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.

  • 7
    One term per answer please - would be beneficial.
    – dotjoe
    Aug 26 '10 at 13:51
  • 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) Aug 26 '10 at 17:12
  • 7
    @MarkIngram: useful things that aren't actually questions are what community wikis are for.
    – freiheit
    Sep 12 '10 at 17:47
  • 2
    This page could use some more love. Maybe if people keep linking to individual terms here, more people will know about this page. Jun 27 '11 at 2:39

89 Answers 89


Bicycle-Shaped Object (BSO)

A derogatory term for a very cheaply produced bike with very low quality components. The components can be hard to maintain due to poor tolerances. BSOs are often sold at non-specialty retail stores.

The etymology of the term is uncertain. It appears in use in some parts of the English-speaking world. It may originate in the UK, as discussed at the link. Other languages may use terms equivalent to supermarket bike or department store bike. These terms are likely to be understood in English as well.

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.

Purchasers of lower-end bicycles tend to be less experienced cyclists who focus on price. 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. For cyclists who are riding on city streets or smooth trails, these features are unnecessary. Including these features reduces the budget available for better components elsewhere.

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.) 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
  • 3
    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


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/


Presta Valve / Presta Tube

aka Sclaverand valve (SV) or French valve

alt text

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.

Presta valve photo credit

Photo sequence of removing the dust cap then unscrewing the nut so the valve is ready to inflate.

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.
Go to Dunlop valve.



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? Sep 2 '10 at 23:11
  • 5
    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

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. These were inspired by ski bindings.

Before clipless pedals, riders used rigid shoes with flat (also called quill) pedals and toe clip straps, as pictured below. The term "clipless" refers to not needing the toe clips. However, it is confusing because riders "clip in" to the pedals.

pedal with toe clip and strap

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.

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 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

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" or "Auto valve" (AV)

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.
Go to Dunlop valve.

  • 2
    I don't think it would hurt to combine this one with its sibling answer Sep 6 '10 at 17:51
  • @Joe - Except that it makes linking to one valve or the other more difficult. 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. Mar 3 '11 at 17:24
  • 1
    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


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. Panniers are most commonly carried on the rear, 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.

Bikes that do not have rack mounts can often accept bags that strap under the handlebars, under the top tube, and behind the seatpost. Gravel bikes often do not have rack mounts, and these alternative bags are used instead. Potentially, these may affect a bike's handling more than a rack and panniers would, because the loads are carried higher on the bike.

  • How do you pronounce this? pan-near, panny-air, pan-near? Sep 6 '10 at 17:54
  • I pronounce it pan-yay, but I'm not sure how to properly say it. 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. Oct 22 '10 at 14:34
  • 2
    @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

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



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 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. 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 handlebars are used extensively on triathlon, time trial, and track bikes, and sometimes in long-distance racing or riding on the road. The position on the extensions reduces the rider's frontal area considerably.

The picture below shows a full aerodynamic bar setup used on a dedicated bike. Shifters are mounted on the extensions, and brake levers on the base bar. One can also buy clip-on bars for standard road bikes. This type of bar would also be used in draft-legal triathlon races.

They are illegal in mass start road races because the aerodynanmic position has the rider's hands away from brakes, and the narrower arm stance makes the rider slightly more unstable on the bike. These factors reduce control.

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
  • @mgb It might be that triathlon bikes in general are designed for a more forward position (steeper seat angle). This is thought to make you use your hamstrings more, whereas you may need your quads for the run. I'm not sure if that contention is backed up by research! forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/…
    – Weiwen Ng
    Nov 12 '19 at 19:19

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 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. Jul 22 '19 at 10:19
  • This post is missing the newer version of the valve and those are much easier to use than the old ones used to be.
    – Willeke
    Nov 21 at 15:41

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 play a key role in setting your riding position. You can adjust the reach to the handlebars by changing the stem's length. Separately, you can move the stem vertically to change your riding position. Stems for road bikes typically come in lengths ranging from 80 to 140mm. Mountain bikes have moved to significantly shorter stems than this. If you need a stem much shorter than 80mm on a road bike, that is a sign the bike doesn't fit you. All else equal, a shorter stem will make for quicker handling. If you are buying a new bike and you know you need a different stem length, the bike store should be willing to trade your stem for something they have in stock.

Another characteristic of stems is their angle. Threadless stems commonly come in angles around -10 degrees, sometimes more. You can flip a threadless stem so that it increases the height of the bar. There are also angle-adjustable stems made, so the rider may change bar positions without removing the handlebars or changing the stem, although their length typically can't be adjusted. An adjustable stem is shown below.

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

The picture below shows several threadless stems of various lengths. All have spacers under the stem. New bikes come with the steerer tube uncut and a number of spacers, up to 40mm (or more). It is common to cut off the excess steerer tube above the stem after you finalize your position. However, you can leave some spacers above the stem, as in the top right picture. In fact, it is advisable to, in case your position changes or you sell the bike.


The picture below shows some threaded stems (also called quill stems). They are shaped like a number 7. The expanding wedge on the bottom of the stem secures the stem inside the steerer tube, and it is activated by the binder bolt on the top of the stem. The stem threads into the steerer tube. Threaded stems have some inherent vertical adjustment available, although be cautious of the maximum and minimum insertion marks.

It is common for threaded stems not to have a removable faceplate, whereas this is rare for threadless stems.


This folding bike effectively has a stem of nearly zero length.



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 that enables the axle to rotate inside some fixed part. The axle rolls on the bearings. For example, consider your hubs, pedals, the cranks, and your front fork. Sheldon Brown has a longer discussion on bearings. Most bearings are steel balls.

Preload is important term related to bearings. For your hubs, preload is how much the hub is getting squeezed in from the side, ignoring the quick release skewer. All cup and cone hubs have inherent preload adjustment, but not all cartridge bearing hubs or other devices do. Too much preload will make the bearings grind and wear out. Too little preload can leave play in the hub (i.e. side to side movement when the quick release skewer is clamped) or other device (e.g. crankset, headset will rock back and forth).

Cup and cone bearings

Wheel bearing -- from Park Tool site

This type of bearing, pictured above, has the balls rotating between the cup and the cone. The locknut tightens the assembly together, and can be loosened with a standard sized wrench.

Cup and cone bearings require periodic service. Service involves cleaning out the old grease, which may have had some dirt mixed in with it, and adding fresh grease. If the balls are worn, you can measure their size with a caliper and buy replacements. Manufacturers may make the cones available as replacement parts as well. The cups may or may not be replaceable.

Cup and cone bearings are more traditional and are frequently present on older equipment, but some companies persist in making high-quality cup and cone bearings (notably Shimano and Campagnolo).

Cup and cone hubs all require preload adjustment. Best practice is to tighten the locknuts so that there is barely perceptible play when the hub is off the bike, and zero play when the quick release or thru axle is tightened.

Cartridge bearings

Most manufacturers have moved to cartridge bearings. Here, the entire system, comprising the steel or ceramic balls, the seals, and the inner and outer races (roughly equivalent to the cone and the cup respectively) are manufactured as a unit. Sometimes they are called sealed bearings, and most of the bearings in bicycles have rubber seals, but this is potentially a misnomer. Bicycle bearings might be unshielded at one end, and cup and cone bearings can have seals built in.

enter image description here

To replace these, you will need a bearing extractor to pull or push the bearing out. The bearings themselves are available commercially. All cartridge bearings have a designation. The numeric part of the designation will specify an inner and outer diameter plus a depth. The bearing code is usually printed on the rubber seal. The numeric part of the code identifies the dimensions. There may be alphabetical suffixes providing further information, e.g. about the sealing arrangement. Do note that bearings with less-protective metal shields exist, as well as unshielded bearings. Those should generally be avoided in bicycle applications.

Most cartridge bearings are designed not to be serviced. They are replaced entirely. In principle, it may be possible to carefully remove the seals with a penknife or similar implement, then clean out the grease and add new grease. Some higher-end manufacturers (e.g. Chris King, Kogel) design their bearings to be serviced periodically, but they may also supply replacement seals if you damage the original ones during removal.

Many cartridge bearing hubs do not have a preload adjustment mechanism, so there is no need to worry about preload. However, some do. SRAM cranks require you to use a collar to preload the system. For Shimano cranks, you just tighten the crank cap to finger tightness, then tighten the pinch bolts. A similar process applies to headsets.


Many factors may influence the durability of the bearing. If you ride in wet conditions, this will reduce durability. If you pressure wash your bike, take care not to point the hose straight at the bearings (in your hubs, bottom bracket, rear suspension pivot). Some bearings are more tightly sealed than others, but the tradeoff is a small increase in friction.

In a press fit bottom bracket, if the bottom bracket seats are not parallel to each other or if one is out of round, that can damage the BB over time. If a piece of equipment was designed with bearings that are too small to take the loads applied to it, that would also impact bearing life. Last, the material quality of bearings and the races they run on has an impact.

Miscellaneous Ceramic bearings are sometimes offered as an upgrade on high-end bikes. They have marginally lower rolling resistance than high-quality steel ball bearings. In many industrial applications, ceramic bearings are thought to be more durable, but this may or may not transfer to bicycling applications. In particular, ceramic bearings are extremely hard, and they must be paired with a high-quality steel race, or else they can damage the race when the bike goes over bumps. This would argue for avoiding cheap ceramic bearings.

Bushings (link to Wikipedia) are another form of bearing. These involve a sleeve rotating over the axle. Bushings are often used in rear derailer jockey wheels and in mountain bike suspension.

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

Derailleur hanger

The part of the bicycle frame that the rear derailleur bolts into. As in the pictures below, most derailleur hangers are separate pieces of metal, often aluminum, that bolt onto the dropout. These are called replaceable derailleur hangers.

Replaceable derailleur hanger derailleur hanger 2

Derailleur hangers frequently bend slightly if a bike is dropped or crashes, which is especially common off road. This can compromise shifting. The key advantage of a derailleur hanger that is softer than the frame is that in a crash, it will bend and break before the derailleur or the frame. The hanger can then be replaced. Replaceable hangers are proprietary to each frame and tend not to be interchangeable. Manufacturers will usually stock them as replacement parts. The US company Wheels Manufacturing makes a wide variety of replacement hangers also.

Non-replaceable derailleur hangers are part of the dropout, as in the picture below. (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)

derailleur hanger integrated in the frame

These hangers are present on some steel and titanium bikes. If the derailleur hanger is bent, it will need to be cold set (i.e. bent) back into alignment. Tool manufacturers make derailleur alignment gauges for this purpose. Steel and titanium hangers can be bent repeatedly. If a non-replaceable derailleur hanger breaks, an experienced welder (preferably a frame builder) will need to replace it.

  • 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.


Chain Tug

AKA: Chain Tensioner

On most bikes, the rear derailleur keeps the chain in tension. On fixed gear, single speed, or hub geared bikes, a chain tensioner is required to keep the chain in tension. Without this mechanism, the chain may fall off, or the rear wheel may pull 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

  • Small correction: A chain tug is only used and required with those horizontal, rear-facing drop outs. And that is not popular everywhere. In other countries, single speed and IGH bikes use forward facing dropouts where the axle is held in place by friction (requires proper tightening of the axle nuts). This makes it extremely easy to take out the rear wheel, or to replace it (no need to open the chain lock, you can simply pick the chain off the sprocket after taking out the wheel), and is surprisingly robust if tightened properly. Nov 11 at 8:02

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 and Tire Diameter

For example, a 700c tire is going to have a diameter of roughly 26.3" (depending on the width of the tire). Note that larger tires on the same wheel will give higher gearing (i.e. more gear inches), even though the gearing (i.e. chainring and cog) are the same. 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. Synonyms include: chain wear gauge, chain checker 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

Bottom Bracket

The bottom bracket (BB) holds the cranks, and it the contains bearings that let the axle rotate. BBs may incorporate the axle the axle that the cranks attach to, or the axle may be bonded to the cranks. The bottom bracket shell is the part of the frame holding the bottom bracket, and it has a. Note that road and mountain bikes have different BB shell widths, so you can't interchange their cranksets.

Bottom brackets with cup and cone bearings will require periodic cleaning and regreasing. BBs with cartridge bearings are replaced entirely when the bearings are worn, although some are designed for periodic service. Your manufacturer instructions will state this.

Threaded bottom brackets

Traditional bottom brackets screw into the bottom bracket shell. BB axles/spindles for threaded bottom brackets can be square tapered (in two standards, the more common Japanese International Standard and ISO, used by Campagnolo and a minority of manufacturers) or oversized (Shimano Hollowtech or International Spline Interface Standard, or ISIS). Generally, the oversized spindles were stiffer due to being larger, but had smaller bearings and may have had poorer bearing life. The crankarms were then fixed on to each side of the axle with retaining bolts. In older threaded systems, the bottom bracket contains the crank axle.

External bottom bracket cups came into play in the early 2000s. Here, the bottom bracket assembly contains only the bearings, and the crank axle is attached to one or both crankarms. The axle goes through the bottom bracket.

Among bikes with threaded BBs, the majority conform to the English standard. Many Italian frames used the Italian standard. There is a modern oversized threaded standard called T47. This has an internal diameter of 46mm (compared to the 35mm diameter of the British standard).

On most threaded BBs, the bearings are not accessible for maintenance. Users will frequently discard them when they are worn out. It is possible for users to damage the threads when installing BBs, e.g. by forcing a BB in at an angle. A bike store can chase the threads to attempt to restore them. If the threads are beyond repair, it is possible to ream and re-tap a British threaded BB to the Italian BB standard, because the latter has a slightly larger diameter (36mm vs 35mm for BSA). This will have to be done cautiously, and not all shops will have the necessary tools. Also, Italian BBs are right hand threaded on both sides. The drive-side cup may unscrew as you pedal, but this can be fixed with adhesive (e.g. Loctite).

Press-fit bottom brackets

Later, various press-fit bottom bracket standards were developed where the frame contains a molded seat for bearing cups. It is not possible to cut threads into carbon fiber. The alternative to press fit involves bonding a threaded alloy sleeve into the frame, and press fit is simpler and lighter.

There are numerous standards for press-fit bottom brackets. Cups for one standard are not interchangeable with a different standard. However, for each press fit BB standard, manufacturers will make cups to accept most or all cranksets on the market. Examples of open standards include BB86 and Press Fit 30. Some larger bike manufacturers have BB standards proprietary to their own frames, such as Cervelo (BBRight), Cannondale (BB30 and descendants), and Trek (BB90, although they appear to be transitioning to T47 as of 2021).


Most BBs use sealed cartridge bearings. The whole BB is replaced when the bearings are worn, as discussed in the article on bearings. Some BBs with cartridge bearings may be serviceable, which usually involves removing the seals, using a degreaser or WD40 to clean the bearings, and then regreasing, but most of the time the bearings themselves aren't physically accessible. This also applies to older cup and cone BBs. Riders should avoid spraying water directly at the BB from the side of the bike when cleaning it.

Selecting a Bottom Bracket

For press-fit systems and modern cranks, you need to know both the BB shell type and axle type (e.g. Shimano, SRAM DUB, Campagnolo, other). For square taper systems, you need to know the length of the taper (e.g. 108mm) and the type (JIS or ISO).

Current generation cranks can have axles ranging from 24mm (Shimano) to 30mm (so-called BB30 cranks). Many cranks can mount to most BB shell types. Manufacturers even make BBs for 30mm spindles in BSA and Italian shells. However, Trek used their own BB90 standard which was incompatible with many 30mm spindles, although Trek appears to be phasing BB90 out as of 2021. There may be a few more cases of incompatible hardware.

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.

  • 1
    Note: may be at the front or back of the bike rather than the bottom. And is not a bracket.
    – Мסž
    Apr 20 '11 at 4:38
  • I've recently been made aware of sealed, unsealed, and external BBs. Can here anyone expand on the difference between them? Jul 31 '11 at 16:00
  • This actually describes the bottom bracket shell. The bottom bracket is the bearing assembly and is usually removable...
    – freiheit
    Oct 31 '12 at 17:25
  • @freiheit - fixed, feel free to edit further. Nov 1 '12 at 19:52
  • Ok, I edited the heck out of it. I didn't mention sealed/unsealed, but I did explain external BBs and tried to explain the new external-style-but-actually-go-inside-a-larger-shell-BB style that I can't figure out the standard name for (it's called "press-fit" on one of my bikes, but the same thing also can screw in...)
    – freiheit
    Nov 2 '12 at 23:34

Cable Stretcher

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


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

  • Can you explain what you would use it for? I'm betting most people don't install their own brake cables. Sep 6 '10 at 17:53
  • 1
    I have never had problems installing brake cables with a standard set of pliers.
    – Ian
    Sep 17 '10 at 9:22
  • @Ian - I've frayed cables by doing this. Perhaps I need practice! Feb 9 '11 at 10:29
  • 3
    @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
  • 1
    @Ian superglue also works! May 16 '16 at 8:01

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
  • Also useful for Dunlop valves (which are very much still used by bicycle users in some countries.)
    – Willeke
    Nov 21 at 15:44


Mudguard / mudflaps

A must for winter cycling. As the wheel rotates, it will spray water and dirt up a rider's back and onto various parts of the frame. Fenders block this spray. They are often recommended for riding in wet weather. Mudguards are flaps attached at the ends of a fender.

fender / mudguard

Commercial fenders can be made from metal or plastic. They can also be DIY'ed from plastic milk cartons. Typically, fenders require the frame and fork to have fender mounts. However, some fenders, like the ones depicted, can attach on to the frame and fork directly. This mounting is less secure, and such fenders do not cover as much of the wheel.

If an object like a stick gets jammed between the tire and fender, it can cause the fender to break off. The frame may be damaged as well. If there is not much clearance between the fender and tire, this may be an argument for using fenders made for race bikes. These fenders may just bolt to the seat stay and down tube, and will offer partial protection from dirt and water.

  • 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 Sep 27 '16 at 21:15
  • 1
    It should be added that some road-riding clubs see mudguards as mandatory for wet and/or winter rides - the reason being that they stop the rider behind you getting a mouth full of whatever is currently on the road.
    – David Kemp
    Oct 22 '19 at 11:54


A groupset or gruppo (from the Italian for "group") refers to the components involved in shifting gears, braking, and transmitting power from the rider's legs to the rear wheel. Relatedly, sometimes people say "drivetrain." In bicycles, the term is not formally defined, but it definitely includes the chain, chainrings, and cassette.

Groupsets typically include:

  • integrated brake levers/shifters (on older bikes, brake levers and down-tube or bar-end shifters)
  • front and rear brakes (including calipers/pads or rotors/disks/pads)
  • rear derailleur
  • front derailleur (unless the bike has a 1x drivetrain)
  • bottom bracket
  • crankset or chainset
  • chain
  • cassette (freewheel on older bikes)
  • cables and housings or hydraulic hoses as appropriate (for electronic groupsets, control wires and batteries)

In the past, groupsets have included some or all of the following components or groupset manufacturers have offered these items, but these are not considered parts of the groupset.

  • headset
  • hubs and usually quick release skewers
  • stem and seatpost may have been included, or may have been optional purchases
  • pedals are typically optional purchases

SRAM Red Groupset

Shimano, SRAM, and Campagnolo account for the vast majority of road bike groupsets. SRAM had entered the road bike market in 1988, then exited, then re-entered in 2004. Shimano and SRAM are the majority of the mountain bike groupset market. Campagnolo briefly produced one mountain bike groupset before exiting that market. At the time of writing, Full Speed Ahead and Rotor have produced groupsets as well, but these have yet to achieve widespread take up.

Groupsets are offered at a range of price points. Each of the 3 major manufacturers makes one version for professional road (e.g. Campagnolo Super Record) or mountain bike racing (e.g. SRAM XX1). They also offer various lower level groupsets for consumers. Generally, the high-performance consumer groupsets (e.g. Shimano 105 and Ultegra) will have less exotic material (i.e. less titanium and carbon fiber) used in manufacture and will be heavier, but will usually offer very similar performance on other characteristics (e.g. durability, shift quality). Groupset manufacturers generally offer electronic shifting versions of their top two groupsets.

The original equipment manufacturer (OEM) market is dominated by Shimano and SRAM (i.e. most complete bicycles come with Shimano or SRAM components). For the most part, shifters and derailleurs are not compatible between brands, and complete bicycles will not mix these components. However, some complete bicycles will substitute cranksets and/or brakes from third party manufacturers for cost or performance reasons.

  • 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 '19 at 20:46


The part of the bike you hold with your hands. When you turn the handlebars, the front wheel turns with them. The stem clamps onto the handlebar and onto your fork steerer.

Broadly speaking, there are flat handlebars as found on mountain bikes and hybrid bikes, and drop handlebars which have bar ends that are curved below the flat portion. Flat handlebars offer better control in rough terrain. Drop handlebars are used on road and gravel bikes, and they offer a wide variety of hand positions. This question discusses in some detail the various positions you can take on drop bars.

If you are replacing handlebars, they are mainly characterized by their width. For drop bars, one guideline for road bikes is that the bars should approximately equal your shoulder width. Gravel cyclists frequently opt for relatively wide bars, and they also opt for flared bars where the drops are wider than the hoods. Professional road racers are increasingly opting for narrow bars. Mountain bike handlebars are significantly wider than road bars, and are frequently trimmed to the desired length after some experimentation.

This question discusses different subtypes of each of the two classes of handlebars.

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

enter image description here

Leather saddle

enter image description here

Plastic saddle


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

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