Which Size Bike Crank Arms To Use?

The three most common crank lengths for bicycles are

170mm, 172.5mm and 175mm

. What size your bike has will likely depend on what size the frame is. Small bikes tend to come with 170mm cranks, medium with 172.5mm and large with 175mm.

What is the standard crank arm length?

Cranks are measured from the centre of the pedal axle to the centre of the bottom bracket spindle. Lengths most often range from

160mm up to 185mm

, in 2.5mm increments, and typically bigger bikes will come with longer cranks.

Are shorter crank arms better?

If the gearing isn’t adjusted, the shorter crank arm effectively gives a harder gear in terms of the force required at the pedal to create a given propulsive force at the wheel, potentially leading to more strain on the body when you run out of gears.

Are all bike crank arms the same?

Most stock bikes have cranks of 170mm or 175mm, but you can get them as short as 140mm and as long as 190mm

. Choose crank arms that suit your inside leg measurement for optimum comfort and control.

What is 170mm crank?

Why are we using the same range of crank lengths? The answer to that is that we probably aren’t. 30 years ago, 170mm was ‘normal’, 172.5mm was longish and 175mm was considered to be quite a long crank and relatively uncommon. Whereas now 170 is

‘short’

172.5mm is ‘normal’ and 175 mm cranks are very common.

Are 175 cranks too long?

Basically,

Shimano thinks 170 to 175mm is the Goldilocks zone of crank length for most people and most bikes

.

Are shorter cranks better for knees?

Just by installing shorter crank arms, without any other adjustment, the knee at maximum flexion is lowered by 7.5 mm

. That difference provides approximately 3° to 4° of relief.

Are longer or shorter cranks better?

Meanwhile, a longer crank allows a rider to push/pull harder ratios but makes it more difficult to maintain a high cadence. So

the shorter cranks are recommended for those who engage in competitions with numerous changes of pace and for those who naturally pedal with a higher cadence

.

How do I know what crankset to buy?

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.

Are longer crank arms better for climbing?

If you’re having problems with your lowest gear, stick with longer cranks

. They reduce force at the same gear ratio. Shorter cranks allow you to use a lower gear at the same foot speed… but if you don’t have a lower gear, you’re stuck. Right.

What are the benefits of shorter cranks?

Less pressure/discomfort on the knee at the start of the down stroke

. More space at the top of the pedal stroke between upper leg and torso. this is not only because the crank is shorter but also because there is more space for the foot to dorsiflex on the up-stroke. Easier to pedal in the saddle going up hill.

What is the difference between 172.5 and 175 cranks?

From 172.5mm to 175mm, you have only

2.5mm

difference. We set our saddle height when the pedal is at 6 o’clock position. So you should lower the saddle for 2.5mm, since your pedal is 2.5mm lower than it was.

Will any crankset fit on my bike?

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 all Shimano crank arms compatible?

Shimano road cranks are interchangeable between other component levels that utilize the dual pinch bolt

. Nearly all pinch-bolt style Shimano road cranks are able to be interchanged in equivalent lengths.

Can you put any crank on a bike?

Every brand has its specifications when it comes to cranksets. In addition, different models of the same brand also have diverse bottom brackets specifications. These differences make it

impossible to put any crankset on a bike

.

What size cranks do I need for mountain bike?

Does crank length affect gear inches?

Crank length changes the feel of the drivetrain no matter the gearing

. Longer cranks do not have the same affect/feel as a lower gear ratio, nor are shorter cranks the same as a higher ratio.

Does crank length affect power?

Folk lore suggests that

crank length has a huge effect on the power that you can generate

, or the cadence that you’re able to ride at. Namely, the general view is that shorter cranks allow you to spin and accelerate quicker but at the cost of high torque or power.

Does crank length affect saddle height?

The main points to consider: handlebar height and saddle setback.

Handlebar height is always set relative to saddle height

. That 5-foot-2 woman moving to 165mm cranks will raise her seat about 7.5mm to compensate for the shorter cranks.

What crank length do the pros use?

Does bike crank length matter?

Crank length can be used as a tool to improve fit related issues impacting comfort, power, and aerodynamics

. Moving to a shorter crank can improve: Comfort: A shorter crank length reduces range of motion at the knee (extension and flexion), hips, and low back.

Are shorter cranks better for climbing?

“I try to put anyone on the longest crank possible within their range of movement to use the muscle mass they have,” he said. “This is especially important for strength-oriented riders.

For those riders with greater cardiovascular strength, a shorter crank works better because they tend to ride at higher cadences

.”

Does crank length really matter?

What is a good length for a bike ride?

Well, despite the seemingly open-ended nature of this question, I’ve conducted extensive research, and I’m pleased to report that it does, in fact, have a quantifiable answer. The ideal length for a bike ride is

20 miles

.