Originally Posted by ESTrainSmart

I wasn't too interested in crank length until I corrected it and experienced an immediate 20-30 bpm drop in heart rate for the same speed. My pedaling technique instantly restored back to normal as well. In terms of power, there are reports of 100 watt improvements just from correcting crank length. The improvements I experienced were nothing short of massive.

The reason why I was in this situation in the first place was because I was forced to ride a completely new bike for 2014 when the tire casing of my new Conti GP4000S failed instantly after a sprint which totaled my previous bike. The new bike had a longer crank arm. I spent the full 2014 racing season unaware that my cranks were too long, but aware of major differences in my pedaling technique, cadence and heart rate.

I immediately blamed myself for the drop in performance because I didn't want to be "that person" who blamed the bike. I implemented various neuromuscular, mobility, flexibility, power lifting and strength conditioning protocols to combat the symptoms I experienced, but never saw any meaningful improvements. Changing the crank arm length instantly solved every problem I had tried to fix all year.

Sorry about that long background. I'm super passionate about this topic because of how much it affected my performance. I'm presenting my crank arm length test to a few research boards to have it studied for its accuracy.

Anyway back to your questions! When the cranks are too long, it causes the hip, knee and ankle to reach its optimal range of motion for power production too early. As a result, the rider will never feel like he or she is using their full potential throughout the power phase, especially with explosive efforts. Using a piston in an engine as an example- it's similar to the spark plug firing before the piston reaches the top. The stretch coming from either the pelvic wall, core, hip, knee or ankle musculature adds extra resistance to each pedal stroke through a co-contraction. It's like holding an active stretch repeatedly.

In terms of sprinting with long cranks, being on the drops will make things worse. A rider with long cranks will naturally favor a higher position with the hands on the hoods. If the rider forces the hands on the drops, the hips will shift forward towards the handlebars which will drastically reduce gluteus maximus activation. The reduced glute activation leads to a significant drop in power.