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It would be helpful to have a common place to list terminology, I'll start it off

Some Rules

  • Make sure you only put one term per answer!
  • Try to include an image if applicable
  • Include sources that contain detailed information

Also, I made this a community wiki, so that anyone will be able to edit it, and to stop rep-hoarding


There's a handy reference at the Park Tool Co. website, a bike repair map; it's a diagram of a bike with all the parts labeled, and is very handy! At the moment, the diagram is up at parktool.com/blog/repair-help. (They've changed the URL in the past, so this link may break.)


Edit: This page is meant to identify what things or concepts are (as per this thread in meta). If you want to recommend an accessory or a specific product you've found handy, please use the accessories page.


Contents: (As of 03 Nov 2012)

Bearing
Bottom Bracket
BSO/Bike-Shaped-Object
Brifter
Cable Stretcher
Cable Pull
Cadence
Chain Gauge
Chain Tool
Chain Tug/Chain Tensioner
Chainstay Length
Chamois
Clipless Pedals
Crank
Derailer Hanger/Derailleur Ranger
Disc Hub
Door Zone
Dunlop Valve
Fender/Mudguard/Mudflaps
Fixed-Gear
Flip-Flop Hub
Frame
Folding Bike
Gear Inches
Groupset
Handlebars
Headset
Hose Clamp aka Jubilee Clip
Hub Skewer
Hub
Internally-Geared Hub
Lawyer lips/lawyer tabs
LBS/Local Bike Shop
Luggage Carrier/Rack
Master Link
Mixte
Mountain Bike
Pannier
Power Meter
Presta Valve/Presta Tube
Quick-Release
Rim
Saddle
Saddlebag
Schrader Valve/ Schrader Tube
Skewer
Spoke
Stem
Tire Lever/Tire Iron
Track Pump/Floor Pump
Triathalon Bars/Triathlon Bars

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4  
one term per answer would be beneficial –  dotjoe Aug 26 '10 at 13:51
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Should we add an "Anything not mentioned here" link? (With a link to sheldonbrown.com/glossary.html, of course.) –  jensgram Aug 26 '10 at 15:22
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Is there a way to link to a specific answer, so that in future questions you can use one of these terms and link to it for reference? –  Kevin Aug 26 '10 at 16:13
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Kevin: Under the bulk of the answer, there is a 'Link' hyperlink, which will link to the answer (its right above comment) –  Dan McClain Aug 26 '10 at 17:12
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@MarkIngram: useful things that aren't atually questions are what community wikis are for. –  freiheit Sep 12 '10 at 17:47
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53 Answers

Clipless pedals

AKA clip-in or step-in

Clipless pedals are pedals that require a special cleated cycling shoe that locks the shoe into the pedal. Clipless refers to the pedal not having a toe clip. There are two major kind of clipless pedals, LOOK and Shimano Pedaling Dynamics (SPD). To release clipless pedals, the rider typically twists his/her foot.

Toe Clips

Clipless pedals are called clipless - even though you do clip onto them - because avoid the need for toe clips and straps. pedal with toe clip and strap

LOOK Pedals

LOOK pedals came first and were inspired by ski bindings. LOOK pedals are commonly used on road bikes. A similar (but not compatible) pedal system is Shimano's SPD-SL system.

LOOK Pedals

SPD Pedals

Shimano Pedaling Dynamics or SPD pedals use a cleat that is recessed into the shoe. This allows the rider to walk normally, which is why this pedal is commonly used with mountain bikes, where the rider may have to walk short distances over some obstacles. Note that Shimano's SPD-SL system is not compatible with SPD.

SpeedPlay Pedals

SpeedPlay Pedals

Crank Brothers 'Eggbeaters'

Crank Brothers Eggbeaters

This answer draws heavily from http://en.wikipedia.org/wiki/Clipless_pedals#Clipless_pedals

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1  
Added a link to clip+strap pedals, mainly to explain why clipless pedals have clips! –  mgb Feb 9 '11 at 5:20
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LBS

LBS is the acronym commonly used for Local Bike Shop. The term is usually used when comparing small, privately owned shops with large chains, big box stores, and internet shops.

http://www.flickr.com/photos/johnprolly/5728618798/ http://www.flickr.com/photos/johnprolly/5728618798/

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Triathlon bars or Aerobars

Aerodynamic bike handlebars are for racing bicycles and particularly time trial bicycles.

Included are narrow, bolt-on extensions that draw the body forward into a tucked position, pursuit bars that spread the arms of the rider but drops the torso into a slightly lower position, and integrated units that combine elements of both designs.

Triathlon bars are commonly used in triathlons and time trial events on road and track. However, they are illegal in most mass start road races or any other event where drafting is permitted because, while aerodynamically advantageous, they tend to draw the hands away from brakes, make the rider slightly more unstable on the bike, and can be dangerous in the event of an accident. Further, they are not useful in sprints or shorter climbs where power is of greater importance than aerodynamics.

There is a distinct set of aerobars that are utilised in draft legal triathlons on regular road frames. As draft legal (ITU sanctioned) triathlon races require road frames that are UCI legal, a stubby pair of arms has been developed for this style of racing.

alt text

Sources:

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Folding Bike

AKA Folder

A bike that's designed to fold down to a small package without disassembly. They usually have smaller wheels, and are designed to be taken on trains and buses. Many transit organizations that don't allow bikes during peak hours will allow folding bikes during these busy times. They also reduce storage space requirements, often useful in city apartments.

There are also bikes that do not fold, but are designed to be taken apart easily, with frame latches, quick-release latches, or hybrid folding/unlatching systems.

Folding bike, ready to ride

Folding bike, ready to ride

Folding bike, in folded position

Folding bike, in folded position

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Stem

Attaches the handlebars to the bike, or, more precisely, to the steer tube (when using a threadless headset) or fork (when using a threaded headset). Many different sizes and angles of stems are available, so that the rider can place the handlebars where they will be the most comfortable during riding. There are also adjustable stems made, so the rider may change bar positions without removing the handlebars.

More information at Sheldon Brown's site

Adjustable stem

Adjustable stem on a touring bike, attached to the headset with risers, with the handlebars removed

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Fixed-Gear

AKA: Fixie

A fixed-gear bike has the rear gear locked to the hub, which fixes the pedals rotation to the rear wheels rotation. In other words, you can't coast: The pedals are always in motion as long as the bike is. Track bikes are commonly fixed-gear.

The sprocket is screwed directly onto a fixed hub. When the rear wheel turns, the pedals turn in the same direction. This allows a cyclist to stop without using a brake, by resisting the rotation of the cranks, and also to ride in reverse.

flip-flop hub on fixie setting

The hub in the picture is a flip-flop hub.

More information: http://en.wikipedia.org/wiki/Fixed_gear

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Presta Valve / Presta Tube

aka Sclaverand valve or French valve

Presta valve photo credit

The Presta valve is a valve commonly found in high pressure road style and many mountain bicycle inner tubes. The air pressure in an inflated tire holds the inner valve body shut. A small screw and captive nut on the top of the valve body permits the valve to be screwed shut and ensure that it remains tightly closed. The nut must be unscrewed to permit airflow in either direction (this must be done before attaching a pump). The screw remains captive on the valve body even when unscrewed fully; it is tightened again after the tire is inflated and the pump removed.

A Presta valve adapter can be used to fill a Presta tube with a normal Schrader-style air pump, although many pumps today come with a built-in adapter. These adapters can be purchased at almost any bike shop.

For a video tutorial on the use of the adapter, check out this video at BicycleTutor.com

More information: http://en.wikipedia.org/wiki/Presta_valve
Go to Schrader valve.

alt text

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Schrader valve/Schrader tube

aka "American valve" or "car valve"

alt text

The Schrader valve consists of a valve stem into which a valve core is threaded, and is used on virtually all automobile tires and most wider rimmed bicycle tires. The valve core is a poppet valve assisted by a spring.

A valve cap is important on a Schrader valve because if one is not fitted, dirt and water can enter the outside of the valve, potentially jamming it or contaminating the sealing surfaces and causing a leak. Rock salt and other chemical deicers used in the winter are especially damaging for the brass components in the Schrader valve.

Schrader valves are almost universal on car tires, meaning you can often (carefully) inflate your bike tires with the air machines at roadside garages.

For an instruction video on patching and inflating a Schrader tube, check out this video on BicycleTutor.com.

More information: http://en.wikipedia.org/wiki/Schrader_valve
Go to Presta Valve

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1  
I don't think it would hurt to combine this one with its sibling answer –  Joe Philllips Sep 6 '10 at 17:51
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In the UK at least this can also be referred to as the 'car type' since it's common to our car tyres. It's quite useful to use this type of valve because it means you can get your tires pumped up at petrol stations. –  Colin Newell Mar 3 '11 at 17:24
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Handlebars

The part of the bike you hold onto. When you turn the handlebars, the front wheel turns with them. The front wheel is held in the fork, which ends in a steerer tube, which in turn attaches to the stem, which clamps onto the handlebar.

See this question for more information about handlebar types.

Additional information:

Sheldon Brown on handlebars, drop bars, and upright bars.

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Pannier

A pannier, pronounced pan-yer /ˈpanyər, ˈpanēər/ (US) or pan-i-er /ˈpanɪə/ (UK) [1], is a bag designed to be mounted on the side of a bicycle rack. Bags can be made of nylon, canvas, or waterproof materials such as PVC. Rear is most common, but smaller panniers intended for a front rack are also available.

Often erroneously called a saddlebag because a pannier on a motorcycle or horse is attached to the saddle.

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It's an English word that's commonly mistaken for being a french word. It's pronounced "PAN-yer", but many people say "PAN-yay". –  freiheit Sep 12 '10 at 18:04
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Saddlebag

(a.k.a. seat bag, wedge bag, etc.) Small bag designed to be attached to the underside of a bicycle saddle, usually large enough to hold tools to change a flat tire.

The name "saddlebag" is often mistakenly applied to panniers which resemble saddlebags used on motorcycles or horse saddles.

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Quick-release

The term "quick-release" - often abbreviated as "QR" - usually refers to a quick-release axle, a device that allows the removal of a bicycle wheel without tools.

alt text

Quick-release axle

"Quick-release" also refers to several other types of quick-release mechanisms that are popular on folding bicycles, such as collapsible seatposts and folding frames.

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The quickness of the release is defeated on most bikes by extra lugs that force you to unscrew the axle almost fully to remove the wheel. They are supposed to stop the wheel falling out if the release comes loose - but they are really to stop you sueing and so are called lawyer-lugs –  mgb Oct 22 '10 at 3:51
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Cadence

Cadence is the number of revolutions of the crank per minute.

Cyclists typically have a preferred cadence at which they feel most comfortable, and on bicycles with many gears it is possible to stick to a favourite cadence at a wide range of speeds. Recreational and utility cyclists typically cycle around 60–80 rpm; racing cyclists around 80–120 rpm and sprinters up to 170 rpm for short bursts. The professional racing cyclist and Tour de France champion Lance Armstrong is known for his technique of keeping up high cadences of around 110 rpm for hours on end to improve efficiency1

1 http://en.wikipedia.org/wiki/Cadence_(cycling)

If you are getting pain in your knees, it could be that your cadence is too low. A cadence between 80-100 will probably reduce knee pains, as stated in bicycling.com or more detailed at Cycling Performance Tips web site.

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We're really not here to copy and paste from Wikipedia. Are there recommended cadence rates for beginners? What users are generally concerned with cadence? Perhaps you could address concerns like these? –  Neil Fein Sep 2 '10 at 23:11
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Hose Clamp

A.K.A. Jubilee Clip

A ratcheting clamp often used to attach items to a bicycle fork or handlebars.

Flashlight attached to flat handlebars with a series of hose clamps.

Flashlight attached to handlebars with a series of hose clamps.

Jubilee Clip on Wikipedia

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1  
I see how the clamp goes around the torch, but how does it attach to the bars? Is there a second clamp, or does it twist around? –  Hugo Jun 20 '11 at 8:59
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Hose clamps can cut into paint an even metal if they're tight enough. You can stick a strip of old inner tube under the clamp to prevent this (and to provide better grip). –  naught101 May 12 '12 at 3:03
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Cable Stretcher

A.K.A. "Fourth Hand" brake tool

a

The cable stretcher is used to stretch brake cables when installing brakes or new cable. It can also be used to tighten zip ties.

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1  
I have never had problems installing brake cables with a standard set of pliers. –  Ian Sep 17 '10 at 9:22
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@neilfein, I tend to solder the ends of cables after I have cut them to stop any fraying. –  Ian Feb 9 '11 at 11:37
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Rim

The circular, U-shaped (in cross-section) part of a bicycle wheel that the tire and spokes are is attached to. Wheel-building is the process of attaching a hub to a rim with spokes; the name has connotations of smaller runs of wheels that are not machine-built, and are of presumably higher quality.

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BSO

Bicycle Shaped Object: A derogatory term for a very cheaply produced bike aleged to have very low quality components which can break when attempting to adjust them:

alt text

For instance the BSO pictured is being sold in the UK by ASDA (owned by Walmart) for £75. These bikes tend to be mass produced and sold in flat pack boxes which must be assembled.

As purchasers in this market may often be inexperienced or ignorant, many BSOs carry features which are included for marketing purposes but are unnecessary for the typical end-user. Such features may include front and rear suspension, wide off-road style tyres and an excessive number of gear ratios. Their inclusion reduces the budget available for other components and may not increase the BSO's functionality.

It is more advisable to search for a cheap second-hand bike in a similar price range from a more experienced cyclist or on eBay than to go for one of these.

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"An impassioned guide on why not to buy a cheap Bike or BSO" southcoastbikes.co.uk/articles.asp?article=NO_BSO –  Hugo Jul 17 '11 at 18:04
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Dunlop Valve

aka Woods valve or English valve

The Dunlop valve is an older style valve that is no longer commonly found in the english speaking world. A pump designed for a Presta valve can be used to fill a tube with a Dunlop valve.

Dunlop Valve

More information: http://en.wikipedia.org/wiki/Dunlop_valve
Go to Presta valve.
Go to Schrader valve.

Also see this answer.

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This is the most common valve on everyday usage bicycles in The Netherlands –  jilles de wit Oct 19 '10 at 7:40
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Door Zone

The area next to parked cars that a suddenly opened door would cover. A hazard that you should avoid.

enter image description here

Satirical portrayal of Santa Monica bike lane design; it illustrates the "door zone" concept well.

Cycling in the Door Zone reduces your ability to react to hazards emerging from the space between parked vehicles. These may include unobservant pedestrians, inadequately restrained dogs (whose leads can reduce your options), sports equipment and children chasing sports equipment.

Drivers entering the road from a driveway, forecourt or junction are less likely to observe a cyclist who is not occupying the space where oncoming motor vehicles are expected to be observed. This contributes to the SMIDSY(Sorry mate, I didn't see you) phenomenon.

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Oh I see. I thought it was a good idea. –  Ambo100 Aug 9 '11 at 11:00
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Internally-Geared Hub

A setup where, instead of the cogs and derailleur mechanisms are on the outside of the wheel, they're sealed in the rear wheel's hub. As the gears are sealed away from water and road salt, internally-Geared hubs require much less in the way of cleaning than traditional drive-trains. These hubs are popular with commuters or other utility cyclists that will be ride in the snow and rain. They are also popular on folding bikes, as they are suited for bikes taken on crowded trains. When coupled with a single front chainring, IGH drivetrains permit the installation of a full chain guard, which most external gear systems don't allow.

Internal hubs are slightly heavier than comparable external drive-trains.

Hub

Reference:

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Luggage Carrier

(a.k.a. Rack)

A luggage carrier, or rack, is a frame attached to a bicycle to provide space for a pannier or other back to be attached. They are frequently mounted over the rear wheel and are typically bolted to the bicycle and not easily removed.

Heavy-duty rear rack on a touring bike: enter image description here

Reference:

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Gear Inches

One of the several ways to describe gearing; how hard/easy the bike is to pedal. The actual figure is the equivalent diameter of the wheel if you were on a direct pedal cycle like a unicycle or an old fashioned high-wheeler

Easier to pedal (granny-gears) have low gear inches (smaller equivalent wheel). Harder to pedal gears have higher gear inches.

The basic formula is:

GI = (CrT/CogT)*D
WHERE
GI     = Gear Inches
CrT    = Chain Ring Teeth
CogT   = Cog Teeth
D      = Wheel Diameter

For example, a 700c tire is going to have a diameter of roughly 26.3" (depends on the width of the tire). If you have shifted to your smallest front ring of 24 teeth, and your biggest rear cog of 27 teeth then your gear inches are:

GI = (24/27)*26.3 = 23.4"

Note: if you want to take the math a little further - and of course I do since I am a math nut - you can find how far you travel each pedal stroke by remembering that:

Circumference = pi*Diameter

In our example:

Circumference = 3.14*23.4" = 73.5

Note: you can search for Bicycle Gear Calculator and find several pages online that will do the math for you. There will be a lot of variation and calculators use different rounding and make different assumptions about wheel width. Pre-prepared tables are available, calculated for ETRTO 23-622 (700c x 23mm) tyres or in the case of traditional track racers' tables, a "standard" wheel with an assumed 27" overall diameter.

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Tire Lever

aka Tire Iron

A tire lever is a small, narrow lever used to help lift a tire off a rim. Traditionally they were steel, later aluminium alloy and now most commonly they are plastic.

The most important feature of a tire lever is that it does not have any sharp edges that may "pinch" the tube (that is, become wedged between the tube and the tire) causing a small hole or tear in the tube.
Operation of tire levers usually involves either a pair or a triple set of levers. Levers can also be used help get a tire onto a rim when it is a particularly tight fit.

Plastic & Alloy tire levers

More information: http://en.wikipedia.org/wiki/Tire_iron

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Flip-Flop Hub

Most often seen on fixed gear track (velodrome) bikes, a flip flop hub is hub that allows a cog to be attached to each side.

This allows a rider of a fixed gear bike to effectively 'change' gears by taking the rear wheel off, flipping it around and reattaching the wheel.

Track riders will use this to have a smaller (more teeth, fewer gear inches) warmup gear that allows them to spin at a higher cadence and a larger (fewer teeth, more gear inches) cog for racing or high speed efforts.

Variations of flip-flop hubs might offer a freewheel in one direction and a fixed gear in the other, so a cyclist can convert the bike from a single-speed to a fixed gear bike by flipping the rear wheel around.

The unused cog is an additional hazard. Many velodromes require unused cogs to be removed. A collision involving a bike carrying an unused cog at the 2013 North America Harcourt Bicycle Polo Championships led to an amendment of the NAH ruleset to explicitly identify exposed unused cogs as a prohibited hazard. Players are permitted to carry an unused cog if it is covered.

For a fixed-gear road cyclist, a flip-flop hub often is used to allow one side as a fixed gear, and the other side to freewheel. This way, a tired fixie rider can switch to freewheeling (possibly with a different ratio) and get home.

More information: http://en.wikipedia.org/wiki/Flip-flop_hub

alt text

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Bearing

A bearing is an interface between parts that turn and parts that do not. The hubs in the wheels contain bearings, as do the bottom bracket, the head tube, and the pedals.

Wheel bearing -- from Park Tool site

A standard bicycle wheel bearing consists of an axle, a hub, two cones, two locknuts, and a number of steel balls. In both ends of the axle is a concave section known as the "cup" that the balls sit in. The "cone", threaded onto the axle, contacts the balls from the other side, and together the cup and cone retain the balls and serve as the surfaces against which the balls roll.

The locknut secures the cone so that it doesn't thread in or out as the hub turns relative to the (stationary) axle.

The bearings in the bottom bracket and headset are similar except that the cup part is stationary and the axle turns.

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Bottom Bracket

The bottom bracket is the bearing assembly that the cranks attach to.

The bottom bracket shell is the part of the frame holding the bottom bracket.

Generally, bottom brackets are made for a specific size of bottom bracket shell and a specific crank attachment.

Traditional bottom brackets are a piece that goes inside the shell and has the ends of a spindle/axle coming out on each end (which the crankset attaches to), or possibly the cranks somehow attach into it.

There are also external bottom brackets where the bearings are outside the bottom bracket shell, and the cranks have a spindle that runs through to the other side. Typically the bottom bracket in this case is a hollow cylinder with a bearing assembly permanently attached on one side and a way to attach the bearing assembly on the other (once inserted through the shell).

Most recently, there are various new-style ("press-fit", etc) bottom brackets, that are designed like an external bottom bracket, but rely on having a larger bottom bracket shell and fit inside the shell. They still have the axle/spindle as part of the cranks.

Also note that there are eccentric bottom brackets, which are really a bottom bracket that goes inside of an offset bottom bracket shell that fits inside the frame's bottom bracket shell. This allows the bottom bracket to be moved a bit, to tension the chain on a single-speed or fixed-gear bike.

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Track pump (or floor pump)

A large pump that you use by standing on the bottom plate and moving the handle up and down. You can use both hands and your back to pump a high pressure tire quickly and easily. Generally for use at home - or at the track - rather than for carrying on the bike. Some manufacturers make portable track pumps which bolt to the down tube for easier inflation of high pressure tires.

track pump

Features to look for:

  • sturdy construction
  • pressure gauge
  • a head that can be used with both Presta and Schrader valves
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Chain gauge

Measures the stretch of a chain to determine how worn it is and when to replace it.
It's made to fit exactly between two separated links of a standard chain. chain guage

Alternately you can measure the chain with a ruler - standard links are 1inch (25.4mm) long.

Note - the chain doesn't actually stretch, the pins connecting the links wear away making the joints looser. The extra movement reduces efficiency, causes the chain to skip and will wear the rear gear teeth.

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Fender

Mudguard / mudflaps

A must for winter cycling, apart from avoiding the 'skunk stripe' of mud up your back they keep a lot of water and mud from the vital bits of your bike.

fender / mudguard

Can also be DIY'ed from plastic milk cartons.

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1  
A link to a good DIY fender tutorial would be good here. –  naught101 May 13 '12 at 4:29
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Saddle

Also called the seat, the saddle is where the rider sits.

enter image description here

Gel saddle

enter image description here

Leather saddle

enter image description here

Plastic saddle

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