This question and its answers list the names of bike parts and cycling concepts.

Some Rules

  • Make sure you only put one term per answer!
  • Try to include an image if applicable
  • Include sources that contain detailed information
  • Add a link to the index in this question using edit.

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.)

A road bike has the following parts (source):

enter image description here

A mountain bike has the following parts (source): enter image description here

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.


Axle Nuts
BCD (Bolt Circle Diameter)
Bottle Cage / Bottle Holder
Bottom Bracket
Brazed Frame
Cable Pull
Cable Stretcher
Chain Gauge
Chain Guard/Cover
Chain Tool
Chain Tug/Chain Tensioner
Chainstay Length
Clipless Pedals
Coaster Brake (foot brake / pedal brake)
Derailer Hanger/Derailleur Ranger
Disc Hub
Door Zone
Dropper Post
Dunlop Valve
Flip-Flop Hub
Folding Bike
Gear Inches
Hose Clamp aka Jubilee Clip
Hub Skewer
Internally-Geared Hub
Lawyer lips/lawyer tabs
LBS/Local Bike Shop
Luggage Carrier/Rack
Lugged Frame
Master Link
Mountain Bike
Power Meter
Presta Valve/Presta Tube
Pump Peg
REI (Recreational Equipment Inc)
Rim Tape
Schrader Valve/ Schrader Tube
Suspension Fork/Rear Shock
Through/Thru Axle
Tire Clearance
Tire Lever/Tire Iron
Tire Saver
Track Pump/Floor Pump
Triathalon Bars/Triathlon Bars
Welded Frame

  • 6
    one term per answer would be beneficial – dotjoe Aug 26 '10 at 13:51
  • 2
    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
  • 1
    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
  • 2
    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

77 Answers 77



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

example BSO

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 for self-assembly.

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.

  • I softened the language a bit. I agree with you about BSOs, but the situation isn't quite that clear -- and people do occasionally tour on them. (I'll try to dig up a link for that last.) – Neil Fein Sep 17 '10 at 4:18
  • 6
    "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
  • 2
    Suspension - it's not just that it's unnecessary for typical users, but that cheap suspension will add weight and absorb pedalling energy for little or no benefit. (An unpractised rider on pot-holed roads may well benefit from wide tyres though, if not knobbly ones). Also, the typical bike shaped object is heavy, being cheap steel tubes which are both large (to imitate the look of better aluminium frames) and thick-walled (to compensate for cheap steel with cheap welding being weaker). The one illustrated is far from the worst available. – armb Feb 11 '15 at 14:19

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.

  • I've never seen this before in the UK. Interesting. – Ambo100 Aug 8 '11 at 19:09
  • @Amb100: you've never seen a bike lane that ran through the area doors would open into? The "DOOR LANE" thing isn't real, but the configuration of bike lane in door zone is common in the US. – freiheit Aug 8 '11 at 20:29
  • 2
    Oh I see. I thought it was a good idea. – Ambo100 Aug 9 '11 at 11:00
  • Also known as the death zone. As a rider goes slower, they're more likely to be riding closer to the kerb and parked cars. Faster riders tend to move out more and into the traffic lane. – Criggie Dec 6 '15 at 22:48

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.

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

More information: Presta valve (Wikipedia).

Go to Schrader valve.

alt text



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.

The best local bike shops usually have trained staff who have many years of experience in selling, maintaining, and repairing bicycles and have a well-equipped repair workshop. They can special order parts and let you know if a modification you want to make will work -- and how to make it work. As with all things, local bike shops vary in terms of their experience (and attitude) and it pays to shop around to find a LBS that matches your interests and orientation.

Large department or chain stores, on the other hand, often sell BSOs that they assemble using staff who often have little to no background in bicycle mechanics. They cannot repair or maintain the BSOs they sell and your only recourse often is to just return the bicycle if it is still under warranty.

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


Clipless pedals a.k.a. clip-in or step-in pedals

Clipless pedals require a special cleated cycling shoe that locks itself into the pedal's surface. To release a foot/shoe from a clipless pedal, the rider typically twists his/her foot outwards.

The word "clipless" (a rather confusing term) refers to a pedal not having an older style toe clip straps.

LOOK Pedals

LOOK Pedals

LOOK pedals came first and were inspired by ski bindings. LOOK pedals are commonly used on road bikes. A similar (but incompatible) pedal system is Shimano's SPD-SL system.

SPD Pedals

Shimano SPD

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 in mountain biking or similar disciplines, where a rider may need to walk for short distances over some obstacles. Note that Shimano's SPD-SL system is not compatible with SPD.

Cleats used for these pedals have two holes for screws that go into a shoe.



A type of clipless pedal, cleats and compatible shoes used mostly by road race cyclists.

Compared to SPD, this system has bigger cleats which protrude from shoes, making walking in them awkward. Cleats for SPD-SL have three holes.

SpeedPlay Pedals

SpeedPlay Pedals

Design proprietary to Speedplay products. The spring retention and release mechanism in this design is bolted to the shoe, rather than part of the pedal.

Crank Brothers 'Eggbeaters' system

Crank Brothers Eggbeaters

A proprietary design that uses proprietary cleats. Used by Crankbrothers in all their clipless pedals. The most prominent example is the Eggbeaters model range looking very minimalistic.

Toe Clips a.k.a "Rat trap"

pedal with toe clip and strap

Clipless pedals are called so, even though you do clip onto them — because one avoids the need for toe clips and straps.

The word "clipless" (a rather confusing term) refers to a pedal not having these older style toe clip straps.

This answer draws heavily from Clipless pedals (Wikipedia).

  • Aren't TIME pedals kind of major? I see a lot of them (and I own a pair), but it might be some kind of local phenomenon... – dee-see Oct 14 '10 at 23:26
  • @domsterr: Feel free to edit this answer – Dan McClain Oct 15 '10 at 11:27
  • 2
    Added a link to clip+strap pedals, mainly to explain why clipless pedals have clips! – mgb Feb 9 '11 at 5:20
  • Would platform pedals qualify as well, since they are 'clipless' too? – Ehryk Sep 28 '13 at 3:51
  • I don't have the ability to edit (or the knowledge) but I'd encourage a bit of expansion here with shoes/cleats. See: bicycles.stackexchange.com/questions/20700/… – Ryan Mar 12 '14 at 13:13


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.

EDIT by Ivor

To answer a comment below on beginners and cadence...

Cadence is critical to enjoying your cycling and if you become involved in cycle racing, winning. Cadence is something that is learned and once learned you promptly forget about it and move onto getting other things right :)

For a beginner:

  1. Get to know your gears.
    • Drop it into a high gear (big chainring on the front, small cog on the back)
    • Feel how hard it is to push (Pay attention to where you feel the muscles working)
    • Drop it into a low gear (smallest chainring on the front, largest cog on the back)
    • Feel how free your legs spin (Pay attention to how you bounce in the saddle :) If you are bouncing, then you are spinning too much, i.e. your cadence is too high)
    • Find a combination of gears that allow you to spin your pedals without feeling undue pain in your muscles and doesn't make you feel out of breath. (Ignore the speed for the moment)
    • Get to know this "sweet spot", ride around in this gear for a while and adjust your gears to suit your speed so that you balance not being out of breath and over exertion. (Watch out for the bounce in the saddle :) )
  2. The next thing to take into account is how fast you want to go
    • Without a bike computer? - Your feeling of relative speed is good enough
    • With a bike computer? - Set a reasonable target, say 20 km/h
    • Using the gears you have selected for your sweet spot, try to hit your target speed.
    • Once you hit it, can you keep it going? For how long? - Set a reasonable target say 5 mins.
    • When you have finished this, where does it hurt?
    • In your chest? Out of breath big time? - You may have been spinning too much, i.e. your cadence was too high?
    • Muscles in the small of your back, quads, glutes, knees, calves groaning or hurting (not burning, burning isn't as bad as you think) - You may have been spinning too little i.e. your cadence was too low?
  3. There is an ideal cadence proposed by some sports physiologists that is somewhere between 80 to 100 turns of the pedal per minute (rpm)
    • The only way to know your cadence accurately is to have a cadence enabled bike computer and sensor.
    • The other way is to know your gear ratios (Check out BikeCalc.com)
    • For example, You are riding your bike, it has a wheel of size 700c/29 and a tyre that is 23 mm wide, with a front chainring of 34 teeth, a rear cog of 17 and you are pedalling at a speed of 20 km/h. You should then have a cadence of 79 rpm. Simples :) (Get the bike computer ;) )
  4. Get used to spinning your legs in that range of RPM, i.e. 80 to 100 rpm.
    • In all conditions, on any terrain, whatever the occasion.
    • It trains your heart and body to be cardio fit and with a stronger heart comes better stamina and greater strength.
    • Pick up the pace and work to get the legs spinning at the next level of speed.
    • Hard work and worth it.
  5. Go cycling with a group more experienced than you
    • Watch them as they cycle, see all of the different styles and high cadence
    • Listen to the experienced guys as they can advise on many many things.
  6. Enjoy it, you will have earned it :)
  • 9
    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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    I'm not sure that citing Lance Armstrong as an example is really useful, given that he achieved his performances through doping... – mac Apr 26 '14 at 19:53
  • @Ivor my reading of your edit is that it's not clear if bouncing on the saddle is good or not. Can you make that clear please? – andy256 Jan 11 '15 at 4:33
  • 1
    @andy256 I have taken your comments on board and modified the edit. Bouncing is definitely not good. The Quote I used to differentiate the text and have now removed it as the text is my own ramblings on cadence and I am the only one who would claim it :) – Ivor Feb 11 '15 at 10:31

Fixed Gear or Fixed Wheel

AKA: Fixie

A fixed-gear bicycle 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.

Fixed-gear bikes are almost always single-speed (i.e. have only a single gear ratio), but internal-gear hubs without freewheels do exist.

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

Compare with Single Speed.

  • 3
    One should note that typically, horizontal dropouts are required to convert a bike from derailleur to fixed gear, since a pulley cannot be used as a chain tensioner (when you resist to brake, the pulley will be sheared off the bike). Vertical dropouts can be adopted in some cases using something like White Industries' Eccentric Rear Hub or an eccentric bottom bracket or something. – Batman Mar 17 '14 at 6:53

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

  • 1
    I don't think it would hurt to combine this one with its sibling answer – Joe Phillips Sep 6 '10 at 17:51
  • @Joe - Except that it makes linking to one valve or the other more difficult. – Neil Fein Nov 2 '10 at 15:06
  • 3
    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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    What are the advantages/disadvantages of this type of valves? Do they loose more air with time? (compared to presta) Are they heavier? Easier to find pumps for it? – J.A.I.L. Feb 16 '13 at 15:19

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



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.

enter image description here

Often erroneously called a saddlebag because a pannier on a motorcycle or horse is attached to the saddle. On a bicycle, the saddlebag mounts behind the rider from loops at the back of the saddle. The saddle bag goes athwartship – from side to side.

  • How do you pronounce this? pan-near, panny-air, pan-near? – Joe Phillips Sep 6 '10 at 17:54
  • I pronounce it pan-yay, but I'm not sure how to properly say it. – Neil Fein Sep 6 '10 at 18:36
  • 5
    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
  • @freiheit - The link you put in allows for two pronunciations, I updated this entry. – Neil Fein Oct 22 '10 at 14:34
  • 1
    @freiheit: It's an English word that is also a French word. That's like saying "Paris" is an English word that's commonly mistaken for a French word. In English, we pronounce "pannier" as "PAN-yer" and "Paris" as "PAIR-iss" but in French they are pronounced "Pan-YAY" and "Pa-REE." – R. Chung Nov 2 '12 at 19:03


Quick release skewers (sometimes abbreviated QR, sometimes just called skewers) secure bicycle wheels in the dropouts. They have a lever that when opened, enables the wheel to be removed quickly and without additional tools. They use a cam mechanism at the lever end pulling against a threaded nut at the other end. The cam mechanism may be internal or external; the latter type is cheaper to produce and is often lighter, but it produces lower clamping force for the same amount of hand pressure on the QR lever.

a picture of a bicycle front wheel quick release assembly
Quick-release axle (internal cam)

Their invention is frequently attributed to Tullio Campagnolo, but Jan Heine's research shows this may be inaccurate. Heine was unable to determine who invented the QR, as there appears to be no original patent for the QR mechanism.

Tabs called lawyer lips frequently come on fork and/or frame dropouts. They prevent the wheel from dropping out immediately when the QR lever comes open, the nut must be unthreaded several turns as well. These tabs increase the amount of time needed to operate a QR but they can be an important safeguard against improper operation of a QR.

Wheels with disc brakes may be secured by QRs or by thru axles. Disc brakes are said to generate much greater torque than rim brakes; some experts contend that disc brakes can eject wheels from dropouts. Thus, increasingly disc brake bikes and wheels are secured by thru axles rather than QRs.

QRs are sometimes used on seatpost clamps as well, to allow easy adjustment of the saddle height. "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.

  • I know there are some different kinds of quick release. Some have a spring in there to make it easier right? Maybe explain those differences – Joe Phillips Sep 6 '10 at 17:55
  • 3
    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
  • 2
    @Martin - I think the value of a quick release isn't that it's fast so much as that you don't need a wrench to get the wheel off. – Neil Fein Oct 22 '10 at 4:12
  • Well, Tullio Campagnolo's design (which forms the basis of a modern QR skewer) was designed for race conditions, so the speed value exists. I've never heard lawyer lugs, but I have heard lawyer lips. In most cases, however, the primary value is the lack of tools (which does make it relatively faster). – Batman Mar 17 '14 at 6:55
  • and of course in cities like NY you don't want to have a quick release on your wheels because they will get stolen. – Deesbek Nov 28 '16 at 3:09

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


  • Are tri-bars purely aerodynamic or do they adjust your riding position enough to relieve muscles you will use in the run part of a triathlon? – mgb Feb 9 '11 at 5:20
  • Remember Greg Lemond final time trail in the Tour de France 1989. Closest TDF win ever! youtube.com/watch?v=AyvwtOQYQ-E Thank you earobars. – allcaps Apr 14 '14 at 12:08

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. It is still commonly found in Japan and the Netherlands on non-speciality bicycles. The advantage of a Dunlop valve is that it is very easy to manufacture. The main pressure control mechanism is a simple rubber tube called a "plug" or "worm" that can be easily replaced. However, the rubber plugs also quickly degrade and this can be a cause of frustration for users. Recent Dunlop valves in Japan come with mechanical springs rather than plugs.

A pump designed for a Presta valve can be used to fill a tube with a Dunlop valve.

Dunlop Valve

More information: Dunlop valve (Wikipedia).

Go to Presta valve.
Go to Schrader valve.

Also see this answer.

  • 5
    This is the most common valve on everyday usage bicycles in The Netherlands – jilles de wit Oct 19 '10 at 7:40
  • 1
    and possibly here in Poland too – Marcos Mar 8 '12 at 18:22
  • 2
    And Japan, almost all non specialty bikes are Dunlop valves. – RoboKaren Jul 15 '15 at 15:19
  • Very common also in Germany. We distinguish the interior: rubber plug vs. "Blitzventil" (flash valve): Rubber plugs are notoriously hard to pump because there's a lot of pressure lost at the plug, the Blitzventil has a ball valve which works basically without any pressure loss. – cbeleites Jul 22 at 10:19

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

  • Is it possible to use the metal irons with anodized rims without damaging the coating? I bought some cheap ones, and they're ribbed on the face, and a bit sharp on the edge of the face, and when they slip, they dig in to the rim a bit. – naught101 Sep 28 '13 at 0:04
  • and a question here: bicycles.stackexchange.com/questions/17743/… – Móż Sep 28 '13 at 5:01


Attaches the handlebars to the bike, or, more precisely, to the steerer tube. Stems are designed differently for different headset types (i.e. threaded or threadless). They are also sized to suit different diameter handlebars and in the case of threadless setups, different diameter steerer tubes.

Stems of many different lengths and angles are available, so that the rider can position the handlebars where they will be the most comfortable. There are also angle-adjustable stems made, so the rider may change bar positions without removing the handlebars or changing the stem.

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


Chain Tool or Chain Breaker

enter image description here

Used to 'break' a chain by punching out one of the link pins. Needed to shorten a new chain to the correct length or to replace a broken link.

A chain link is placed in the open slot and the handle turned to force a punch pin into the pin of the chain, pushing it out of the other side.

Traditionally the tool needed to be used quite carefully such that the pin would not pushed all the way out, as the same pin was later used to reassemble the chain, using the same tool. Obviously, if a chain is repeatedly "broken" and reassembled this way at the same link the pin and associated holes in the plates will wear and no longer hold well, so care must be taken to not do this.

More recently this strategy has changed somewhat. Shimano now supplies special replacement pins which are equipped with a break-off guide cone on one end, making it easier to reassemble the chain. (Even with this scheme one should still avoid repeatedly "breaking" and reassembling the chain at the same link, though.)

Several other manufacturers now sell what is commonly called a master link (or quick link), which allows a chain to be reassembled without tools.

enter image description here



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.

  • Anyone who has the knowledge, please feel free to expand on this. – Neil Fein Feb 9 '11 at 4:39

Chain Tug

AKA: Chain Tensioner

A device for use on bikes with horizontal dropouts, and normally with a fixed or single speed or hub gear. The chain tug(s) allow the chain tension and rear wheel alignment to be adjusted, and to stop the rear wheel from pulling forward while pedaling. Chain tug 1 Chain tug 2

Some chain tugs are available with derailleur hangers to allow horizontal droput bikes to run derailleur gearing systems.

enter image description here

More information about chain tugs is available in this answer.

Bottom Bracket mounted Chain Tensioners:
Typically seen on downhill styled mountain bikes.

Bottom Bracket Chain Tensioner Bottom Bracket Chain Tensioner on bicycle


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

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. It does allow for different size wheels as well as the gears, but it ignores the effect of different crank lengths.

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
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.


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.

  • Note that tools that work this way are not especially accurate, to work properly both measurement points should be on the same side of the pin they're measuring. – Móż Jun 10 '14 at 2:35


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.

  • 5
    A link to a good DIY fender tutorial would be good here. – naught101 May 13 '12 at 4:29
  • 3
    I'd suggest that a mudflap is different to a mudguard or fender. Mudflap is usually the wide, flexible extension which hangs on the rear end of the mudguard: sjscycles.co.uk/mudguards-mudflaps – James Bradbury Sep 27 '16 at 21:15

Derailleur hanger

The part of the bicycle frame that the rear derailleur screws into. It can be formed as part of the right rear dropout or can be a separate piece. Making the hanger a separate piece allows it to be made from a different alloy than the dropout and to be more precisely machined. Especially on inexpensive bikes, the separate hanger allows the same frame to be used in bikes with or without derailleurs.

On mountain bikes this arrangement is especially required because the derailleur is frequently exposed to hits from ground features and falls, and a hanger softer than the frame will bend first protecting both the frame and the derailleur, like an electrical fuse. This also allows for the hanger to be easily replaced, because frequent bends can lead to a fatigue fracture.

Replaceable derallieur hanger derailleur hanger 2

Often they are built into the frame like this (note that this bike is set up and singlespeed, with a derailleur in place you would never put the axle this far forward in the dropout):

enter image description here

  • why is a separate hanger safer? – naught101 May 12 '12 at 3:01
  • @naught101 because if it bends/breaks you can substitute it. it is actually a breakable part, softer than the frame, so that any force will act on this piece instead of the frame. – bigstones May 12 '12 at 11:02
  • So it's more about safety for the bike than for the rider? – naught101 May 12 '12 at 12:19
  • @naught101 yes. I'm not an english speaker, so feel free to reformulate that part. – bigstones May 12 '12 at 13:32
  • 4
    I'm not sure I agree with the replacement ability not being a primary design point - for off road riding, it seems like this is key, especially on non-steel frames (e.g. aluminum), where the hanger cannot be safely bent back in cases of crashes due to metal fatigue. – Batman Mar 17 '14 at 7:02


The group of bearings and bearing cups that allows the steer tube to turn freely within the head tube. Headsets come in two basic varieties.

Threaded headsets are common on older bikes and inexpensive bikes. They are called "threaded" headsets because the top race is held on with a threaded race and locknut which thread onto a threaded portion of the steerer tube.

Threaded Headset

Threadless headsets are standard on modern mid-level and high-end bicycles. They are called "threadless" headsets because there are no threads on the race or steerer tube nor is there a lock ring. The headset is held together by pressure created by a bolt through the top cap which threads into a star nut inside the steerer tube.

Threadless Headset

Images courtesy of Sheldon Brown.



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.



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

enter image description here

Gel saddle

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Leather saddle

enter image description here

Plastic saddle


Disc Hub

Disc hubs come in two varieties: 6-bolt ISO and Shimano's proprietary Centerlock spline. Converters exist to allow a Centerlock hub to accept a six-bolt disc rotor.

6-bolt ISO:

ISO disc hub

Shimano Centerlock: (Note, centerlock hubs ship with a rubber cover over the centerlock splines). Centerlock disc hub

  • Most Rohloff hubs are also "disk hubs", and come with a proprietary 4 hole mount. No adapter is possible, the reason they do this is because they need a bigger hole than the other mounts allow. – Móż Jan 14 '17 at 6:09

Hub Skewer

A replaceable part of a hub that attaches the hub/wheel assembly to the fork or frame. Some are equipped with a quick-release mechanism that allow removing the wheel without tools, facilitating changing a tire, putting a bike in the back seat of a car, etc. Unfortunately, the trade-off for easy wheel removal is that it's easier for thieves to remove a quick-release wheel.

enter image description here



A combined brake and shift lever. Also referred to as integrated shifters.





A groupset or gruppo (from the Italian for "group") generally refers to all of the components that make up a bicycle excluding the bicycle frame, forks, stem, wheels, tires, and rider contact points, such as the saddle and handlebars.

These parts typically include the following:

  • gear levers / shifters and brake levers or integrated brake levers/shifters
  • front and rear brakes (including calipers/pads or rotors/disks/pads)
  • front and rear derailleurs
  • bottom bracket
  • crankset
  • chain
  • freewheel or cassette

With the following forming part of some groupsets:

  • headset
  • assorted cables and cable housings

SRAM Red Groupset

  • 1
    Is "drivetrain" a synonym of "groupset?" I've heard the two words used almost interchangeably in many contexts. – Jules Sep 23 '15 at 16:02
  • @Jules In motorized vehicles, drivetrain is the set of components that deliver power from the engine to the wheels (excludes the motor). On bikes, I believe that people usually mean the crank, chain, and rear derailleur. It may include the cassette. In principle, the pedals connect the cranks to your legs, so maybe they should be included. I don't think this would fit with common usage (but I could be wrong). – Weiwen Ng Sep 25 at 20:46

protected by Gary.Ray Sep 5 '14 at 13:36

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