Longer or shorter? Does it really make a difference?
I have been cycling for over 23 years and have raced and trained with crank lengths ranging from 165mm in length on the track to 177.5mm on the road.
When I raced in France in the 90s, the trend was to use longer cranks. We saw relatively short cyclists like Hinault and Lemond using 175mm cranks. Mark Madiot won Paris Roubaix twice using a massive 180mm crank length. In Italy shorter cranks were in fashion. The tall Franco Chioccioli won the Giro on 170mm and Michele Bartoli, the great classic rider, raced 170mm cranks throughout his career.
In the early 90s I was fitted by the same bike fitters who set-up Lemond, Hinault and Indurain. They recommended I ride 177.5mm cranks. I tried them the following season but never felt efficient with such a long crank.
In recent years I have noticed a trend among some cycling experts to recommend shorter cranks. I personally now prefer a shorter crank of 172.5mm in length even though I am 6’1” tall.
In a recent webinar I attended with Andy Coggan, he presented scientific data showing that big changes in crank length did not significantly change performance. He also went on to say that the optimal length for most cyclists is probably under 170mm in length.
3 ways to determine your ideal crank length -
1) Your Height and Leg Length
A 170mm crank length for a shorter cyclist may feel the same as a 175mm crank for a taller cyclist with a longer leg length. Therefore, shorter cyclists usually feel more efficient riding shorter cranks compared to taller cyclists who often prefer a slightly longer crank. This may not always be the case however, as sometimes we see shorter cyclists who are able to spin longer cranks very efficiently. Some examples of this are Fabian Cancellara spinning 177.5mm cranks at a very cadence and Lance Armstrong spinning 175mm at 110rpm+ like a machine.
2) The Type of Cycling
For cycling that requires lots of accelerations, sprinting, and high cadence riding, a shorter crank is better. For most cyclists this will be between 170-172.5mm. For longer road riding with lots of hills, mtn biking where you need good leverage at a low cadence, and time trials (depending how extreme your position is), a longer crank length of 175-177.5mm is usually better. If your time trial position is very low then a shorter crank will give you less resistance at the top of the stroke and may work better.
3) Power & Feel
In my experience, your best crank length is the length of crank where you produce your best power while feeling very smooth, relaxed, and circular in your pedal stroke. This crank length will vary depending on the cadence requirements for the type of cycling you are doing (see #2).
Possible Signs that a shorter crank will work better for you –
- Feeling resistance at the top of the pedal stroke
- Feeling like you your pedal stroke is choppy (not circular) at a higher cadence
- Experiencing pain in the front of your knees
- Lower back pain
Even though a correct bike fit is more important than having your optimal crank length, it is still good to be aware of the subtle difference crank length can make to your performance and pedaling efficiency.