165, 170 and 175 mm cranks gave identical economy and 6-second sprint power in 28 trained cyclists; perceived exertion was lower on 165 and 170 than on 175 mm, a single imperfectly blinded result
Key Findings
Cycling economy and 6-second sprint power did not differ between 165, 170 and 175 mm cranks (13.23, 13.17 and 13.18 W/kg); perceived exertion was lower on 165 and 170 than on 175 mm.
28 trained male cyclists (VO2max 59.39 ± 5.75 mL/kg/min); 20 minutes at 60% of VO2max and a seated 6-second sprint on each of 165, 170 and 175 mm.
No differences in cycling economy, heart rate or sprint power (p > 0.34); 6-second peak power 13.23, 13.17 and 13.18 W/kg.
Perceived exertion at 60% VO2max: 3.21 ± 0.88, 3.46 ± 0.69 and 4.50 ± 0.69 — 165 and 170 mm lower than 175 mm (p < 0.001); 165 vs 170 mm not different.
Practical Application
Between 165 and 175 mm a rider gives up nothing in power or economy by going shorter.
The comfort signal — easier at the same output on the shorter cranks — is one study in which riders could feel which crank they were on. Offer it as "may feel easier", never as established.
Limitations
Pilot; men only; 20 minutes at low intensity; no long-event, climbing or injury data exist in any study found.
The abstract's phrase about reducing injury risk is not backed by a measured outcome. Full text was read.