What is a Crank Arm on a Bike? (Well Explained)

In case you are new to this, Crank Arms are the levers to which your pedals attach. The two crank arms, right and left, are connected to the pedals and to every other through the bottom bracket axle.

Cranks are the components that actually transfer power to the chainring from the pedal.

The chain is what turns the rear wheel when you are pedaling.

What is a crank arm on a bike? (Well Explained)

The Bottom Bracket is the housing that actually holds the bearings in place and also the axle that the crank arms attach to.

What do Crank arms attach to?

It includes one or more sprockets, which are also called chain or chainrings wheels connected to the cranks, arms, or crankarms to which the pedals attach.

The rider connects to it by the pedals, to the bike frame by the bottom bracket, and to the rear sprocket, cassette, or freewheel through the chain.

When should I change my bike crank?

Noisy/Rough running is the easy way to notice when a chainring needs replacing, unless a chainring is well beyond its service life it is very challenging to determine this visually, chainring teeth easily take on the shape of a shark’s fin in use.

Can you put any crankset on a bike?

Cranksets do not seem to be always replaceable because every crank is made to work with a specific bottom bracket.

Whether or not the cranks use the identical interface (square taper, octa link, or hollow tech), switching them between bicycle brands or perhaps models of the same brand is tough.

What does a crankset include?

The crankset also called the chainset, includes chainring, crank arms, and bottom bracket. Chainsets are available in three main formats, single, double, and triple.

The introduction of giant rear cassettes in recent years has improved the viability of single chainrings.

How are bike crank arms made?

In a strategy of producing a hollow bike crank arm, a sand mold core is placed into a casting mold in order that a melt space is created around the sand mold core, molten metal is poured into the casting mold, and therefore the molten metal is solidified to create a crank billet.

How do I know what crankset I need?

Cranks are available in a range of sizes, most ordinarily from 165mm-190mm, and ideal crank length is usually determined by three factors:

  • Your height
  • Your cycling discipline
  • Your personal preferences

If you modify your crank length, it’ll change how it feels to pedal your bicycle, and it may also change your fit on your bicycle.

Is the crankset compatible with a mountain bike?

Many cranks are compatible with a range of the simplest 1x chainrings for mountain bicycles, so you’ll not need to search around too far when looking to replace a worn-down chainring or even swap out for a different number of teeth.

Why is my crank wobbling?

The stability of the pedal crank can really affect the stability of the pedals, a standard reason for wobbly pedals may be a loose or damaged bicycle crank.

The screws that connect the crank arm to the crank and to the pedals can be knocked loose when the bicycle falls or over time.

How long does a bike crank last?

Only if you check your crank arms regularly for tightness they can last for years and years.

I still have vintage Sugino Aero Tour (AT) crank arms that I have used for over ten years without any wear to the square tapers.

How long does a road bike crank last?

A steady rider who stays on the big ring keeps the drivetrain clean, does not allow the chain to get too long before replacing it, and started with good quality components can get 60,000+ miles out of a chainring.

Why does my crank arm keep coming loose?

Keep in mind that your bicycle crank arms and pedals go through the most pressure while you are riding your bicycle.

That’s the reason loose crank arm is a common issue every cyclist faces.

But it can also happen due to broken threads or loose bolts or perhaps damaged bearing.

How do I identify a Shimano crank?

Shimano cranks are discovered with model information above or surrounding the area on the backside of the pedal threads.

For instance, FC-6700/6750 = Shimano Ultegra. The crank length is commonly located within the same area, which is useful to notice before placing an order.

Are all Shimano cranksets the same?

All Shimano Chainsets are not the same, they differ in pedal diameter, crank arm length, etc.

Shimano Crankset Parts are not replaceable, but they’re compatible. Shimano makes several types of cranksets geared for different cyclists.

Should I upgrade my crankset?

You can absolutely upgrade your crankset,  the most purpose of upgrading your crankset is to improve performance and that means adjusting or replacing your bicycle crankset to get an improved experience.

How long do bike crank bearings last?

That can depend on too many factors to make any generalizations. Properly adjusted, and discounting weather-related factors, all the bearings on a bicycle suppose to last close to forever.

Back within the old days of “primitive” steel spindles and threaded cup bottom brackets, most would outlast the bicycle.

What is the best crank length for MTB?

Trail/Enduro 170mm crank arm length is the most ordinarily used size and is recommended to keep a decent leverage ratio and have a little bit more ground clearance because of having more travel.

Does crank weight matter?

A lighter crank and the same saddle are going to be your best improvement and as for the saddle, it is actually a personal item and you must not give up comfort for less weight because nothing is worth being impotent

What do longer crank arms do?

It changes gear, if you want to change crankarm lengths, it will change your gearing.

The relative jumps between gears remain the same, but the overall range can feel a bit simpler to pedal with shorter cranks and harder with longer ones.


In conclusion, crank arms are one of the most important parts of the bicycle because they allow you to convert the power produced by your legs into rotational motion that drives the bike forward.