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Questions and answers about sports

How can I know if a crankset is compatible with my bike without physically seeing it?

5 min read

Asked by: Christopher Bandow

How do you know what cranks will fit your bike?

Cranks come in a range of sizes, most commonly from 165mm to 190mm, and ideal crank length is often determined by three factors: your height, your cycling discipline and your personal preferences. If you change your crank length, it will change how it feels to pedal your bike, and it may change your fit on your bike.

How do I know what size crankset I need?

How to measure crank length? Crank length is measured from the centre of the bottom bracket axle to the centre of the pedal axle. If you’re not sure what length the cranks on your bike are, the quickest way of finding out is typically to just look at the backside of your cranks, just below the pedal axle.

Do all cranksets fit all bottom brackets?

In general terms, most cranksets can be fitted to a variety of bottom bracket shells, though much of this compatibility depends upon the availability of suitable hardware (see next section). Any incompatibilities that do arise are often related to the length and/or diameter of the crank axle.

Are cranks interchangeable?

No, cranks are not generally always interchangeable, but you probably can transplant the crank from the broken bike. First, do both bikes have 6, 7 or 8 sprockets in the rear cluster? If so, they use the same chain width and the spacing between the chainrings will be the same.

Do all cranksets fit all bikes?

Crankset compatibility. You can replace the chainrings on your crankset, but not all chainrings will fit all cranks. First, different cranksets may have a different number of arms or direct-mount interfaces (connecting the cranks to the chainrings), and they may be positioned differently.

Can I put a bigger crankset on my bike?

Yes, you can. This will make it suitable for diverse terrains and make pedaling easier. Putting a smaller chainring on your road bike isn’t a problem but you may have to change your crankset.

How do I know which bottom bracket I need?

To find out the size of bottom bracket needed, measure the inside of the bottom bracket shell in your frame, it will be 73mm, 70mm or 68mm. Some older frames may have Italian threaded bottom brackets, instead of the more modern English.

Why are shorter cranks better?

They allow more fluid, comfortable pedalling. They can reduce or eliminate lower back, hip and knee pain. For triathletes the transition from cycling to running becomes easier. Shorter cranks can even make your saddle comfier.

Are shorter cranks better for knees?

In other words, a shorter crank does give you less leverage, but that shorter crank arm allows your downstroke to start where your body can create more power. This (according to the Canfields) produces more power and (according to the study cited below) is better for your knees and hips.

Can I put any bottom bracket on my bike?

To a certain extent which bottom bracket you end up buying is up to what kind of frame you have. Certain frame materials and drivetrain options only support one type of Bottom Bracket. There are two main types of bicycle bottom brackets in today’s market, namely, threaded and press-fit BB’s.

Is BB92 the same as PF92?

The frame’s bottom bracket shell inner diameter is 37mm. A bearing with an OD of 37mm is pressed directly into the frame. Trek is moving away from the BB90/95 system to what they call PF92, which is the same as a BB92 (41mm ID shell and 92mm width).

How many BB spacers do I need?

A 68mm or 83mm bottom bracket shell needs two of the 2.5mm spacers on the drive (chainring) side and one 2.5mm spacer on the non-drive side.

Can you mix crank arms?

generally, yes. The early days of Stages had people mixing different crank arms together, different colors sometimes, different Q factors too. This might be obvious, but just to put it here – the crank interfaces need to match, you can’t just put two different ones together.

Can I use an 11 speed crank on a 8 speed bike?

Nominally no, an 11 speed speed crank will not work with an 8 speed drivetrain.

Are bike crank arms interchangeable?

Cranksets are not always interchangeable. Every crank is designed to work with a specific bottom bracket. Even if the cranks use the same interface (octalink, square taper, or hollow tech), switching them between bike brands or even models of the same brand is hard.

What’s the difference between 170mm and 175mm cranks?

Still though, the difference between 170 mm and 175mm is less than 3% and leg lengths of bike riders vary by far more than that. There is a school of thought, particularly in the United States, which suggests that crank length should be proportionate to leg length.

How do I know which bottom bracket is compatible?

To find out the size of bottom bracket needed, measure the inside of the bottom bracket shell in your frame, it will be 73mm, 70mm or 68mm. Some older frames may have Italian threaded bottom brackets, instead of the more modern English.

How do I know my bike pedal size?

If you want to know your bike pedal size you can check the width of the thread with a set of digital callipers. Alternatively you can ask the manufacturer of the crank or you can take your bike to a local bicycle service repairs / local bike shop and ask them to clarify the pedal thread size needed.

What is a 50 34 crankset?

Compact chainset

A compact chainset has a 50-tooth outer chainring and a 34-tooth inner chainring. This means that the gears are lower (easier to turn, but they’ll progress you a shorter distance per pedal revolution) than you get with a 53/39 chainset (above) with the same cassette.

What is faster 9 speed or 11 speed?

11-speed cassettes are absolutely not faster than 9-speed cassettes. The factor that determines the speed of your bike is you; the rider. Putting an 11-speed cassette on your bike will not magically produce more speed. It will, however, allow you to find the correct gear more easily.

Are bigger cranks faster?

Then, longer cranks allow a rider to develop more speed than shorter cranks, even when the difference is as little as 2mm.