries” and tongue-in-cheek encyclopedic voyages that explore the mountain bike in all of its aspects. Much has changed since we last visited dual-suspension terminology, so buckle up, and let’s get rolling.
Trek’s acronym for Active Braking Pivot. ABP describes the pivot point between the swingarm and seatstay, designed to rotate concentric with the rear axle. In conjunction with the location of the suspension’s forward swingarm pivot and upper link, APB decouples braking forces from the suspension action. So far, APB is employed on the Select 2008 Fuel EX models and the Remedy.
Refers to any suspension that remains uncoupled from braking and pedaling forces.
Air shock (air fork): A misleading term that refers to any shock (or fork) suspended with an air spring—except in the case of Arlo Englund’s air-sprung/air-damped shocks and fork cartridges, which are licensed to Cane Creek.
Air spring: A compressed-air chamber that replaces a conventional coil spring in a shock or fork.
Air volume: A suspension term used to describe the type of spring rate that is expected from a given-sized air spring. A low-volume air-spring tends to ramp up as it compresses (rising rate). A high-volume air spring tends to be stiffer at the beginning of the compression stroke and does not ramp up as much at full compression.
Angular-contact bearing: Ball bearings that are designed to ride on specially ground races. The balls contact the inner and outer races at an angle, which allows the bearing to handle thrust (side-to-side) loading. Most ball bearings are radial-types, which are primarily designed to handle loads on a vertical plane (in line with the balls and races). Angular contact bearings are used in better-quality suspension pivots and other key points that require zero bearing play.
Anti-squat: A widely used term that describes any suspension device that prevents the rear of the bicycle from compressing—either under braking or due to acceleration forces.
Any device, usually a form of low-speed hydraulic compression damping, that is used to prevent the fork from compressing under braking forces.
Usually describes a swingarm with chainstays that are routed differently from the rear dropout to the bottom bracket pivot junction to clear drivetrain items on the right side of the frame. Also refers to a pivot or linkage that is offset to one side of the frame for clearance purposes.
ATA: Marzocchi’s Air Travel Adjust is their most adjustable air-sprung fork system that offers 1.5 inches of travel adjustment and a positive and negative air spring system.
Axle path: The invisible path that the rear axle traces as the suspension moves through its travel. Axle path is important because it affects the way the suspension responds to bumps and can alter the distance between the axle and the crankset, which causes “chain growth” and “pedal feedback.”
A line of dual-suspension bicycles which uses an
adjustable-stroke air-sprung fork that is plumbed into a small air
cylinder inline with the shock. When the fork stroke is shortened, the
eye-to-eye length of the shock is simultaneously lengthened—which rocks
the frame forward and alters its steering and seat tube angles by over
three degrees. The Bionicon rider is thus able to alter the frame
geometry for climbing or technical descending by pushing a handlebar
remote button and shifting his weight forward or back.
Bleed circuit (free bleed): A channel inside a hydraulic damper that allows some suspension fluid to bypass the rebound or compression valves. Bleed circuits are too small to pass significant volumes of fluid and thus are used to control low-speed damping. Almost all external rebound and compression adjustments control bleed circuits.
A spring-loaded valve in the compression side of a hydraulic damper that protects the shock or fork from destruction by releasing fluid when internal pressure exceeds safe levels. Blow-off valves are employed most often in forks or shocks with a lockout feature, but Specialized and Fox have used adjustable versions to moderate the effects of their inertia-valve anti-bob systems.
Bob (bobbing): The tendency for a fork or rear suspension to rhythmically compress with each downward thrust on the pedals.
Bottom-out: When a shock or fork reaches the end of its travel—usually in an abrupt manner.
Bottoming compression: A term that describes the internal valving or an external adjustment that controls the shock or fork’s resistance to bottoming out in the last stages of the compression stroke. This can be done with air-volume adjustments, such as the Scott Equalizer shock, or with a combination of air volume and hydraulic compression damping used in the Fox DHX Air and Curnutt shocks.
Bottom bracket pivot: Usually the swingarm’s forward pivot location in the area of the bottom bracket (crank bearings). Some suspensions actually use a concentric bottom bracket pivot, such as the Haro VLS (Virtual Link System).
A Specialized-coined term for its inertia-valve anti-bob fork and shock products. The inertia valve uses a spring-loaded mass (weight) which closes off the flow of shock fluid until a bump unseats it and allows the suspension to compress.
Brake jack: When applying the brake, usually the rear brake, brake jacking causes the rear suspension to extend and lift the back of the bike — a negative suspension trait.
Braking bumps: A metered series of small bumps usually found at the entrance to corners or leading to the edge of steep downhills. Braking bumps are created when a suspension or rolling wheel cannot respond to a bump at a given speed and frequency, and thus an oscillation (self-perpetuating cycle) is created. The tire bounces off the first bump and begins to create the second. Dragging the rear brake diminishes the response of the rear suspension and thus aggravates the condition that makes them.
Burping: A slang term that describes when a shock or fork is highly stressed, usually laterally (in bending), and momentarily loses air-spring pressure or leaks oil.
A simple tubular-shaped metal or plastic bearing. Most suspensions use bushings where there are sliding surfaces like shock shafts, fork lowers, damping pistons, or in the shock eyelets, where there are minimal rotation and high loads.
Caliper boss (caliper mount):
Either a flange with a pair of threaded holes (international standard) or a pair of threaded posts (post-mount) used to attach a disc brake caliper to a frame or fork.
Cartridge damper: A self-contained damping system, similar to a slender shock, that is inserted into a fork. Cartridge dampers can be manufactured under stricter controls to increase reliability, are easier to service, and are lighter weight than damping systems which are assembled directly into the fork sliders. Marzocchi and Manitou use cartridge dampers throughout their fork lineups.
Chain growth: A slightly misleading term that describes the action of suspensions with axle paths that move away from the bottom bracket as they compress. Excessive chain growth can be felt as a counterclockwise tug on the crankset as the suspension compresses and the taut, upper side of the chain unrolls slack from the derailleur side. Some designers use a moderate amount of chain growth to firm up the suspension under power, because chain tension acts to resist the suspension in compression and thus counteracts bobbing.
Any device, usually fixed to the bottom bracket, that encircles the crank’s chainring to prevent the chain from derailing over rough terrain. Most are made from four parts: the “boomerang” is the mounting plate fixed to the frame; the “bash guard” is either a ring that bolts onto the outer sprocket location or a thick plastic plate below the chainrings; the lower roller guide, which forces the chain to wrap around two thirds of the sprocket’s diameter; and an upper guide which can be a second roller or a derailleur-cage-type arrangement. There are three standards for mounting chain guides: the bottom bracket mount is simply held in place by the right-side thread-in bearing cup; the ISCG (International Standard Chain Guide) uses three bolts on a 2-5/16-inch bolt circle (59.24 millimeters); and the ISCG-05 uses three bolts on a larger-diameter, 2-7/8-inch (73-millimeter) bolt circle.
Chatter bumps: Any rapid series of small-to-moderate sized bumps that typically defeats bicycle suspension and causes the bike to skip over the terrain (similar in effect to braking bumps).
Clicker: Any adjustment knob or lever that has an indexing detent. Typically, the low-speed rebound and compression dials of a fork or shock are called “clickers.”
Coil-over shock: Any shock which uses a coil-type spring.
Coil spring: Any spiral-wound spring, usually steel alloy or titanium. Coil springs are usually marked with two values: the first is the designated travel; the second is the spring rate in inch-pounds. For instance, a 1.75 x 650 is for a 1-3/4 inch-stroke shock, and the spring rate is 650 pounds for every inch the spring is compressed.
Also called an IFP (internal floating piston), it forms a moving barrier inside the damper between the suspension fluid and a compressed gas chamber. The compensating piston makes room for the extra volume of the damper shaft as the shock is compressed.
Friction, usually hydraulic fluid forced through various valves, used to control the fork or shock’s rate of compression. The primary reason for compression damping is to slow the damper near the end of its stroke to prevent harsh bottoming (high speed compression), and to maintain a certain ride height for better cornering and braking (low-speed compression).
Curnutt damper: A patented, pneumatically controlled compression valve that is adjusted by manipulating the internal pressure of the damper’s compensating chamber. Perfected for bicycle use by Charles Curnutt Jr. and Brent Foes, the Curnutt shock effectively controls suspension bobbing, and its pressure-activated damping piston automatically ramps up to control bottoming as the shock is compressed.
Damping: Force, usually hydraulic friction, used to dissipate the energy of an impact or subdue the rebound and compression speed of a fork or shock spring so the suspension will return to its preset ride height. Damping prevents oscillation which, in the case of suspension, is a condition where each successive impact adds energy to the spring until the suspension bounces uncontrolled between full compression and full extension.
Damper: It is the shock body, the fork cartridge or the assembly inside the fork that contains the hydraulic damping mechanism (or air damper in the case of Cane Creek’s Englund shocks and fork replacement cartridges).
Damping curve: The resistance generated by a damper throughout its stroke, expressed as a graph, forms an S-shaped curve.
Default settings: The manufacturer’s recommended spring pressure and damping values for a given rider. Many forks and some shocks have their default settings printed near the adjustment controls. The rest are available on the suspension maker’s websites or in the owner’s manual. It is worth your while to memorize your default settings, or write them down where you can access the information on the trail, so you won’t have to sweat it if an experimental setup turns sour.
Dropout pivot: Where a seatstay pivots above the rear axle on the dropout. Dropout pivots are most commonly found on single-pivot swingarm suspensions, which are the predominant type.
DU bushing: The Garlock DU bushing is the workhorse of the suspension industry. It is a steel strip that is coated with sintered bronze particles and then impregnated with a slippery Teflon mixture. The strip is rolled into various sized tube shapes and becomes a self-lubricating bearing that fits almost anywhere. DU bushings are most common in shock eyelets, damper assemblies and fork sliders, but suspension designers still use them in linkages and dropout pivots when weight savings take precedence over long-term durability.
Dual Air: A RockShox term for its separately adjustable positive and negative air springs, used on its upper-end air-sprung forks.
Dual crown: Any fork with a pair of crowns, one on either side of the frame’s head tube (motorcycle style). The advantage is that the dual-crown fork puts the head tube bearings and fork steerer tube in shear, and imparts much less bending moments in those critical areas.
Dual-link suspension: Any type of rear suspension that uses a pair of links to rock the swingarm instead of a fixed pivot. The most popular dual-link suspensions are the Intense VPP, Giant Maestro, Marin Quad-Link 2.0, Rocky Mountain ETSX, and the dw-link.
Dust wiper: The external plastic seal that forms the first line of defense to keep crud from attacking the air and oil seals inside a fork or shock. The dust wiper is usually visible where the fork stanchion tube enters the slider assembly, or the shock shaft plunges into the damper body. The fork’s dust wiper can be removed to be cleaned and lubricated.
A dual-link suspension configured to create a vector of acceleration upwards from the tire’s contact patch, through the general area of the frame’s head tube. Dave Weagle (that’s the DW part) patented the concept as it is used to counter the tendency of the rider’s mass to rock rearward and compress the rear suspension with each forward acceleration of the bicycle. Weagle also popularized the term “anti squat,” which defines the action of the dw-link.
Elevated swingarm (elevated chainstay): Any swingarm that is routed above the drive side of the chain.
Ending-stroke compression: Usually refers to an adjustment that increases the compression damping forces as the shock or fork nears the end of its travel. Ending-stroke compression is used to prevent bottoming after a hard impact without causing the damper to ride harshly through the majority of its stroke. The Fox DHX ending stroke adjustment is the threaded blue cap on the piggyback reservoir.
Felt Racing’s adaptation of the dual-link rear suspension, which uses a fifth member called the Equilink: a vertical strut which ties the upper and lower linkages together and controls the system’s anti-bob function.
ETA: Extension Travel Adjustment is Marzocchi’s first and most successful fork retraction device. Twisting the crown-mounted lever shortens the fork travel, but still leaves about an inch of movement to save your skin if you hit a rough section in lockout mode.
ETSX: Rocky Mountain’s Energy Transfer System is their dual-link rear suspension design which uses long, forged aluminum links in an elevated chainstay configuration. The ETSX system uses chain growth to effectively control bobbing forces and has been one of the most successful dual-suspension cross-country designs in marathon competitions.
Eye-to-eye length: The distance from the center of each end of a shock measured from the centers of the mounting holes (shock eyelets).
Falling rate: A lever or linkage arrangement that creates an increase in moment (mechanical advantage) as the suspension advances through its stroke. A falling-rate makes it easier for the suspension to compress the shock as it gets closer to the end of its travel, and is generally used to offset the natural tendency for an air spring to become progressively stiffer as it is compressed.
Flex pivot: Used mainly at the rear dropout where flexible frame members, usually the seatstay and chainstay, are used to replace a swiveling mechanical pivot. Ibis, Gary Fisher and Trek popularized this concept.
Floating brake: As it relates to bicycles, a disc brake caliper that is mounted to a plate that rotates freely around the rear axle. A linkage rod extends from the caliper mount to the frame where it is located to neutralize braking torque. Floating brakes are, in effect, a four-bar linkage designed to uncouple braking forces from suspension. Moving the location of the linkage rod, however, is sometimes done to cause the suspension to extend or compress under braking.
Fluid flow damping: A higher-volume, lower-pressure version of Manitou’s twin-piston (TPC) damping cartridge.
Four-bar linkage: An overused phrase that encompasses all dual-link designs (VPP, Maestro, dw-link); and Horst Link-types like Specialized’s FSR and Ellsworth’s ICT. Three of the “bars” are the lower arm (usually the swingarm), the upper arm (typically a rocker link that pivots on the seat tube) and a seatstay with the rear dropout attached to it (the triangulated swingarm, in the case of a dual-link design). The front section of the frame forms the fourth bar. If the rear axle is attached to a swingarm that pivots directly from the frame, it is not a true four-bar suspension—regardless of how many rockers and links it takes to move the shock.
FSR: Specialized Bicycle’s acronym (Future Shock Rear) for its four-bar Horst Link rear suspension, which uses a seatstay-mounted rear dropout and has a swingarm pivot below and in front of the rear axle. Licensees of the patented Horst-Link design are required to post an “FSR” suspension sticker on the rear suspension.
Hex Lock: Manitou’s name for its patented, six-sided through-axle dropout interface. The hexagonal sections form a torsion barrier at the dropout and increase steering stability for Manitou’s downhill and big-drop forks like the Dorado, Sherman and Stance.
A suspension that uses a dropout fixed to the seatstay and a rear swingarm pivot below and forward of the rear axle. The design was invented and patented by Horst Leitner and is widely used to uncouple braking and chain tension from the rear suspension. Specialized owns the rights to the patent.
ICT (Instant Center Tracking): Tony Ellsworth’s name for a four-bar link suspension with an “instant center” that occurs ahead of the bicycle’s front wheel. Ellsworth patented the concept as a method of creating a more efficient-pedaling rear-suspension bicycle.
Chain idler: Any roller that guides the chain. More specifically, a frame-mounted roller guide, pioneered by Canada’s Balfa Cycles and used on the upper run of the chain to reduce or eliminate the effect of chain tension on the rear suspension.
Inertia valve (mass valve): Used by Specialized on its Brain shock and fork, and until recently by Fox inside its X-forks, the inertial valve is basically a weighted valve which closes off the flow of suspension fluid in compression. When a bump moves the bike upwards, the weight appears to slide downwards and unlocks the suspension (the spring-loaded weight actually tries to remain in the same place). A properly operating mass-valve is the ultimate anti-bob weapon.
Instant center: Four-bar linkages tend to arc around an imaginary pivot point that migrates as the linkage cycles through its stroke. This point is called an “instant center,” and can be found where the lines through the centerlines of the upper and lower linkage pivots intersect in space.
IT (Infinite Travel-adjust): Manitou’s travel adjustment mechanism for air-sprung forks, featured on the Nixon, Minute, Scarab and Black forks.
The resistance of a frame, suspension, and wheels to side loading. Typically, banging through rocks, tail slides, and putting your full strength on one pedal generate lateral stress in the bicycle.
Maestro: Giant Bicycles’ name for its second-generation dual-link rear suspension, used throughout its upper-end lineup for both cross-country and downhill.
Magic Link: An ill-fated design invented by Brian Berthold and pioneered by Kona, the Magic Link was a vertical lever in front of the bottom bracket that the swingarm pivoted on. Chain tension drove the link forward, while braking and bump forces pulled the lever to the rear of the bike. The suspension’s rocker-driven shock was mounted to the top of the Magic Link, so that the fore-aft movement of the link changed the shock’s rate and also the suspension travel. The result was an automatic shift from shorter-travel, firm pedaling for climbing to longer-travel, supple suspension for descending. It is no longer used by Kona.
Maxle (Maxle QR):
A quick-release, 20-millimeter-diameter through-axle designed by RockShox for its forks, and later as a smaller-diameter rear-axle option. The quick-release version is threaded into the left side dropout, and when latched, expands to capture the unthreaded bores of both the right- and left-side dropouts. Maxle and Maxle QR axles are featured on their jumping and gravity-oriented forks like the Pike, Lyrik and Boxxer.
Mission Control: RockShox term for its top-of-the-line fork damping system, with separate controls for high- and low-speed rebound and compression.
Motion Control: A RockShox term for the adjustable hydraulic pedaling platform/lockout function of its shocks and forks.
Negative spring: Used primarily for air-sprung forks and shocks. Because air springs have a large amount of static pressure at the beginning of the stroke, a negative spring acts against the main air spring at full extension to soften the initial spring rate. The stronger (higher pressure) the negative spring, the softer the suspension will ride in the first 20 percent of its stroke. Negative springs can be pneumatic, coil types or even closed-cell plastic foam. Coil-sprung forks and shocks don’t require negative springs because a coil-spring has no stored energy when it reaches full extension.
An oversized-diameter (1.5-inch diameter) fork steerer that requires a corresponding larger headset and frame head tube. OnePointFive was championed by Manitou and is designed to strengthen the steerer tube interface without a significant weight penalty, and to facilitate longer-stroke, single-crown forks.
Pack up (Packing): Suspension packs up when excessive rebound damping prevents the suspension from returning to its preset ride height after successive impacts. An imbalance between the fork and shock is also a common cause. For instance, a stiffly sprung fork with excessive low-speed compression will drive the rear suspension low in its travel over chatter bumps. Because the affected suspension is partly compressed, it will ride stiffer and bounce over even moderate-sized bumps.
Piggyback reservoir: A tubular chamber, with a gas-charged internal piston, mounted alongside a shock that is used to bleed off internal pressure caused by fluid displaced by the shock shaft in compression. Most shock designers use the channel between the body and reservoir for the low-speed compression
PopLoc: RockShox term for its pedaling-platform/lockout control.
ProPedal: The name for the Fox Racing Shox pedaling platform damping for anti-bob control.
Marin’s novel-looking dual-link suspension, designed by Englishman John Whyte, operates a stiff, monocoque swingarm on a pair of diminutive levers.
RA (reverse arch): Manitou’s reverse fork arch requires less material and, because its position allows the arch to make a more direct path between the fork sliders, it is marginally stiffer than a conventional forward-facing arch.
RC3: Marzocchi’s best damping system, with all of the bells and whistles, used on its gravity-oriented fork lineup.
Rapid Travel Adjust: Manitou’s infinitely adjustable travel device (within a 1.7-inch range) for its air-sprung forks also has a handlebar-remote feature. “Rapid Travel II” is a two-position version that alters Manitou’s Sherman forks by 1.5-inches with a fork-crown-mounted dial.
Rebound damping: The most important function of a suspension, rebound damping is used to slow the return rate of the suspension to prevent the spring from bouncing the rider or bicycle upwards after each compression episode. Rebound is divided into high-speed and low-speed damping. High-speed rebound is built into the damper piston and is rarely externally adjustable. High-speed rebound is set to control the return speed of the suspension when it is nearly or fully compressed and the return spring pressure is greatest. Low-speed rebound is almost always adjustable with an external clicker and is used to fine tune the suspension’s return rate for rolling bumps (slower) or rocks and chatter (faster) and to fine-tune the return rate for significant changes in air-spring pressure.
Rising rate: A linkage or suspension with a reduction in moment (mechanical advantage) as it advances through its stroke. Less moment means that the shock’s spring and damping become harder to compress as the suspension moves closer to the end of its stroke. “Rising rate” can apply to a spring, as in the case of air springs, which become progressively stiffer as they are compressed, and also to special damping circuits which react in similar fashion. Rising-rate suspension is primarily used to resist bottoming while allowing the suspension to remain supple through the main part of its stroke.
Rocker (Rocker Link):
Also called a “walking beam,” any link with a pivot on either end and a fulcrum between them. Rocker links most often pivot on the seat tube and connect the seat stay to a bottom-bracket-mounted shock (like the Turner 5 Spot and Kona Stinky).
RP23: Fox air shocks with two concentric platform adjustments. The blue platform-adjustment dial is preset for one of three different platform levels. Once set, the longer ProPedal lever simply switches the platform on or off. The Fox RP23 sets the standard for cross-country air shocks.
Sag (negative travel): The measured amount that the shock and fork are allowed to settle under the weight of the rider and bicycle. Most suspension makers call for 25 to 30 percent of the fork or shock’s stroke. The reason for sag is to allow the suspension to drop into a depression or react to a negative G situation to keep the wheel in contact with the ground at all times.
SSA: Marzocchi’s acronym for a Single Schrader Air valve which inflates both the positive and negative chambers of its air-sprung forks.
Shock stroke (fork stroke): The actual distance that the shock or fork compresses.
The basic rear suspension. “Single pivot” is any type of suspension that begins with a frame-mounted pivot and extends to and incorporates the rear dropout. Examples are Kona, Orange, Gary Fisher, the Santa Cruz Heckler and Superlight, and Cannondale.
Sliders (lowers): The moving part of the fork attached to the axle. Normally, the sliders are cast aluminum or magnesium and are reinforced with a connecting arch. Inverted fork sliders are tubular and extend into the larger-diameter uppers.
Solo Air: RockShox term for one Schrader valve that fills the positive and negative side of the fork’s air springs at the same time.
Spring rate: Usually, the force required to compress a spring one inch, measured in pounds. (A 650-pound spring needs 650 pounds to compress it one inch). Any ratio of force divided by a measured distance of compression will do.
SPV: “Stable Platform Valving” is Manitou’s term for their anti-bob suspension technology that is primarily controlled by internal pneumatic pressure and adjustable via an external Schrader valve on the fork crown or shock body.
Square-edged bump: The anathema of suspension tuners is an abrupt, vertical acceleration (like a big sidewalk curb) that exceeds the suspension’s compression damping forces and bottoms the suspension. Most damping systems and suspensions cannot handle the violent acceleration and high shaft speeds that a square-edged impact generates because it would require so much compression damping that the bike would ride board-stiff over everything else. The best shocks and forks use adjustable bottoming compression damping circuits to handle as much of a square-edged impact as possible.
Any force that causes the rear suspension to compress abnormally while riding. Sources of suspension squat are the rider’s mass rocking back as a reaction to forward acceleration, rear braking torque action through the suspension members, an over-sprung fork or one with too much compression damping, or chain tension acting on the suspension.
Stanchions (stanchion tubes) :
Normally, the upper tubes of a fork that are attached to the fork crown. In the case of an inverted fork (Foes, Manitou Dorado), the stanchions are still the upper section of the fork, because they are fixed to the crown.
Stiction: A contraction of “static friction,” which is related to the initial breaking force required to move a stationary object. Stiction is created by friction between the sliding surfaces inside the shock and fork, (the seals and bushings) and by the starting forces required to open the valves in the damping circuits. Additional stiction is generated by the bearings in the suspension linkages. Starting friction is the enemy of suspension, because it starts and stops twice each time it reacts to an impact. The greater the stiction, the harsher the suspension will feel.
Spherical bearings: Drag racers call them “rod ends.” Spherical bearings are used in high-quality shock eyelets because they can rotate to a degree inside their housing and thus are self-aligning. DT Swiss uses them in their shock lineup and Specialized uses spherical bearings in the Epic series Brain Shocks.
Strut (Cannondale Lefty):
A fork has to have more than one blade, so Cannondale’s single-sided Lefty front suspension is called a strut—just like the ones on the nose of an airplane.
TALAS: Stands for Travel Adjustable Linear Air Spring, and it is a Fox Racing Shox term for an adjustable-travel device used on its air forks. TALAS is unique in that the spring rate remains correct at each ride height setting and, once it is set, the fork will power itself to the new travel selection as it is being ridden.
Thru-axle: Through-axles are usually 20-millimeter tubular axles which are clamped, motorcycle-style, to heavy-duty fork dropouts. The lateral rigidity that they add to a fork is an inflated but real benefit. Thru-axle rear hubs and frames are popular among downhillers, although they are smaller—ten to 12 millimeters in diameter.
TPC (Twin Piston Chamber): Manitou’s cartridge-type fork damper that uses separate rebound and compression pistons.
Marzocchi’s fork-crown-mounted adjustable compression damping dial.
2-Step Air: Another RockShox travel-adjustment system that shortens its long-travel, big-hit forks by 1.7 inches with one click of a crown-mounted dial.
U-Turn: RockShox’s term for the adjustable-travel function of its coil-spring forks. “U-Turn Air” is the term for its air-sprung forks.
VLS (Virtual Link System): Haro’s dual-link suspension, designed by Neal Sakai to prevent bobbing and yet remain supple, it originally appeared on the Sonix model. The lower link is concentric with the bottom bracket axle and, because the cranks are connected to the rear triangle, the drivetrain is not affected by the suspension action.
VPP (Virtual Pivot Point): As it applies today, a dual-link suspension originally designed by James Klassen to use chain tension to prevent pedal-induced bobbing in the initial stage of suspension travel. VPP suspension is unique to its dual-link cousins in that the upper and lower links operate in opposite directions. Both Santa Cruz and Intense are authorized to use VPP.
VPS: Norco’s acronym for its most successful rocker-link suspension, used throughout its line, from downhill racers to aggressive trailbikes. VPS is a true Horst-Link-type, four-bar system.