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I went from 172.5 to 165mm. I am 5'11 with a 32" inseam. Due to arthritis in my right hip, I shortened my crank length because of pain in my hip on the up stoke while pedaling. After doing so, I saw an increase in speed, due to the lack of pain!!...so, yes crank length does matter! Bottom line, everyone is different, so find what works for you! Smooth is fast!!!

From 172.5 down to 165 on my TT bike and i'm 6f1inch (185.4cm). Theres's a huge diference on my position on the TT bike and my cadence is up... I like it!! On my computrainer I still put the same power (ftp) but I'm more aero and stay easy at 95-97 rpm for a long period... really better for me. I hope this will help some who are hesitant at least for TT bike. (excuse my english, I'm french speaking)

Nice work on a tough subject, I'm an older rider and I discovered a few years ago that I have less knee pain with shorter cranks, even when bike fit is adjusted.

Crank length is important. As a keen cross country unicyclist, I find choice of crank length is vital. Shorter means I can spin faster but with less leverage; longer gives me more leverage for hills, but a slower cadence. A unicycle is direct drive (fixed gear) so crank length and wheel diameter are the main two variables, and crank length is the easier one to change. However, with very short cranks, you use a smaller part of your range of muscle contraction, and with very long cranks, you move the mass of your legs further. On a bicycle, you are able to choose the gear ratio between the chain ring and the rear wheel. Therefore, it makes sense to choose the crank length solely for what gives you the best, most comfortable and most efficient pedalling action. About 170 mm for a typical adult male, a bit shorter for someone who is shorter, and possibly a bit longer for someone who is very tall. Think of the legs/cranks as the engine. Optimise the engine, then use the gears to direct that power to the rear wheel.

Thanks, easy to understand. Thanks Angus below as well. I've got a similar problem at age 72. Might try the shorter cranks and keep on pedaling.

It also depends on the type of use or discipline of biking you do. Most MTBers go for longer cranks and the reasons are obvious. You need more torque and the longer arm helps in that. Plus in many instances, you don't really need to spin as fast.

Here goes something no body has heard, train on bike with smaller cranks to improve speed, then when you race go with the longer cranks to generate peak power

Cycling Bio-mechanics equals muscular considerations (bio) and non muscular(mechanical) considerations.

This is a great idea and you should really do this video again, it is certainly worth while! You acknowledge the confusion between Cadence and Pedal speed in the notes you added, but it is not clear when you are using the right terminology and when you are not (thus I suggest a redo!)

Thanks for a great explanation

The main benefit of a longer crank (longer end of "normal" range) is when "jumping" in to an acceleration. IOW, when operating at peak torque. This is rare for most athletes. And it's a compromise because you might be losing top end (high cadence) power development. Study power and torque curves of internal combustion engines to understand the torque/power dynamics and then remember that with your own "engine" you risk over-stressing your muscles - an additional risk.

You explain things very well. Thanks.

11:30

Best explanation yet on crank length. 5 stars! Seems awash in the middle ranges of crank length as the multitude of gear choices dominates most rides anyway. Thanks!

Started riding 12 years ago with 175's. I am 5'9".s 31.5 inseam. Use 170's now and could no the happier. 53 x 39

This is Wilson X Bezerra. You are right if you are talking about the conventional bicycle but not our stepper bicycle. The convention bicycle will become obsolete within the next few years. Our 20 year patent has been approved and we are sec approved. Our crankarm is 20 inches long. We operate in the most efficient area of the circle when pedaling, 2 to 4 o’clock. The forces on the conventional bicycle goes into the frame ours goes into the wheel. No distortion of the frame or fork. Also, we use 2 of the strongest muscles to propel the stepper bicycle forward instead of 8. We eliminate muscle fatigue while riding. The chain always remain straight when shifting. Our pedals are directly on top of the crankarm and not on the side. This avoids jerking the frame from side to side. Our RPM exceeds 120. Even though all can ride our system, it also allows a person missing a limb or those who have mobility issues to ride. Please visit our website.

All this are fairly important to me. I have to race my neighbour to the market and see who get the freshest fish every day.

I have used cranks between 165 mm and 175 mm. I found that in effect the main advantage of a longer crank was in hill-climbing.

Super happy with my upgrade to 180mm