Anatomy of a bike

A bike is an elegant collection of parts, some of which get a bit technical. So you don't get lost in the jargon, here's a quick rundown of the anatomy of your bicycle, with a bit more detail on each part, what purpose it serves, and what some of those more technical terms actually mean. 

Bike Anatomy


Bike saddles

Road saddles

Road bike saddles tend to have less padding and are focused mainly on saving weight. They vary in widths and care meant to fit to your hip bones. Most road bike saddles allow for a more aggressive position on the bike and provide a more aerodynamic position for the rider.

Sports saddles

Sport saddles are designed to fit well with hybrid bikes. Usually they have more padding than a road bike saddle, but not quite as much as a full-on comfort saddle. For the rider trying to ride a long ride and finds road saddles uncomfortable, a slightly more padded sport saddle would be the right choice.

Comfort saddles

Comfort saddles are for the rider looking simply for comfort and nothing further. These saddles tend to have lots of gel or foam padding, and usually weigh more than road or sport saddles. Comfort saddles have the most cushion and are for riders looking for an all-around comfortable ride.


Bottom bracket

The bottom brackets connect the crank-set to the bike frame. There are two types, threaded and press-fit.


Threaded bottom brackets contain bearings that are pressed into aluminum cups which are then threaded into the frame.


Press fit bottom brackets take bearings and press them directly into the frame.



Coaster brakes

Coaster brakes are usually seen exclusively in cruiser or children’s bicycles and operate when a bike rider pedals backwards. Coaster brakes are located on the hub of rear wheel and activated by rotating the pedals in reverse which ignites the brakes.

Rim brakes

Rim brakes are the traditional style brakes found on most bikes and can work very well when setup and used correctly. They do not need constant adjustment and the brake pads, when needed, are reasonable in price (~20.00). Rim brakes become less efficient in wet or dirty conditions but are still the most common brakes seen on the market today.

Disc brakes

These brakes offer reliable stopping power in all conditions. This means you can control how much stopping power you are giving the brake easily. Disc brakes offer assured stopping no matter what gets on your brakes or if they get wet and they last a long time. On the other hand, disc brake pads can become contaminated with oils or grit and lose power. It is important to remember to NOT touch the disc rotors with your hands; the oil on your skin corrupts disc brake pads. The discs can also become bent or warped, but that can be fixed by a bike mechanic. Disc brakes are becoming far more common and are a great option for any rider as they perform reliably in all conditions.

  • Hydraulic disc brakes use either mineral oil or DOT fluid to operate a piston which clamps brake pads down onto a disc, like a car or motorcycle brake. Hydraulic disc brakes do require more maintenance than mechanical disc brakes since you should add new fluid once a year or so, but they modulate better in wet conditions and provide overall better stopping power.
  • Mechanical disc brakes work along the same principles that hydraulic disc brakes do; they use two pads that clamp down onto a disc rotor that is connected to each wheel respectively. The main difference is that instead of a piston being activated by hydraulic fluid, the pads are controlled and actuated by a cable. The main advantage of mechanical disc brakes is less maintenance and easier adjustments. The disadvantage is that although they do provide more reliable braking than standard v-brakes, they do not provide the modulation or braking power that hydraulic brakes do.



The cassette is the stack of gears located on your back wheel. When you shift the derailleur moves the chain up and down the cassette to a different cog. Cassettes come in different tooth ranges to accommodate different terrains. 



The chain-rings are the large rings connected to the crankset which the chain attaches to in order to transfer energy, driven by the pedal and cranks, to the wheel. Chain rings can range in size, going anywhere from 20 – 60 teeth depending on their desired range.



The crankset is a component on the bicycle frame that is part of the drive-train. It takes the power generated from the pedals and uses it to drive the chain which rotates the rear wheel.

Triple crankset

The triple crankset has 3 chain-rings; and usually has 8 or 9-speeds to offer the rider 24 - 27 gears. This allows the rider to have a wide range of gears.

Double crankset

This crankset has 2 chainrings and a 10, 11, or 12-speed cassette to offer the rider 20 - 24 gears. It weighs less than a triple, and still offers a large gear range. The double crankset also helps reduce drag on the derailleur that can sometimes be found with a triple crankset.

1x crankset

The 1x drivetrain is a fast-growing sensation in cycling. With only 1 chainring on the front of the drivetrain with no derailleur, shifting becomes simpler and you shed weight off your bike. 1x drivetrains are already becoming standard on gravel, cyclocross, and mountain bikes and are even being adapted for road bike use.




Rear derailleur

Rear derailleurs are the part on the back of the bike frame that move the chain up and down the cassette when the rider wants to change gears. Rear derailleurs can either be cable actuated (mechanical), electronic, or hydraulic in nature, and range from 3-13 speeds.

Front derailleur

Front derailleurs shift the chain in the front section of the drive-train from the smaller chain-rings to the larger, or vice versa. Front derailleurs are either cable activated (mechanical) or electronic in nature. Front derailleurs come in either 2 or 3 speed variants depending on whether the bike has a 2x or 3x drive-train.



The fork is the part of the bike that holds the front wheel and connects to the handlebars to control steering.

Rigid fork

Rigid forks are most common on road, urban, cruiser, and hybrid style bikes. They can be made of steel, titanium, aluminum or carbon fiber. Rigid forks have good power transfer and make the bike feel stiffer and more responsive overall.

Suspension fork

Suspension forks are found most commonly on mountain bikes and some hybrid bikes. They use coil springs or air pistons to modulate a certain amount of travel; i.e. the upper stanchions of the fork can travel into the hollow lowers of the fork.



Down tube

The downtube is the largest piece of tubing on the frame; it connects the headtube (where the handlebars sit) to the bottom bracket shell and seat-tube (near the crankset). 

Top tube

The top tube is the highest piece of tubing on the frame that runs from the headtube near the stem to the top of the seat tube.

Head tube

The head tube is the tube at the front of the bike where the down tube and top tube intersect. It holds the headset bearings that allow the steerer tube to move.

Seat post collar

The seat post collar is a piece of metal, usually aluminum, which wraps around the outside of the top of the seat tube and torques down to hold the seat post in place.

Bottom bracket shell

The bottom bracket shell is the connecting point for the seat tube, down tube, and both chain stays. It houses the bottom bracket and crankset.

  • Seat Stays: The seat stays are two diagonal pieces of the frame that run down from the seat tube to the back of the frame. The seat stays provide rigidity to the frame and some compliance for rougher roads/terrain.
  • Chain Stays: The chain stays connect the bottom bracket shell to the rear dropouts of the frame. The shorter the chain stays, the more responsive the bike will feel. The longer the chain stays the more stable the bike will feel.
  • Drop Outs: Drop outs are the slots on the fork and the chain stays where the wheels fit into the frame.
  • Derailleur Hanger: The derailleur hanger is a piece that connects to or is a part of the drive side chain stay. It allows the rear derailleur to connect to the frame and will shear off if the bike is put under major stress, instead of the chain stay breaking and ruining the bike.
  • Fender/Rack Braze Ons: Some frames will have mounting points on the fork and/or on the rear seat stays for mounting fenders or bike racks on.
  • Disc Tabs: Disc brake frames will have mounting posts on the non-drive side chain stay and on the non-drive side of the fork. These are the areas where you would mount disc brakes.
  • Canti Posts: Older cyclocross or mountain bikes, or new canti-specific frames might have posts on the rear seat stays and the fork for cantilever brakes, which are like V-brakes but with larger tire clearance and better braking modulation.

Frame Materials


A steel frame is sturdy and absorbs some vibrations when riding but is the heaviest of the three.


Aluminum frames are the most popular, they are both light and stiff, and are widely used across many bike styles. The trade-off is that you feel a bit more vibration from the terrain.

Carbon Fiber

A carbon frame is the lightest of the four materials and is also the strongest. Carbon fiber is a weave of carbon that is held together with a special glue. Carbon fiber is extremely durable and light but does tend to be more expensive than aluminum or steel framed bikes.


Titanium is a frame material usually used by custom frame makers. It combines the strength and durability of aluminum with the lightweight construction found with Carbon Fiber. Titanium frames usually tend to be the most expensive.




This type of handlebar creates a more aerodynamic shape with the rider’s body. This means you will be able to go faster since the transfer of energy forward becomes more efficient. There are also more places to put your hands creating numerous riding positions. One thing to consider with drop-bars is the position of your back if you are a less flexible rider, stretching off the bike will help make this easier.


Flat-bar handlebars create an upright riding position. This allows a rider greater ability to see the road ahead more clearly and have less pressure on their lower back. 



The headset is the part of the bike that allows the steerer tube and fork to turn smoothly in the headtube of the frame. The headset consists of 2 cups that are packed with ball bearings. Keeping the headset tightened correctly and packed with grease are very important maintenance points to keep your bike running as smoothly as possible.



Platform pedals

These pedals are the most commonly recognized pedals across categories. Their flat surface provides an even surface for your foot to rest on. Platform pedals can be used with a variety of shoes and are the easiest to remove your foot from. This type of pedal is ideal for someone who is just beginning or is uncomfortable with their foot being restrained.

Caged pedals

Another type of pedal commonly seen on road bikes is a pedal with a toe cage that can be adjusted to your feet. Cages encase the front of your foot to allow you to complete your pedal stroke with an upward pull. The ability to both push and pull on your pedal stroke increases the overall efficiency of each stroke. For cyclists looking to migrate toward clipless pedals, this is a great, cost-efficient, way to get used to the feeling of having to remove your foot from the pedal when you stop.

Clipless pedals

Road cyclists may be most known for these pedals where you actually “clip in”. While there are many kinds of clipless pedals, this form of pedal provides the most efficiency to the power of each pedal stroke. This pedal works by connecting a special bike shoe that has a cleat on the bottom directly into the clips of the clipless pedal. Clipless pedals do take some work to master, but after a while, it becomes second nature and your ride will be more efficient because of it. 


Seat posts

Seat posts are a very important part of a bike; they connect the seat to the bike frame allowing the rider to sit at a comfortable height.

Seat posts come in many different sizes, but most commonly come in either 27.2, 30.9, or 31.6mm diameter.

Seat posts are made from a large variety of materials including steel, aluminum, titanium and carbon fiber. There are also seat-posts with built-in vibration damping for rougher rides or off-road terrain.


Shifters and brake levers

STI/Double Tap shifters

STI or Double Tap shifters are what most would consider to be traditional road bike style shifters. They use a shifter/brake combo that goes onto the downcurve of a road bike handlebar. Both SRAM and Shimano make lines of road bike shifters that are commonly seen on dedicated road bikes, gravel bikes and cyclocross bikes.

Flat bar shifters (trigger/grip)

Flat bar shifters are most commonly seen on mountain bikes, hybrids and cruiser bikes. They come in two different variations, grip shifters and trigger shifters. Grip shifters use a twisting motion to pull or release the cables to change gears. Trigger shifters use buttons/triggers to move between different gears.

Friction shifters

Friction shifters are far less common than they originally were, although they are spotted occasionally. Friction shifters are usually mounted on the downtube of a bike and use friction to shift between gears; riders must feel the gears and adjust the shifters accordingly.




The stem is the part of the bike that connects your handlebars to your steer tube. Stems come in many different lengths and have different angles that can help with your bike fit to make your ride as comfortable as possible.



Bikes that only have front suspension are often referred to as “hardtails”. This means that the frame is rigid, and there is a suspension fork on the front of the bike which will hold the front wheel on the ground and provide some relief from the roughness of the road. 


Full suspension mountain bikes are bikes that have suspension built into the rear of the frame in addition to a suspension fork in the front of the bike. The advantages of full suspension are that more of the roughness of trails is taken out and  the rear suspension helps to keep the back wheel planted when going over rough terrain, giving the rider more control.


Some bikes come with neither suspension in the rear or the front. These bikes are considered fully “rigid”, meaning they have no suspension. The advantage of a rigid bike is that no power is lost during suspension modulation and so power transfer is much more efficient.


Tires and sizes

Road bike tires and sizes

You will often see road bike tires labeled something like 700×25. The first number, in this case 700, indicates the diameter of the tire in millimeters and is standard in the category. The second number, 25, shows the width of the actual rubber tire in millimeters and is more likely to vary across individual bikes in the category.

  • 25mm: This tire width offers the smoothest ride, most comfort, stability and speed for road tires. This tire size is great for any road rider looking for a more compliant ride and for those racers who want to gain comfort and speed.
  • 23mm: This tire width is being seen less and less on road bikes today. These tires still offer a degree of stability but are also lightweight and more aerodynamic than the wider range of tire sizes. These wheels are great for cyclists who want to increase their speed, who are training, or competing.

Mountain bike tires and sizes

  • 26”: These wheels provide good maneuverability and stability while riding but lack in rolling over larger obstacles and rolling fast on flatter sections of trail.
  • 27.5”: 27.5-inch tires and wheels are the newest size to be introduced to mountain biking, they combine the handling and maneuvering confidence of 26” wheels with the rollover ability of larger wheel sizes.
  • 29”: 29-inch or 29er wheels and tires are the fastest rolling of all the wheel sizes. Most commonly used for cross country mountain bike racing, these wheels can roll over moderately large obstacles quite easily and roll the fastest on flat sections of trail or road.

Tubes vs. tubeless

Most bikes run rubber tubes inside of the tires to allow the bike to roll without damaging the rims. However, many riders are converting their bikes over to a tubeless setup. The rims are taped with a special tubeless tape to prevent leaks and tubeless ready tires are put onto the rims. Then the tires are filled with tubeless sealant that will seal holes and leaks and allows the rider to remove their tubes from the tires, saving weight and removing the possibility of getting a flat tire.