New to mountain biking? Read our A-Z jargon buster

Read our definitive techno-pedia

Got into mountain biking and now lost in a world of jargon and acronyms? Help is at hand with our definitive techno-pedia.

>>> MBR Trail Bike of the Year 2020

A

ABP

Active Braking Pivot — Trek’s suspension design that places the seat stay pivot concentric with the rear axle. ABP helps prevent the rear brake impeding the suspension action.

Aheadset

Dia Compe’s threadless steerer/headset system that is now commonplace on all bicycles.

Air can

Short for the air canister on an air sprung rear shock.

Anti squat

Geometric configuration of the suspension to control squatting under acceleration.

Axle to crown height

The true height of a fork, measured from the dropout centre to the top of the fork crown.

Wheels Manufacturing Eccentric BB for PF30 and BB30

B

BB30

Oversized bottom bracket and crank standard.

BCD

Bolt circle diameter of the chain rings. The most common sizes on mountain bikes being 104/64mm for 4 bolt and 110/74mm for five bolt spiders.

Bob

Pedalling induced suspension compression.

Bottom out

Full compression of the suspension. Often accompanied by a metal on metal knock. Bottoming regularly usually means that the spring rate is too low.

Brain

Specialized’s inertia valve suspension technology.

Brake jack

Negative effect of braking on the rear suspension. Stiffening of the rear suspension under braking, dramatically reducing its ability to absorb bumps

Bushing

Plain bearing or sleeve of material for rotary applications. Found in shock eyelets, suspension links and telescopic forks.

Butted

Having variable thickness — usually in reference to frame tubing or spokes.

C

Cartridge bearing

A self-contained bearing assembly with inner and outer races, ball bearings and seals.

Cassette

Rear cog assembly, which slides onto the freehub body.

Cavitation

Phenomenon in dampers when a pressure differential causes the damping fluid to temporally vaporise, leading to inconsistent damping.

Centerlock

Shimano’s splined disc rotor/hub interface.

Chain device

Any system for keeping the chain in place.

Clipless pedals

Misleading term for SPD type pedals i.e. without toe clips. However, flat pedals are also clipless.

Compression damping

Damping created when the wheel hits a bump and compresses the suspension. High-speed compressions are square edge hits like roots and rocks, low-speed compressions are generated by rolling terrain or rider inputs from body movements and pedalling.

D

Damping

The dissipation of energy from a dynamic system, usually in the form of a hydraulic damper.

Detent

An adjuster click.

Dive

Compression of the front suspension under braking. Increasing the sping rate or low-speed compression damping helps combat diving.

Dot

Department of transport rated brake fluid. Usually Dot 4 or 5.1 for mountain bike brakes.

Driveside

The right-hand side of the bike i.e. with the drivetrain.

Dual crowns

Any fork with two crowns. Often called triple clamps, because each stanchion is camped at two points and the lower leg also clamps the hub axle.

Durometer

A measure of the hardness, usually in reference to tyre rubber.

DW-Link

Dave Weagle’s twin link suspension design.

E

Emulsification

When oil and gas mix in a damper (shock), causing inconsistent damping.

F

Falling rate

The force required to compress the suspension decreases as you move through the travel.

Faux-bar

Any four bar suspension design with a fixed main pivot.

FIT

Fox Isolated Technology. Closed damper design that eliminates aeration of the damping fluid.

Fork rake

Terminology for the amount by which the front axle is offset from the steering axis.

Frustum

The geometric name given to all of the tapered head tube standards.

FSR

Future Shock Rear: Specialized’s four-bar rear suspension design.

Full sus

Any bike with suspension front and rear. Short for full suspension or fully suspended.

G

Geometry

The geometric parameters of a bicycle that determine its handling.

GripShift

Sram’s lightweight twist grip shifters.

H

HammerSchmidt

Sram’s two-speed planetary-geared crankset.

Hardtail

Any bike with front suspension and a rigid frame.

Head tube

The part of the frame that carries the headset bearings and front fork.

Hollow Tech

Shimano’s two-piece hollow crank design and external bottom bracket standard.

Horst Link

The chain stay pivot on a four bar suspension design. Named after its inventor, Horst Leitner.

Hydroforming

A process were high pressure fluid is used to form complex tubing profiles.

I

Instant centre

Instantaneous centre of rotation. Basically, a virtual pivot.

ID

Internal Diameter.

Inverted forks

Opposite to conventional forks, so you have the stanchions below the upper tubes. Also called upside-down forks.

ISCG

International Standard Chain Guide mount: A standardised configuration for the three bottom bracket tabs and corresponding holes in a chain device..

ISM

Inter Spoke Milling. A process introduced by Mavic for removing excess rim material between spoke holes.

J

J-shaped axle path

Any axle path that is initially rearward than goes vertical.

K

Kevlar bead

Lightweight, folding alternative to a tyre’s wire bead.

L

Layback

The amount of offset a seatpost head has.

Leverage ratio

Direct relationship between wheel and shock travel. So a 6in travel bike with a 2in stroke shock has a 3:1 leverage ratio. It is the mechanical advantage of the rear wheel on the shock. It’s typically 3:1 on a trail bikes but some designs with long stoke shocks can be as low as 2:1.

Linear rate

The force required to compress the suspension is constant.

Linkage

A series of mechanical levers designed to change the leverage on the shock as the suspension compresses.

Lock-out

Any mechanism to switch the suspension off, by locking it in the fully extended position.

Lower legs

Also called fork lowers or lower casting.

M

Maestro

Giant Bicycles’ twin-link suspension design.

Maxle

Bolt-through quick release system from RockShox.

MCU

Micro Cellular Urethane bumpers also know as elastomer springs.

Mech

Interchangeable with derailleur, so you have a rear mech.

Mechanical discs

Disc brakes with cable, rather than hydraulic actuation.

Mineral oil

Synthetic fluid used in Shimano hydraulic disc brakes.

Monocoque

One-piece construction commonly used in aerospace engineering.

N

Nipple

Brass or alloy nut used to tension a spoke.

Non-driveside

The left-hand side of the bike, without the drivetrain.

O

OD

Outside diameter.

Open bath

Open bath dampers use the same oil for damping and lubrication, while closed cartridge units have separate damping and lubrication fluids.

P

Pawls

Spring-loaded teeth that engage the ratchet ring in a freehub.

Post Mount

Radial disc brake caliper mount, first introduced by Manitou.

Preload

Pre-compression of a spring, that increases the amount of force required to activate the suspension. Used to adjust the static ride height (sag) of the suspension.

Pull shock

Works in the opposite direction to more commonplace push shocks. So any rear shock where spring resistance and compression damping increase on the pull phase of the stroke.

Q

Q-Factor

A measure of crankset width, taken between the outer most points of the pedal inserts.

QR

Quick Release — Any lever using a cam mechanism for applying a clamping force.

R

Rebound

Suspension movement in extension.

Rebound damping

Hydraulic damping created on the rebound stroke as the suspension extends. Too much rebound damping causes the suspension to get stuck down, too little will have you bouncing up and down like a pogo stick.

Rigid

Without suspension.

Rising rate

The force required to compress the suspension increases as you move through the travel.

S

Sag

The amount by which the suspension compresses under the static weight of the rider and bike. Set by changing the spring rate and adjusting spring preload. Sag varies depending on the application, less for cross-county more for downhill, but it is typically 25-30% of the total travel on a trail bike.

Sealed bearings

Any bearing system with a seal to prevent dirt or water ingress. So, a cup and cone set-up can still be referred to as sealed bearings.

Single crown

A fork with one crown, giving a fixed axle-to-crown height.

Single pivot

Any rear suspension design where the axle path is determined by a fixed pivot.

SIS

Shimano Indexing System.

SPD

Shimano Pedaling Dynamics. Shimano’s revolutionary clipless pedal design.

Singlespeed

Bicycle with only one gear.

Split Pivot

Dave Weagle’s single pivot suspension design with a concentric rear axle pivot. Same concept as Trek’s ABP.

Spring

Any mechanical device that stores energy as it is displaced. Normally air or coil, where air springs are lighter and coil springs are more sensitive.

Spring rate

The amount of weight required to compress a spring by a given amount. So a 300lb/in coil spring requires 300lb to compress it by one inch and 600lb to compress it by two inches. Metric units are kg/mm. The lower the spring rate the ‘softer’ the spring is. Air spring rates are measured in PSI or bar. Heavier riders need higher spring rates.

Sprung mass

Everything on the bicycles that is suspended or isolated from bump forces. Includes the rider, frame and most of the components.

Squat

Rear suspension compression under acceleration.

Stanchions

Upper tubes on a conventional telescopic suspension fork.

STI

Shimano Total Integration.

Stiction

From static friction. Initial resistance in a suspension system created by seals, bushings, bearings or lack of lubrication. Less is better. Lots can seriously degrade small bump sensitivity.

Swingarm

The connecting structure between the main pivot (or pivots) and the rear axle.

T

Top-out

Full extension of the suspension. Often accompanied by a metal-on-metal knock if there is insufficient rebound damping or no bump stops.

Travel

The amount of suspension movement given in inches or millimetres. XC bikes typically have 80-100mm, Trail bikes have anything from 120 to 160mm while downhill bikes can have up to 250mm.

U

Unsprung mass

Everything on the bicycle that isn’t suspended. Wheels, rotors, fork lowers, the swingarm and a portion of the rear shock make up the unsprung mass. Basically, everything that has to ride up and over the bumps.

UST

Mavic’s Universal System Tubeless.

V

V-brake

Cantilever rim brake.

Variable rate

The force required to compress the suspension varies as you move through the travel.

Virtual pivot

Any suspension design without a fixed pivot. FSR, DW-link, VPP, VPS, Maestro, Zero all have virtual pivots or instant centres.

VPP

Virtual Pivot Point. Patent protected virtual pivot suspension design with counter-rotating links.