Which Is Better, a 170mm or a 175mm Crank Arm?

This choice looks small, but it affects every pedal stroke. When you’re upgrading a crankset or dialing in a bike fit, you’ll often land on this exact question: which is better, a 170mm or a 175mm crank arm? The right answer depends less on strength and more on fit, comfort, and how you ride.

The Short Answer

Neither 170mm nor 175mm is universally better. A 170mm crank usually favors comfort and cadence, while a 175mm crank can feel more natural for taller riders with longer legs.

The best choice is the one that fits your body and riding style.

The Real Difference Between 170mm and 175mm

The difference is only 5mm, but that change affects joint angles and leg movement.

• 170mm cranks reduce how much your knee and hip bend
• 175mm cranks increase leverage but require more range of motion
• That motion repeats thousands of times per ride

Over time, those millimeters matter.

Why Some Riders Prefer 170mm Cranks

Shorter cranks are becoming more popular.

• Less hip compression at the top of the pedal stroke
• Reduced knee strain
• Easier high-cadence spinning

Many riders describe 170mm cranks as smoother and more comfortable.

Why Some Riders Prefer 175mm Cranks

Longer cranks still have their place.

• Feel more natural for taller riders
• Slightly more leverage at lower cadences
• Common on bikes sized for long legs

Riders who like to grind big gears may prefer this feel.

Power Output: Is One Faster?

This surprises many cyclists.

• Power output is usually the same with both lengths
• Cadence naturally adjusts to crank length
• Efficiency matters more than leverage

Power comes from how you pedal, not just crank length.

Comfort and Injury Prevention

Comfort often decides the winner.

• 170mm cranks reduce joint stress
• 175mm cranks demand more flexibility
• Shorter cranks help riders with knee or hip issues

If comfort improves, performance usually follows.

Bike Fit Matters More Than Height Alone

Many riders choose based on height, but that’s only part of the story.

• Leg length matters more than total height
• Flexibility changes what works best
• Saddle and bar position interact with crank length

This is why professional bike fits often recommend shorter cranks.

Riding Style Makes a Difference

Your riding style should guide the choice.

• High cadence and endurance riding → 170mm
• Low cadence and torque-focused riding → 175mm
• Aero positions benefit from shorter cranks

There’s no one-size-fits-all answer.

Who Should Choose 170mm?

• Riders prioritizing comfort
• Cyclists with joint sensitivity
• Those who spin at higher cadence

Who Should Choose 175mm?

• Taller riders with long legs
• Cyclists comfortable with lower cadence
• Riders who prefer a traditional feel

Frequently Asked Questions

Which is better, a 170mm or a 175mm crank arm?

Neither is universally better—it depends on fit, comfort, and riding style.

Will switching from 175mm to 170mm reduce power?

No, most riders maintain the same power with improved comfort.

Is 170mm too short for tall riders?

Not necessarily. Many tall riders benefit from shorter cranks after proper fitting.

Final Verdict

So, which is better, a 170mm or a 175mm crank arm? The one that fits your body best.

For most modern riders, comfort and efficiency favor 170mm, while 175mm still works well for those with longer legs and a preference for leverage. The best choice is the one that lets you ride longer, smoother, and pain-free.