Professional cyclists are increasingly adopting shorter crank arms—typically 160mm to 165mm—to improve hip angle and aerodynamics. According to equipment specifications from the Tour de France, riders like Tadej Pogačar and Jonas Vingegaard have transitioned to shorter cranks to reduce joint strain and lower their frontal profile during aggressive riding positions.
Why are pro cyclists switching to shorter cranks?
The shift toward shorter cranks is driven by biomechanics and aerodynamics rather than raw power output.
When a rider uses shorter cranks, the top of the pedal stroke is lower. This prevents the thigh from coming as close to the torso, which opens the hip angle. According to bike fit theory, this allows riders to maintain a deeper, more aerodynamic tuck without experiencing hip impingement or discomfort. For example, Tadej Pogačar transitioned from 170mm to 165mm arms, while Jonas Vingegaard utilizes 160mm SRAM Red crank arms on his Cervélo S5.
Do shorter cranks increase power or cadence?
Shorter cranks do not inherently increase power; in fact, they may produce slightly less torque than longer arms. However, they allow for a more efficient application of that power. Research cited in “Cycling with Short Crank Lengths Improved Economy in Novices” suggests that shorter arms can improve cycling economy by reducing the distance the foot travels during a full rotation.
For amateur riders, the impact on numbers is often negligible. Field tests show that average power and cadence typically remain stable after a switch. The primary gain is “feel”—specifically a smoother pedal stroke and the ability to remain seated longer during steep climbs due to reduced knee and hip strain.
What are the practical benefits for non-professionals?
While pros chase marginal gains, amateur cyclists can see three distinct advantages from shorter crank lengths:
- Joint Health: Reducing the diameter of the pedal circle minimizes the extreme flexion of the hip and knee, which can reduce long-term wear and acute pain.
- Ground Clearance: Shorter arms provide more space between the pedal and the pavement. This is critical for cornering at high speeds or riding over technical terrain in gravel and mountain biking, reducing the risk of “pedal strike.”
- Saddle Comfort: By reducing the vertical movement of the hips at the top of the stroke, shorter cranks can minimize the rocking motion that often leads to saddle sores and chafing.
Comparing Common Crank Lengths
| Feature | Long Cranks (172.5mm – 175mm) | Short Cranks (160mm – 165mm) |
|---|---|---|
| Leverage | Higher mechanical leverage/torque | Lower leverage; requires higher efficiency |
| Hip Angle | More closed (tighter) at top dead center | More open (relaxed) at top dead center |
| Aerodynamics | Higher frontal profile in aero tuck | Easier to maintain low, aggressive position |
| Clearance | Higher risk of pedal strike in turns | Increased ground clearance |
How to transition to shorter crank arms
Switching crank lengths requires more than just swapping a part; it necessitates a full bike fit adjustment. Because the pedal spindle sits closer to the bottom bracket, the rider’s leg will be more extended at the bottom of the stroke.
According to fitment guidelines, riders typically need to raise their saddle height to compensate for the shorter arm. For a 10mm reduction in crank length, a saddle increase of approximately 5mm is often the starting point, though this varies based on individual flexibility. Failure to adjust the saddle can lead to an inefficient power phase and potential knee injury.
Is the upgrade worth the cost?
For most riders, the decision depends on current comfort levels. If a cyclist is not experiencing hip or knee pain, the performance gains are likely too small to justify the expense of new components. High-end carbon options from Shimano or SRAM can cost several hundred dollars, especially when including power meter integration.
However, for those struggling with saddle sores or those who feel “cramped” in the drops, shorter cranks offer a mechanical solution to a biological problem. Experts recommend consulting a professional bike fitter before making the change to ensure the new geometry aligns with the rider’s specific anatomy.