Knee health and crank length.

[kevinalexandersmith]

Let’s set aside for a moment issues of speed and control. What is better for your knees long term?

Making small circles with straighter legs seems like it would put less strain on your knees. However, making larger circles would seem to have a range of motion benefit.

Anyone in the medical or therapeutic field able to comment in on this?


I don’t have any knee problems now, but I’ve started riding several miles daily for health. I’d hate to wind up having a knee replacement or something due to over exercise. Anyone with knee health experiences we can learn from.

[ezas]

I put short cranks but its not that simple. It's not so much the short crank it's how much pressure you are putting on the pedal and how your knee is tracking through the pedal stroke. In general a higher RPM with lighter pedal pressure is going to be better than mashing long cranks. Also a higher seat is going to put the knee through less range of motion, engage more leg muscles and in that way help your knee.

But its much more about how your knee is tracking through the range of motion you are putting it through.

For road work, I think more important than crank length is seat height. As I have said a few times in these pages a low seat height does not engage the vastus medialis. In a vast over simplification the outer quad become stronger than the inner quad and your knee cap is pulled to the outside and next thing you know you have what goes by the common name 'runners knee' the most common knee overuse injury. But its not as simple as one muscle being tighter than another. Many factors combine to cause knee pain or not cause knee pain. Some people are blessed with better natural alignment and can get away with things that would bother others.

Other factors are x-training. Someone who does more than unicycle is going to tend to develop fewer overuse injuries because they work a wider range of muscles and use them in different ways.

In a very simple example of this. I live on a steep hill. Walking up that hill bothers my knee. Walking backwards both up and down the hill (especially up) makes my knee feel better. It makes sense, in walking up the hill I am doing an action very similar to pushing down a pedal. In walking backwards up or down I'm picking my leg up or pushing away in the opposite direction of pedaling.

I recommend reading about 'runners knee' and 'jumpers knee'. Those will give you a good start towards understanding knee health.

At 36 you are smart to head off knee problems now rather than try to fix them like I am doing. I thought a month of exercises and stretches and I would be good as new. Nope im going on about 3 months and I am just now being able to add idling practice back in to my riding. I can ride flat distances now with no problem but add one hill to my ride and my knees let me know about it later.

[AlisterBurt]

I like turtle's V frame
As said above, my knees used to hurt alot when I rode with my seat low, my back too. now that it's higher its much less of a problem.
(trials riding though, not road)

[wumpus]

my knees are hurting, but it seems to me less from crank lenght, more from the wobble/misalignment when I pedal while Muni-ing during steep DH sections. The first bouts occurring during the last mile on a long 12 mile sherando lake muni ride, lots of DH. Going to play more with seat height, but I find that resisting the wheel on steep DH sections led to more wobble as one foot then the other is predominately providing the resiting force to the spinning wheel. Brakes may help.

[kevinalexandersmith]

Originally Posted by ezas

lighter pedal pressure is going to be better than mashing long cranks.

With the benifit of more leverage, wouldn't longer cranks mean lighter pressure as opposed to mashing on shorter cranks?

Did you mean one thing but type another or do I misunderstand?

[SmellyGeekBoy]

My knees hurt less with longer cranks, even with "harder" riding. I use my dual hole cranks on both settings (125 and 150) as often as I can. Not for health reasons, just because I like to do a range of different riding styles.

I voted "I like turtles" because I'm no doctor and I don't have a clue

[MatthPeder]

You also have to consider the type of style a person is riding. If someone is riding trials, they could have knee problems from jumping. This can also depend on height, weight and what kind of tire you have (ex. trials tire vs. freestyle). In all styles, knees can have problems so it's hard to say what length is better (also remembering some cranks are better for different styles) than the other. I bet I just wrote one thing that is completely wrong and stupid, but, hey, I'm not a doctor.

[kevinalexandersmith]

It sounds like more people think short cranks are better for your knees, but I haven't really be getting why.

You make the same number of revolutions either way, but you have to push harder on shorter cranks and they provide less range of motion.

I still feel pretty lost and confused on the subject.

[saskatchewanian]

When my knees start to hurt i switch to longer cranks, not because I think they are better for my knees but because longer cranks are easier to use when you are hurting/weak/tired.

When I used to ride a relatively small wheel with short cranks (27" with 102mm) I did not have knee problems but did shorten my ham string which came up when I finally went for a run instead of a ride. After that I started running as well as riding regularly to keep my legs balanced and eventually over developed part of my quads which pulled my kneecaps out of alignment.

Next time I train for a uni event I will have to add swimming to the running a cycling, who knows I might just want to do a triathlon after


yah I guess I did not really answer the question. I think it has more to do with technique and riding style than crank length.