Short Cranks: Why the Pros Went 165 mm (and It Isn't About Your Legs)
For decades the rule was simple: taller riders ride longer cranks, because a longer lever means more power. In 2025 and 2026 the fastest riders in the world did the opposite. Tadej Pogačar and much of the pro peloton dropped to 165 mm cranks and shorter — and they didn't get slower. The reason is the interesting part: short cranks are barely about your legs at all.
The one-line version
A crank is a lever, and a long one drives your knee high into your chest at the top of each stroke. That closes your hip angle — costing you power and crowding your lungs. A shorter crank opens the hip, which lets you rotate your pelvis forward and drop your torso into a more aerodynamic shape you can actually sustain. The leg-power cost is small to none; the fit and aero upside is real.
Why a shorter lever helps
Picture the top of your pedal stroke. With a long crank, the pedal sits higher, so your knee comes up further toward your chest. That does three unhelpful things, and they're backed by biomechanics research on crank length:
- It weakens your stroke. A very closed hip puts your muscles at a poor length for producing force.
- It loads the joints. More knee and hip flexion means more load through the kneecap and a backward pelvic tilt that stresses the lower back.
- It crowds your lungs. In an aggressive position, the thigh coming up toward a low chest compresses the diaphragm and limits how much you can breathe.
Shorten the crank and the pedal doesn't rise as far at the top. Your knee stays lower, your hip stays more open — and that opened hip is what unlocks everything downstream.
What the evidence shows
This is where it stops being folklore. Controlled biomechanics testing found that minor crank-length reductions significantly cut peak knee flexion by up to 24% and hip flexion by up to 13% versus 175 mm cranks — with lower perceived fatigue, not higher. Critically, separate efficiency and sprint testing found no meaningful loss of power or efficiency from going shorter. The old "less leverage = less power" fear largely doesn't show up in the data.
The aerodynamic link is indirect but powerful. Because the rider's body is around 80% of total aerodynamic drag, the fastest free speed comes from getting your torso lower — and the opened hip angle from shorter cranks is exactly what lets you rotate your pelvis forward and drop the front end toward a time-trial-like, torso-parallel position without folding yourself in half.
Short cranks don't add leverage. They open your hip so you can get lower and still breathe — that's where the speed is.
One widely reported figure attributes an average ~15-watt FTP gain to a switch to 165 mm cranks (via cleaner passage through the pedal dead zones and better breathing). Treat that as indicative rather than a controlled-trial result — but it points the same direction as the peer-reviewed kinematics and efficiency work.
The catch: you have to re-set your fit
Here's the mistake that ruins the switch. A shorter crank lowers the bottom of your pedal stroke — so if you bolt on shorter cranks and leave the saddle where it was, your leg extension is now too short and the whole benefit is muddied. Raise the saddle by the crank difference to keep the same extension. Your reach to the bars also opens up slightly, so re-check it.
Geometry only: a shorter crank lowers the bottom of the pedal stroke, so to keep the same leg extension you raise the saddle by the crank difference (and vice-versa). Your reach to the bars also opens a touch — re-check it. This is a starting point, not a substitute for a proper bike fit.
The comfort–aero trade-off (still applies)
Short cranks don't repeal the rule from aero position: the lowest position only helps if you can hold it, at power, for the whole ride. What shorter cranks do is raise the ceiling — they let you get lower before your hip angle closes down and your breathing suffers. You still have to earn the position with flexibility and core strength, and still stop lowering the front end at the point where power or breathing drops off. Short cranks give you more room to work with; they don't do the work for you.
How to switch
- Treat crank length as a fit lever, not a power lever. The win is a more open hip and a lower sustainable torso — not more torque.
- Know when it's worth it. If you're on 172.5-175 mm and feel cramped at the top of the stroke or can't hold a low position, 165-170 mm is worth testing.
- Re-set the saddle. Raise it by the crank difference (the helper above does the math), then re-check reach.
- Let your cadence rise. A shorter lever nudges cadence up — go with it instead of grinding the old gear.
- Only go as low as you can breathe. The opened hip angle is what makes a lower position sustainable — use it, but don't chase a position you can't hold.
What good looks like on video
The whole point of short cranks is a change you can see from the side: a more open hip at the top of the stroke, a flatter pelvis, and a torso that sits lower without the rider hunching or gasping. That's exactly what a side-view clip reveals — hip angle, back flatness, how the knee tracks at top dead centre. Film your position before and after a crank change and the difference stops being theoretical.
The bottom line
The pros didn't go short for leverage — they went short to open the hip, get lower, and keep breathing. The leg-power cost is small to none, the fit and aero upside is real, and the one thing you must not skip is re-setting your saddle. Change the crank, raise the saddle, use the room it gives you.
Sources
- Sports Biomechanics (crank-length kinematics) (2025). The impact of minor crank length adjustments on lower body cycling kinematics (Taylor & Francis, 10.1080/14763141.2025.2511755)Minor crank-length reductions significantly lowered peak knee flexion (up to 24%) and hip flexion (up to 13%).
- Effects of crank length on efficiency, sprint & fatigue (2025). Effects of crank length on cycling efficiency, sprint performance, and perceived fatigue in high-level amateur road cyclists (PMC12060448)Shorter cranks did not impair efficiency or sprint power and reduced perceived fatigue vs 175 mm.
- Bigham / Roadman Cycling (aero hierarchy) (2026). Dan Bigham Aerodynamics Guide for Amateur CyclistsThe rider's body is ~80% of aerodynamic drag; position changes save 10-20 W vs 2-4 W from an aero frame at amateur speeds.
- Burt, P. (reported) (2026). Shorter Cranks: 15 Watts FTP, Better Hip Angle, Faster Aero (Roadman Cycling)A switch to 165 mm cranks was reported to add ~15 W of FTP on average via better dead-zone passage and breathing.
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