How Shorter Cranks Improve Energy Efficiency and Rider Performance

Crank length comparison and foot distance per minute

Shorter crank lengths are often discussed for aerodynamic fit or joint comfort, but recent findings point to something even more compelling: energy efficiency. A study by Speed & Comfort explores how shorter cranks reduce total muscle energy expenditure without sacrificing power. This article breaks down the three core hypotheses behind this approach and what it means for cyclists seeking long-distance performance gains.

Hypothesis 1: Power output can be maintained by increasing cadence

When you shorten crank length, torque decreases. But that loss can be compensated by increasing cadence (rpm). This means that for the same downward force on the pedals, a rider can maintain their power output simply by pedaling faster. Most trained cyclists can adapt to this without issue.

For example, moving from 175mm to 165mm cranks requires only about a 5 rpm increase to produce the same power output. The 145mm cranks may require a cadence increase of about 18 rpm. This proves power loss from shorter cranks is not absolute. It’s adaptable.

Hypothesis 2: Shorter cranks reduce muscle energy usage

The human body expends energy not just in outputting watts, but in internal muscle activity. The study highlights how shorter cranks reduce total muscle contraction distance per pedal stroke. That means lower contraction velocity, which directly leads to less heat generation and energy waste, especially in fast-twitch muscle fibers.

In testing, a switch from 175mm to 165mm cranks resulted in about 5.8% less foot travel per revolution. This translates to lower overall energy expenditure per minute, particularly valuable in long-distance riding or time trialing where efficiency matters most.

Hypothesis 3: Less energy, same power, better comfort

When you combine Hypotheses 1 and 2, a new truth emerges. Shorter cranks let you ride with less physiological stress while maintaining power. That means longer sustainable effort, better posture, and fewer injury risks.

By freeing up hip angle, shorter cranks also improve aerodynamic posture and breathing. This has cascading benefits in time trials, Ironman races, and even daily training rides. All of this adds up to a meaningful performance advantage, especially over long distances or multi-hour efforts.

Final takeaway

Shorter cranks are not just a fit choice. They are a performance tool. Whether it is reducing fatigue, improving mechanical efficiency, or enabling better aero, the science supports what riders have reported for years. Shorter cranks help you go further, faster, and with less strain.


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