Parts of a Bike Pedal: Pedal Anatomy Explained

Parts of a bike pedal that every type shares

Every bike pedal, from a resin kids’ pedal to a carbon race pedal, is built on the same core: a spindle fixed to the crank, a body that turns around it, and bearings or bushings in between.

Part	Also called	What it does	Common problem
Spindle	Axle	Threads into the crank and carries the body	Bent spindle, worn bearing surfaces
Thread	Pedal thread	Holds the spindle in the crank arm	Stripped crank threads
Wrench flats / hex socket	Pedal flats	Where the tool grips to fit and remove the pedal	Rounded flats or hex
Seal	Dust seal	Keeps water and grit out at the crank end	Torn seal lets water in
Bearings / bushings	—	Let the body spin smoothly	Play, roughness, grinding
Lock nut	Axle nut	Holds the body on the spindle at the outer end	Works loose, body wobbles
Dust cap	End cap	Covers the lock nut and seals the outer end	Lost cap, dirt in the bearings
Body	Platform	The part your foot pushes on	Cracks, worn grip

The rest of this guide goes through each part, then the extras that make a pedal flat, cage or clipless.

Spindle (axle)

The spindle is the steel shaft at the center of the pedal. One end threads into the crank; the body spins around the rest.

Most spindles are chromoly steel. Stainless steel resists corrosion, and titanium saves weight but needs anti-seize on the threads. Some pedals are sold with longer spindles to widen your stance.

On many pedals the spindle comes out as a complete axle unit with its bearings, so a worn or bent spindle can be replaced without buying new pedals. Options are in pedal spindles.

Thread, wrench flats and hex socket

The thread is the part of the spindle that screws into the crank. Adult bikes use 9/16” x 20 TPI; one-piece cranks on many kids’ bikes and cruisers use 1/2” x 20 TPI. The left pedal is reverse threaded.

Between the thread and the body you will find one or both of these:

• Wrench flats: usually 15 mm, for a pedal wrench.
• Hex socket: in the end of the spindle, usually 6 mm or 8 mm, reached from behind the crank.

Many modern flat pedals have the hex only, so check before you reach for a pedal wrench. Our pedal thread sizes guide explains how to tell 9/16” and 1/2” apart.

Bearings and bushings

Bearings and bushings sit between the spindle and the body so the pedal turns freely. There are three main types:

• Cup-and-cone (loose ball): loose steel balls running between a cup in the body and a cone on the spindle. Adjustable and serviceable, common on classic quill and cage pedals.
• Cartridge bearings: sealed bearing units pressed into the body. Low maintenance; replaced rather than adjusted.
• Bushings: plain sleeves, often DU or igus types, that the spindle turns inside. They take heavy loads in a small space.

Many modern pedals combine them, typically an inner bushing near the crank with one or more cartridge bearings toward the outer end. Side-to-side play or a rough feel means they need attention; see how to service pedal bearings.

Lock nut and dust cap

The lock nut (axle nut) threads onto the outer end of the spindle and holds the body on. On cup-and-cone pedals it also locks the cone in place, setting how tight the bearings run.

The dust cap (end cap) covers the lock nut and keeps grit out of the outer bearing. Some thread in, some press in. Removing it is the first step of any bearing service, and a lost cap is worth replacing quickly before the bearing fills with dirt.

Flat pedal parts: body, pins and concave

A flat pedal adds a wide body and a way to grip the shoe.

• Body (platform): nylon composite or aluminum, sized to the shoe.
• Pins: threaded steel studs that bite into the sole. Budget pedals use molded nubs instead. Pins can load from the top or from underneath.
• Concave: a slight dish in the top surface that cups the foot.
• Leading edges: the front and rear edges, often chamfered so they glance off rocks.

Replaceable pins are one of the clearest signs of a good flat pedal, because a bent or snapped pin is a cheap fix. See pedal pins and our flat pedals guide.

Cage pedal parts: cage plates, toe clip holes and reflectors

A cage pedal builds the platform from two metal plates, one at the front and one at the back, joined to a central body around the spindle. Your shoe rests on the plates’ edges, which are often serrated for grip.

Cage and quill pedals carry the fittings for traditional foot retention:

• Toe clip mounting holes: two holes in the front plate where a toe clip bolts on. They often double as the mounting for the front reflector.
• Strap slots: gaps at the inner and outer ends of the pedal that a toe strap runs through.
• Quill: on road quill pedals, a raised tab on the outer rear edge that stops the shoe sliding outward.
• Reflectors: front and rear reflectors, common on commuter pedals and rare on mountain-bike flats.

To fit clips, remove the front reflector and bolt the clip into the same holes. More on choosing them in cage pedals.

Clipless pedal parts: jaws, spring and tension screw

A clipless pedal swaps the platform for a mechanism that grabs a cleat on the shoe sole. The parts vary by system, but most share these:

• Front hook (front jaw): the fixed lip you push the toe of the cleat into first.
• Rear jaw (binding): the hinged part that snaps shut behind the cleat when you press down.
• Spring: holds the rear jaw closed. It sets how firmly the pedal holds and how much force it takes to twist out.
• Tension screw: a small adjuster, usually a hex bolt at the back of the mechanism, that changes spring preload. Shimano SPD and SPD-SL pedals have one.
• Body: a small platform around the mechanism on road and trail pedals, or almost nothing on minimalist mountain-bike pedals.

Not every system follows that layout. Crankbrothers pedals use spring-loaded wings with no tension screw, and Wahoo Speedplay puts the spring in the cleat rather than the pedal.

The cleat is the other half of the system. It bolts to the shoe: 2 bolts for SPD-style mountain and commuter shoes, 3 bolts for SPD-SL and Look road shoes, and 4 holes for Speedplay. Its shape sets the float, the free rotation before release, which our guide to cleat float covers. Compare complete systems on our clipless pedals page.

L and R markings

Every pedal is made for one side, and the markings save you from cross-threading a crank.

• Letters: look for L and R stamped on the spindle end, the wrench flats or the body.
• Grooves: some makers machine a groove or notches into the left spindle as a second marker.
• Thread direction: with the spindle pointing up, right-pedal threads rise to the right and left-pedal threads rise to the left.
• French pedals: older French pedals may be marked D (right) and G (left).

R goes on the chainring side. If a pedal will not spin in by hand, check the markings before using a wrench; our guide to which pedal is reverse threaded explains why.

Which pedal parts can you replace?

Many pedal parts can be replaced, so a worn pedal is not always a dead pedal.

Part	Usually replaceable?	Notes
Pins	Yes	Match thread and length to the pedal
Cleats	Yes	Wear items; replace when release gets vague
Axle unit or spindle	Often	Ordered by pedal model
Bearings and bushings	Often	Rebuild kits from many makers
Dust cap	Often	Lost caps let dirt in fast
Reflectors and toe clips	Yes	Share the front mounting holes on cage pedals
Body	Rarely	A cracked body usually means a new pair

If you are replacing more than two or three of these at once, compare the cost with a new pair before you start.