Thanks for all the problematisation around crank length. I've never thought much about myself as I've, like most people, rode what was available. I started looking around and it appears that there's a bit of research (that reiterates much of what's been said so far). My discipline isn't biomechanics, but I thought I'd share it anyway as it's pretty interesting (I know it's not a lit review, just a quick look).
Bouman (2021) found that shorter riders (that is people on bikes that are in smaller than 55cm) tend to be underserved when it comes to cranklength: - *Industry Standard Crankarm Length (CL):* Most cyclists ride with a standard crankarm length of 165–175 mm, regardless of their bike frame size. - *Potential Mismatch for Small/Medium Riders:* Riders on smaller frames (<55 cm) may have CLs longer than optimal (>20% of inseam), which could affect comfort and performance. - *Impact on Joint Angles:* A standard CL can increase knee and hip flexion angles for shorter riders, potentially affecting comfort and force production. - *Power Production & Efficiency:* Optimal crank length for power production is around 20% of inseam length, but most shorter riders use crankarms that are longer than optimal. Ferrer-Rocha (2017) found that - Longer cranks led to *more force but less efficiency*. - Also, when in doubt as to crank length, since shorter cranks produce less range of motion and thus less flexion in the knee, they're probably less likely to produce discomfort and/or pain. As it turns out, there's even literature on set back on saddles and comfort! *Refs* Bouman, M. J. (2021). *The Relationship Between a Road Cyclist's Bike Frame Size and Riding Comfort, Pain, Frequency, and Duration*. California State University, Long Beach. Ferrer-Roca, V., Rivero-Palomo, V., Ogueta-Alday, A., Rodríguez-Marroyo, J. A., & García-López, J. (2017). Acute effects of small changes in crank length on gross efficiency and pedalling technique during submaximal cycling. *Journal of sports sciences*, *35*(14), 1328-1335. On Saturday, March 1, 2025 at 8:48:35 AM UTC+1 Nick Payne wrote: > On Thursday, 27 February 2025 at 12:33:18 am UTC+11 Garth wrote: > > I suspect many people would like the feel of short cranks regardless of > the bodily measurements. I'm talking about say 140-155mm. > > > A blind experiment: my wife, who is only 5'2", is an experienced cyclist, > and has been riding on 160mm or 165mm cranks for over 40 years. She's > always used quite a high cadence, and on the most recent bike I built up > for her, I installed a pair of the 152mm Sugino XD cranks. I set the saddle > height so that at the bottom of the pedal stroke she had the same leg > extension as on her other bikes, but I didn't tell her that the cranks were > shorter. > > She didn't make any comment about the cranks feeling shorter, but said, > after three or four 40-50km rides on the bike, that she really liked > pedalling that bike. I then told her that I had fitted shorter cranks, and > she has now asked that I also fit shorter cranks to the other couple of > bikes on which she does most of her riding. > > Nick Payne > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/24339be0-473e-4a8d-89c1-391782e9cd82n%40googlegroups.com.
