Question: Standard theory says that most riders should use crankarms of 170, 172.5 or 175 mm. I’m 6-foot-6 and use 196-mm cranks from Roger Durham at Bullseye. (My frame has a raised bottom bracket for clearance and a steeper seat tube.) I can’t say I’m a dramatically better cyclist using the 196s compared to 180s. What’s the current thinking on long cranks for tall people? — Damien R.
Coach Fred Matheny Replies: Crankarm length is one of the most confusing issues in cycling.
Lennard Zinn wrote an article in VeloNews several years ago detailing his attempt to study the issue, and there have been numerous other studies, including Ronald Pfeiffer’s at Boise State University. None has shown any definitive correlation between leg length and crankarm length. Essentially, riders are most efficient on the crank length they’re accustomed to using.
Though there’s a more recent thread that says shorter is better.
There may be other factors at work, too, like muscle fiber type. Maybe people high in fast-twitch fibers (who have more explosive strength) are better off with shorter cranks that they can spin. Conversely, slow-twitch endurance athletes can push larger gears at a moderate cadence and are aided by longer cranks. But there are so many exceptions to this idea that it seems to hold little water in the real world.
I suspect that riders of your height need longer crankarms, but maybe the 180s commonly available are a better choice simply because they don’t require a modified frame.
When all is said and done, you’ll probably do best on the length you’re accustomed to and believe in. That’s not very scientific but, so far, science hasn’t been particularly helpful on this issue.
Coach Fred Matheny is an RBR co-founder who has four decades of road cycling and coaching experience. He has written 14 eBooks and eArticles on cycling training, available in RBR’s eBookstore at Coach Fred Matheny, including the classic Complete Book of Road Bike Training, which includes 4 eBooks comprising 250 pages of timeless, detailed advice and training plans. The Complete Book is one of the many perks of an RBR Premium Membership. Click to read Fred’s full bio.