The debate between 170mm and 175mm crank arms is more than just a matter of millimeters. Crank length directly affects your biomechanics on the bike — influencing leverage, cadence, and overall comfort during pedaling.
170mm crankarms are often seen as the default in road cycling. They provide a smooth pedal stroke and are generally well-suited for riders of average height. The shorter length allows for quicker cadence and better hip clearance, which can be helpful in aero positions or when climbing out of the saddle.
Riders with shorter inseams or those recovering from injuries may also benefit from the reduced range of motion required by 170mm cranks.
175mm crankarms, on the other hand, are commonly used in mountain biking and by taller riders. The longer lever can increase torque, making it easier to generate power on steep climbs or when accelerating from low speeds.
However, they also require a greater range of motion, which can place more strain on the knees and hips — especially on long rides or when the bike fit is not perfectly dialed in.
The difference in feel between 170mm and 175mm may seem subtle, but over time it can influence fatigue, efficiency, and even injury risk. Crank length also affects your bike’s gearing and pedal clearance. A longer crank changes the timing of your stroke and can alter the fit dynamics of your saddle and cleat position.
Many modern riders are now experimenting with shorter cranks — even below 170mm — to improve cadence and reduce joint compression. Still, for those seeking raw leverage and slow-cadence power, 175mm remains a reliable choice.
When choosing between 170mm and 175mm, consider your height, flexibility, riding discipline, and bike fit. The best crank length is the one that allows you to pedal efficiently, comfortably, and injury-free.
At CARBONRAW, we analyze how crank length, material, and design all influence performance. Whether you choose QO carbon cranks or models from ROTOR, SRAM, or Easton, understanding crank length is key to dialing in your drivetrain.