Are your cranks the right length?
A group of friends and I rode to the Los Angeles National Cemetary on Veterans Days and I noticed that one of our group seemed to be spinning very fast. He’s very tall and I remarked that he might benefit from longer crank arms. Full disclosure, I know just a bit about bicycle fitting but I’m by no means a sports physiologist.
Today, as I was having my morning coffee and clearing my email inbox, up came Stu Bowers article in Cyclist on crank arm length. Stu’s lead-in paragraph caught my attention:
“It’s possible a good number of people reading this don’t know what length cranks are fitted to their bike. Many might not even be aware that they come in different lengths. Yet cranks affect how effectively we generate pedalling force, as well as our overall comfort on the bike, so shouldn’t we be paying more attention?”
I think my time trial bike crank arms are too long
What really caught my attention was his point about how a crank arm that is too long can inhibit breathing in a low aero position and cause problems for the hip flexors and hip extensors.
‘Crank length can influence a number of things. In a low, aero position the hip joint angle becomes very closed, which makes breathing harder; hip flexors become tighter and the hip extensors [glutes] spend longer waiting to engage.’
I’m 5′ 9″ and I have 175 mm crank arms on my time trial bike. I’m getting a bit older and getting into a low aero position has been increasingly uncomfortable. This should have dawned on me without the article because I have 165mm crank arms on Serenity track bike both for sprints and time trials.
Time for Change
‘I would say at least half of your readers aren’t as aero as they could be because their cranks are too long,’ says Martin.
‘Anyone in the range from 5ft 8in to 5ft 10in won’t be able to get a horizontal body position with standard length [170-175mm] cranks. It will typically be worse for women, who are shorter on average, not to mention anyone a bit older, who will almost certainly have reduced range of movement in their hips.’
My next step? I’m going to reach out to my long-time mechanic, Les Welch, at East Coast Bicycle Academy in Harrisonburg, Virginia for a 165mm setup for Zonker (my time trial bike).
Read the full article here . . . Training points: Are your cranks the right length?