CoachingAnswer

SHOULD I SWITCH TO SHORTER CRANKS?

By Anthony WalshRoadman CyclingUpdated 26 May 2026

ANSWER

For most amateur cyclists — particularly those under 5'10", with limited hip flexion, or dealing with knee or hip pain — switching to cranks 5–10mm shorter than standard 172.5mm is worth considering. The evidence for significant power loss is weak; the evidence for reduced knee pain and improved hip clearance is real. Many riders gain 10–20 watts simply by being able to push harder without hip impingement limiting their position.

KEY TAKEAWAYS

Standard 172.5mm cranks are too long for many cyclists — particularly those with limited hip flexion.
Shorter cranks (165–170mm) reduce hip impingement at the top of the pedal stroke and often relieve knee and hip pain.
Power loss from shorter cranks is minimal — typically under 1% — and is frequently offset by better position and reduced pain.
Riders who gain most: those under 5'10", with knee or hip pain, or who've been told their saddle needs to be unusually high.

WHO THIS IS FOR

IS THIS YOU?

The rider with hip pinching or knee pain

You feel a catch or impingement at the top of the pedal stroke, especially when out of the saddle or at higher power.

The rider whose position never feels quite right

You've had multiple fits without fully resolving discomfort — crank length may be the missing variable.

THE ROADMAN VIEW

Shorter cranks are one of those marginal gains that aren't marginal at all for the right rider. Anthony covered this with an episode where the message was direct: most cyclists are on 172.5mm cranks because that's what was specced on their bike, not because it's right for their anatomy. And for a rider who's 5'7" with normal hip flexibility, 172.5mm cranks are almost certainly creating impingement at the top of every pedal stroke.

The impingement matters because it limits how low your front end can be. When your hip is cramped at the top of the stroke, your body compensates by either rocking the pelvis or reducing hip flexion — which means you can't get as aero or as powerful as a better-fitting crank would allow. Fix the crank length and suddenly the fit makes sense in a way it didn't before.

The power question gets asked every time. People assume that shorter cranks mean less leverage and less power. The research doesn't support this at cycling-relevant crank length differences of 5–10mm. A crank 10mm shorter doesn't reduce power — it reduces impingement and often allows higher cadences, a more comfortable position, and the ability to push harder for longer without restriction.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Phil BurtFormer Team Sky and British Cycling physiotherapist and bike fitter
Crank length is the most commonly overlooked variable in bike fitting. Many cases of knee pain, hip impingement, and persistent position problems that don't respond to other fit changes resolve when crank length is corrected. For riders under 5'10", 165–170mm is often more appropriate than the industry-standard 172.5mm.
Hear it: 5 Bike Fit Mistakes | Roadman Cycling Podcast
Shorter cranks self-experimentRoadman Cycling
After switching from 172.5mm to 165mm cranks, a noticeable improvement in hip clearance at the top of the stroke allowed a lower, more aero position without any hip discomfort. Power numbers held steady; the position became sustainable for longer without the restriction that had previously limited efforts on climbs.
Hear it: How I Gained 20 Watts Using Shorter Cranks (No Joke)

PRACTICAL APPLICATION

DO THIS WEEK

Check for hip impingement at the top of the stroke
Clip in and pedal at normal cadence. At the top of the stroke (12 o'clock position), notice whether you feel any pinching, catching or restriction in the hip. If yes, and especially if this is worse at higher power or out of the saddle, crank length is a strong candidate. Film yourself from the side in slow motion to see if the pelvis rocks at the top of the stroke.
Try 165mm or 170mm cranks if you're 5'10" or under
Most riders under 5'10" (178cm) are well-served by 165–170mm cranks. If your current cranks are 172.5mm or 175mm, a switch to 170mm is a conservative first step. Many cyclists who move to 165mm for the first time report that it feels immediately more natural at high cadences and less restricted on climbs.
Readjust saddle height after changing cranks
Shorter cranks reduce the effective leg extension at the bottom of the stroke. After fitting shorter cranks, raise the saddle by roughly half the crank length reduction — so 5mm shorter cranks needs approximately 2–3mm more saddle height. Then recheck knee angle and fine-tune from there.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEAssuming standard 172.5mm cranks are correct because they came with the bike.
FIXCrank length is specced for a generic average, not your anatomy. Check whether you actually have impingement before assuming the standard length is right for you.
MISTAKEExpecting an immediate power boost from shorter cranks.
FIXShorter cranks usually provide neutral power in the short term. The gains come from position improvement, reduced pain, and the ability to sustain higher effort for longer — not from an instant watt increase.
MISTAKEForgetting to readjust saddle height after changing cranks.
FIXA change in crank length changes effective leg extension. Always recalibrate saddle height after a crank change — failure to do so introduces the same position errors you were trying to fix.

FAQ

FREQUENTLY ASKED QUESTIONS

Will shorter cranks make me slower?

Unlikely. Research on crank length differences of 5–10mm shows negligible power differences in trained cyclists. The theoretical leverage loss is smaller than the practical gains from improved position, reduced impingement, and better hip clearance for most riders.

What crank length should I use?

A rough guide: riders under 5'6" (168cm) — 165mm. Between 5'6" and 5'10" (178cm) — 167.5–170mm. Over 5'10" — 170–172.5mm. These are starting points; a professional fit using hip mobility assessment gives a more accurate prescription.

Do shorter cranks help with climbing?

For riders with hip impingement, yes — significantly. Climbing at high power out of the saddle amplifies any restriction at the top of the pedal stroke. Remove that restriction and you can apply more force through the stroke without fighting your hip. Many riders report climbing feeling materially easier after a crank length change.

Are shorter cranks better for high cadence?

Generally yes. Shorter cranks reduce the angular velocity demand on the hip at high cadences, making it easier to spin at 90–100rpm without feeling like the leg is being driven up too fast at the top of the stroke. Riders transitioning from 80rpm to higher cadences often find shorter cranks help.

How much do replacement cranks cost?

OEM crank replacement varies widely. Aftermarket single-leg solutions from brands like Rotor, Shimano, and SRAM range from £150–£600 depending on specification. It's worth getting a fit assessment first to confirm the right length before spending.

RELATED EPISODES

HEAR THE CONVERSATIONS

How I Gained 20 Watts Using Shorter Cranks (No Joke)

5 Bike Fit Mistakes | Roadman Cycling Podcast

The Correct Bike Fit Simplified | Dr Pruitt