Research · Crank length
Should you go shorter?
Across cranks from 120 to 220mm, maximum power moves about 4% — the lever was never where the watts were.
For decades crank length was set by leg length and left alone. Now riders on 172.5 and 175 are dropping to 170, 165, even shorter — chasing hip comfort and a lower front end, and finding the power cost they feared isn't really there.
Reviewed July 2026 · 5 sources
- Within the range people actually ride, crank length has no meaningful effect on power or efficiency. A foundational 2001 study found only ~4% variation in maximal power across an extreme 120–220mm span; a 2025 randomized trial found no difference in efficiency or sprint power between 165, 170 and 175mm.
- That 2025 trial did find one objective benefit: riders reported significantly lower perceived fatigue on 165/170mm than on 175mm.
- Shorter cranks open the hip angle at the top of the stroke — which is why fitters prescribe them for hip, knee and low-back comfort, and to let a rider hold a lower, more aerodynamic position.
- The trend is pro-led and real: Tadej Pogačar has raced 165mm; Wout van Aert and Lizzie Deignan are among many cited by fitters and cycling media.
- Riders switching shorter commonly report reduced knee/hip/back strain and easier high-cadence spinning, especially in an aggressive position.
- Most say adaptation runs from immediate to a few weeks, and that they wouldn't go back — though some miss low-cadence torque on steep climbs.
- Whether shorter cranks deliver a net aero/power gain via a lower position — beyond comfort — isn't settled; the oft-quoted drag reductions come from individual cases, not controlled population data.
- Optimal length is highly individual, and a crank change is a fit change: it lowers your effective saddle height, so a swap done in isolation can feel worse. Judge it only after the rest of the fit is re-set.
Why this is happening now
Two forces converged. Aerodynamics pushed riders toward lower, more closed positions, and a shorter crank makes that position liveable by opening the hip at top-dead-centre. At the same time, the lab caught up with what fitters suspected: within the range people ride, crank length barely moves sustained power. Take away the power penalty and the comfort and aero upside stand on their own.
The pro peloton made it visible — riders on strikingly short cranks — and component makers followed, so 165mm and shorter are now stocked as normal road options rather than a niche.
What actually changes when you go shorter
The lever gets shorter, so at the same gear and speed your cadence rises slightly and each stroke asks a little less peak force from the knee and hip. The headline effect riders feel is space: the knee comes up less far, the hip closes less, and a low position stops fighting you.
The catch is that a crank change is a fit change. Drop crank length and your effective saddle height drops with it, so the saddle usually needs to come up (and often forward) to keep the same leg extension. Judge the swap only after the rest of the fit is re-set to match.
Sources
- Determinants of maximal cycling power: crank length, pedaling rate and pedal speedMartin & Spirduso, European Journal of Applied Physiology · 2001Across a 120–220mm range, maximal power varied only ~4%; pedal speed, not crank length, is the dominant determinant of power.
- Effects of crank length on cycling efficiency, sprint performance, and perceived fatigueJournal of Exercise Science & Fitness (via PubMed) · 2025Randomized crossover, 28 trained cyclists: no efficiency or 6s sprint-power difference across 165/170/175mm, but significantly lower perceived fatigue on 165/170.
- Should you fit shorter cranks on your bike?road.cc · 2024Fitter-driven feature; Phil Burt (ex-British Cycling physio): “I’m yet to meet a rider who wouldn’t benefit from shorter cranks.” Also lists the downsides.
- What's the optimal crank length for you? How to calculate the best setupCycling WeeklyMainstream explainer of sizing methods and the shift toward shorter defaults.
- Crank Length & Bike Fit: Myths DebunkedMyVeloFit Fit AcademyFrames crank length as a fit/hip-angle lever rather than a power lever.