How cadence affects crank torque
The relationship between power and torque
Power at a rotating crank is torque multiplied by angular velocity. Cadence tells us revolutions per minute; multiply by 2π and divide by 60 to express that rotation in radians per second.
Keep power at 250 W. At 60 rpm the average crank torque is about 39.8 N·m; at 100 rpm it is about 23.9 N·m. Turn the control and watch the model respond. These are direct calculations, not force-plate measurements. Use the comparison to understand what changes at the crank when you shift or choose a different cadence.
Schematic crank. Drag to rotate. Individual biomechanics are not modelled.
The relationship between power and torque
Power at a rotating crank is torque multiplied by angular velocity. Cadence tells us revolutions per minute; multiply by 2π and divide by 60 to express that rotation in radians per second.
Keep power at 250 W. At 60 rpm the average crank torque is about 39.8 N·m; at 100 rpm it is about 23.9 N·m. Turn the control and watch the model respond. These are direct calculations, not force-plate measurements. Use the comparison to understand what changes at the crank when you shift or choose a different cadence.
How torque changes through the pedal stroke
The displayed torque is the equivalent average across rotation. Real torque varies through the stroke and between legs. A rider does not apply the same force at every angle.
Our model shows the mechanical relationship only. The crank does not reproduce an individual’s joint motion, muscle activation or left-right balance. The visual makes the rotation visible; it cannot diagnose a pedalling technique.
Is there an ideal cadence?
Lower torque per revolution does not establish a universally better cadence. In an experiment with fourteen elite male cyclists, cadence affected efficiency and performance, with important differences between imposed and freely chosen cadences. This is a specific experiment, not a rule that every rider should copy one rpm.
Choose a familiar cadence, then inspect what changing it requires mechanically. Keep comfort, task, terrain and fatigue in the picture.
How gearing affects cadence
At a given road speed, selecting a lower gear lets the crank rotate faster relative to the wheel. The torque and rotation relationship changes while the external road demand remains.
A gear change does not create free power. It changes how you deliver the power. The next experiment follows that connection from crank to rear wheel.
Why the same watts can feel different
At a given crank power, turning more slowly requires greater average torque; turning faster requires less average torque per revolution. That does not directly tell you the force on a particular muscle or joint, because body position, crank angle and how each leg applies force all matter.
For a 170 mm crank, the 39.8 N·m average torque in the 250 W, 60 rpm example is equivalent to about 234 N of tangential force at the pedal. At 100 rpm the equivalent average is about 140 N. Actual pedal force changes throughout the stroke and is not all tangential.
Why lower torque is not automatically easier
Faster pedalling reduces the average crank torque needed for the same power but asks the legs to cycle more quickly. Coordination, muscular activation and the energy cost of moving the limbs all change. Lower cadence increases torque demands but does not automatically make an effort better or worse.
In a laboratory experiment with fourteen elite male cyclists, performance and gross efficiency varied across imposed cadences. Those results are useful evidence that cadence matters; they do not establish an ideal number for every rider, power level or terrain.
Try it on a familiar section
At a steady, comfortable power, shift one gear and observe how cadence and pedal pressure change. Compare short sections where power and conditions are similar, and pay attention to comfort and control rather than trying to imitate a specific number.
On a climb, shifting earlier can help avoid forcing a difficult change under high load. If cadence falls late in a long effort, inspect the power, terrain and gearing before assuming it identifies a particular muscle or technique problem.