Posted by Clive de Sousa on 6th Aug 2016

Crank Length - Bigger Is Not Always Better

We often get fit questions from customers. One of the most common queries is crank length. Looking at pros’ crank lengths we’re tempted to emulate our heroes. I remember using 180mm cranks because I saw five time Tour de France winner Miguel Indurain destroy the competition using that same length. Recent Tour winner Chris Froome uses 175mm as he stormed to victory.

However, we need to remember we’re not World Tour riders and shouldn’t use a long crank just to be like Froome. In fact the tide is starting to turn on the myth that long cranks give better leverage therefore a rider is able to push a bigger gear at less physiological effort. Science has proven that to be wrong.

In the Journal of Sports Science a study was done to test the effects of different crank length. Using 12 amateur cyclists they discovered that there was no difference in the rider’s heart rate or gross efficiency when using longer cranks versus shorter cranks. The abstract closes by saying, “in case of doubt between two lengths, the shorter one might be recommended.”

Also, using shorter cranks allows you to drop your chest a little lower, opening the hip angle to become more aerodynamic without the knees punching you in the chest. And let’s take a moment to be honest and self reflective: how flexible are you and could you spare to lose a couple of pounds around the midsection?

The reality is that most of us aren’t that flexible in the hamstrings and quadriceps, so a longer crank would stretch those muscles and put additional strain on those groups. If you’re suffering with some lower back pain, shorter cranks might be the way to take strain off the back. Also, with a bit of additional belly fat, the knees at the top of the pedal stroke is impeded as it hits your gut. And who wants to ride with your knees hitting your stomach with every pedal stroke?

So while Froome and some others are grinding out the rpms on long cranks, remember you aren’t them. In fact, several Team Sky riders have been using cranks as short as 170mm. Who knows, maybe next year we’ll see Froome switching it up to 172.5mm cranks?

Sources

Journal of Sports Science: http://www.tandfonline.com/doi/abs/10.1080/02640414.2016.1215490?platform=hootsuite&journalCode=rjsp20&

Cycling Weekly: http://www.cyclingweekly.co.uk/news/product-news/...