Anatomy Of A Bicycle
There are many different varieties of saddles. Racing saddles are narrower, have less padding, weigh less and are usually made with higher-end materials like carbon fiber, titanium and exotic alloys. Comfort saddles are wider and heavier, with much more padding for comfort. There are different saddles for men and women. Men's saddles are usually narrower and longer than women's saddles, which are wider and shorter.
This connects the saddle to the frame. Seatposts can be made from aluminum, carbon fiber, titanium or steel, with aluminum being the most common. Seatpost size is determined by measuring the diameter of the post. Most seatposts have the size etched on. Some common sizes for road and comfort bikes are 26.8mm, 27.2mm and 31.6mm. Common mountain bike sizes are 27.2mm, 30.9mm, and 31.6mm.
There are four different types of brakes: Caliper (road), Cantilever, Linear Pull or V-Brakes, and Disc. Caliper brakes are found most often on road bikes and mount with a single bolt located in the center of the brake. Cantilever brakes are most often found on mountain bikes, hybrids and Cyclocross bikes. Cantilever brakes mount to posts located on the frame and fork. The cable attached to the brake looks like an upside down "Y." Linear side-pull (V-brakes) also mount to posts same bikes as Cantilever brakes. With Linear side-pull brakes the cable goes through a metal tube attached to one brake arm. Disc brakes come in basically two types: hydraulic and mechanical. Disc brakes mounts are located on the frame near the dropouts and near the bottom of the fork leg.
A Wheel is made up of a rim, spokes and a hub. Rims come in basically four different sizes:
o 700c----- Most new road bikes, built after 1990, including Hybrids
o 29”------- Some mountain bikes
o 650c----- Women's specific road bikes and Triathlon bikes
o 27.5”/650B---- Some mountain bikes
o 27"------- Older less expensive road bikes, most made before 1990
o 26"------- Some mountain bikes and some "comfort" bikes
*Tires must be the same size as the rim. 700c rims mean 700c tires, 27" rims mean 27" tires, etc.
The two most common rear hubs are freewheel hubs and cassette hubs. With freewheel hubs the cogset (freewheel) is all one piece and is threaded directly onto the hub. With cassette hubs the cogset (cassette) is separate and slides onto the hub and held in place by a lockring.
Wheels are also distinguished by brake type. Wheels made for standard road calipers, cantilever or linear pull brakes will have a brake track on the outside of the rim. Wheels made for use with disc brakes have no brake track, but will have mounts of disc rotors on the hubs.
Spokes come in a two different styles: straight gauge and double butted. Straight gauge spokes are a single thickness. Double-butted spokes are two thicknesses, thick on the ends and thinner in the middle.
Click here to check out our wheel's buyers guide.
Cassettes are the clusters of gears that attach to the rear hub of the bike. They determine how many speeds your drive train has. Cassettes mount to the freehub body of your rear wheel, and are held in place by splines and a lockring. SHIMANO and SRAM share the same spline pattern and can be used interchangeably on wheels with SHIMANO pattern freehubs. Campagnolo cassettes use a separate standard and require a specific freehub body to mount. Most modern bikes come with either 8, 9, 10, or 11 speed cassettes today, in gear spreads that range from 11-21 all the way up to 12-36, and even 10-42 (mountain bike only).
Used to guide the chain from cog to cog on the rear cassette. Rear derailleurs come in different cage lengths. Long cages rear derailleurs are for bikes with Triple cranksets, mountain bikes, or bikes with cassettes with very large cog sizes. Short cage derailleurs are for bikes with Double cranksets.
Used to guide the chain from chainring to chainring (on the crankset), the front derailleur has a few distinctions: mount type (Braze-on, E-Type or Clamp-on), pull (top or bottom) and swing (top or bottom). Braze-on front derailleurs bolt directly to the frame. Clamp-on front derailleurs have a clamp that goes around the seat tube and tightens with a bolt. The E-type front derailleur mounts to the bottom bracket.
Pull is from what direction the cable comes to the derailleur:
o Top-pull = cable comes from above the derailleur
o Bottom-pull = cable comes from under the derailleur
Swing refers to where the derailleur cage pivots:
o Top-swing = cage pivots above the clamp
o Bottom-swing or traditional = cage pivots below the clamp
A Crankset consists of two crank arms and either two (double) or three (triple) chainrings. The bottom bracket connects the crankset to the frame. Bottom bracket consists of bearings, cups and a spindle. There are several different spindle styles: pressfit bottom brackets, external bearing bottom brackets, square taper bottom brackets, and splined bottom brackets. Pressfit and external bearing bottom brackets are the most common, while square taper and splined are older standards that are still found on some bikes.
There are basically two types of pedals, platform (with or without toe clips) and clipless. Platform pedals do not require a special cycling shoe. Clipless pedals are sold with cleats that mount to the bottom of a cycling shoe. These cleats come in two bolt pattern for most mountain bike shoes, 3 bolt pattern for LOOK, TIME, SHIMNAO SPD-R, and a few others, and 4 bolt pattern for SPEEDPLAY.
This is the set of bearings and cups that connect the frame to the fork and allow you to steer a bike. There are two types of headsets: threaded and threadless. Threaded headsets have two lock nuts threaded directly to the fork used for adjusting. The threadless headsets use a bolt and either a star-fangled nut or compression plug to adjust. The star-fangled nut is used for forks with an alloy steerer tube, while the compression plug is used on forks with carbon steerers..
There are two different types of stems: threaded (quill) and threadless. Threaded stems have a quill that slides into a threaded steerer/headset (see above) and is tightened via a bolt and wedge. Threadless stems clamp directly to the steerer tube and are tightened by one or more bolts. Stems consist of two measurements: length and diameter. The length is measure along the stem, from the center of the quill or steerer clamp to the center of the handlebar clamp. The diameter of the stem refers to the steerer tube of the fork it fits with.
**See Fork for description of steerer tube
The cockpit of the bike, handlebars come in a variety of different styles. Road bikes come with Drop-bars; these bars have a flat sections with two hooked areas that drop below the flat portion of the bar. These bars must be mounted to a road stem. Mountain bikes primarily have one of two bars, either flat bars or riser bars. Flat bars are flat across the bar but sweep back towards the rider. Riser bars sweep back towards the rider as well, except they also rise up from the stem.
Most modern road bikes are equipped with either Shimano STI, SRAM Doubletap, or Campagnolo Ergo levers. These levers integrate shifters and brake levers into one unit. Older bikes are equipped with downtube shifters and separate brake levers. The downtube shifters are mounted the frame located just above the waterbottle. Touring bikes are sometimes equipped with bar end or "Bar Con" shifters. These shifters mount into the ends of the handlebar.
Mountain bikes offer a wider variety of brake and shift lever combinations. They can either be integrated with the brake and shift levers mounted together or separate. The two most common shifters are Shimano and SRAM.
The fork is the part of the bike that holds the front wheel, and pivots to allow you to steer the bike. The fork is made of the parts: the arms, the crown, and the steerer tube. The arms are the two tubes that attach to the wheel, the crown is where they meet in the middle, and the steerer tube is the tube that sticks out from the crown and inserts into the bike frame. Steerers can either be threaded or threadless (see: bottom brackets, headsets sections). There are two types of forks: suspension and rigid. Suspension forks offer travel much like a motorcycle and are found mostly on mountain bikes. Rigid forks have no travel and come in many different materials: Carbon, Aluminum and Chromoly. Forks have three different measurements: steerer diameter, steerer length, and wheel clearance.
-Steerer diameter = outside diameter of the steerer tube
-Steerer length = length of steerer tube from crown to top of steerer tube
The frame is the main part of the bicycle, and usually consists of a double triangle construction—a design that dates back to the late 1800’s and was originally called the safety bicycle. Bicycles frames are made of either steel, aluminum, titanium, or carbon fiber. The bicycle frame itself is composed of several component parts:
- Head tube: the front tube where the fork steerer inserts
- Top tube: the long tube that makes up the “top” of the bike
- Down tube: the long tube that runs at a downward diagonal from the headtube
- Seat tube: the middle tube of the bike, where the seatpost inserts
- Bottom bracket shell: the round shell connecting the downtube and seatube where the cranks are attached
- Seat stays: the two thin, downward angled tubes that connect from near the top tube to the wheel hub
- Chain stays: The horizontal tubes connecting from the bottom bracket shell to the wheel hub
- Drop outs: The (usually) metal piece where the rear wheel skewer attaches, connects the seat stays and chainstays (the part of the fork where the wheel attaches is also called a drop out)
- Derailleur hanger: the hook-shaped metal piece on the driveside dropout where the rear derailleur attaches
- Water bottle bosses: the holes where the water bottles bolt in
- Fender/rack braze ons: the small mounts near the front and rear drop outs where fenders and racks mount (not all bikes have these)
- Front derailleur hanger: Not found on all bikes (some bikes require a clamp-on front derailleur), this is where the front derailleur mounts
- Brake drill outs (road bikes): the holes in the fork and on the bridge between the seat stays where the brakes mount
- Disc tabs (disc brake bikes): the set of tabs one the non-drive side where the disc brake caliper works
- Canti posts (cantilever/v-brake bikes): a set of posts on the fork arms and seat stays