Knee Pain and Crank Size?

Unicycles and Equipment
1

Hi all,

I’ve been unicycling for a couple of months now, and have recently begun to experience knee pain. It is the very same that is popular with many other unicyclists–the one that is especially painful when trying to stand up or going up the stairs.

From a few of the other threads I’ve found on here, the general recommendation is to lay off unicycling until the pain subsides, do some muscle exercises, and/or see a chiropractor/physician. I am currently doing these things.

But my question is whether crank arm length affects knee pain. I am currently using 165mm on a muni. Needless to say, my legs are bouncing all over the place when I try to ride fast. I am also thinking that maybe the extra wobbling caused by longer cranks are putting extra stress on my knees. Are there any credence to my theories, or are knee pains and crank lengths totally unrelated?

Has anyone here actually had personal experiences where going to a shorter crank size (i.e. 125mm) helped reduce knee pain?

Thanks for the response,
D. Y.

2

Simple answer. Yes.

Knee problems on unicycles is generally caused by rotational and lateral movement at the joint. The long cranks causes the wheel to twist more at every pedal stroke and hence more pain at the knees.

Roger

3

I havent experienced any adverse problems yet from any uni riding.
If any time i find riding not very comfortable or any soreness other than riding outside my fitness level i change something until things feel better.
I cant comfortably ride more than 150mm. 137 is my chosen muni crank for speed and toque. Its the size i find comfortable on me and suits the terrain most of the time.
Consider a brake for the declines if you dont have one this can save alot of pressures on knees once used to using one. Seat height also people might mention needs to be correct for you otherwise problems may arise eventually.
Hope all goes well. If the soreness lingers acupuncture can (does) help also in far more ways than general exercises and practitioners can provide.
Unicycling is a great sport. I dont like hearing some of us are suffering because of we do so much of the sport we love. Dont be discouraged or give it up. Or aggravate the ailment for that matter!
All the best

4

The 165mm cranks will cause your knee to bend more at the top of the crank rotation thus putting more pressure on your knees. 125mm cranks are ideal for a learner on a 20" wheel, but I think that you are riding a 24" wheel, in which case I would suggest you use 137mm/150mm cranks. You could also try shortening your uni sessions and taking rest intervals during each session.

Hope this helps.

5

This is an interesting issue for me. I’ve had arthroscopic surgery on both knees (to repair a torn medial meniscus in both cases. The repair consisted of removing about 20-25% of the MM).

So, fairly recently I started experiencing knee pain again and even some swelling. I figured I was going to have to go under the knife again. Coincidentally, I suddenly found myself able to afford a g36, and I bought one, hoping that I could maybe ride it a bit. I also bought myself a scooter because I figured it would mean a bit of an ease-up on my knee when I had to walk any considerable distance. I never rode more than 4 miles in a day.

As for the g36, I mainly ride it geared up, and it has 150s.

Once I got the uni, I noticed that my knee started feeling better the very next day, which made no sense. So I decided to put it to the test. I rode even more the next day and the next. My knee felt better each time.

A few days after I’d gotten my g36, I rode a marathon, and by then, I had no knee pain at all. I was also doing a little scootering at this time – maybe 2-3 miles a day – but that ended four days ago. In that time, I rode 27, 30, 36, and (last night) 44 miles on the g36.

My knees feel great. The only twinge I get is in my left knee when I’m trying to change gears and the uni slips a bit. Other than that momentary ouch, I’m fine on and off the unicycle.

I should do some other leg-strengthening exercises, but I haven’t started them yet. I don’t do any other exercise.

6

A unicycle is unique, unlike a bicycle where you can change gears, coast, and rest your legs, unicyclists are forced to use their legs to stop, balance, and pedal in time with their wheel speed.

First off, knee pain comes from over use, whether from pedaling too much, pedaling too hard, having too much knee angle, whatever your problem it is still from over use even if it is misuse :roll_eyes:

Since you are already doing physical “rehab”, which I assume includes stretching and cross training, lets focus on the mechanical side of the work your legs are doing.

There are a number of ways to reduce the work your legs/knees are doing:

Shorten the cranks (reduce knee angle)
Ride a larger wheel (reduced rotations/cadence)
Ride Slower (reduced speed of rotation/cadence)
Ride easier terrain (obviously this will be easier on your legs)
Lengthen your legs by raising the seat (improved efficiency/reduce knee angle)

For each of these changes there is a downside:
Shorten the cranks = less leverage for climbing, braking, and control
Ride a larger wheel = requires more effort to start, stop, and maintain momentum
Ride Slower or easier terrain = Not as fun…
Lengthen your legs by raising the seat = less seat clearance for out of seat climbing and obstacle negotiation (muni)

Also consider the possibility that you are exceeding your body’s ability to recover and or your not yet in shape to ride as you would like to ride. In my experience, when you embark on a new sport, esp one that requires a new set of muscle development, it takes years to develop muscle and bone structure to support the demands of that use, esp if you are trying to do that sport at your limits.

Also, because unicycling requires the user to maintain balance at the same time they are maintaining propulsion, experience and time in the seat can make a huge difference as to your efficency and endurance. So the better you are at riding, the less work you do when riding.

I have played with crank lengths, shorter did not help my knee pain, in fact my knees hurt more because I was working harder on climbs and descents. As a result I tend to run longer cranks (165s) when I am going to be doing extreme ups and downs, then shorter cranks when I am going to be doing more flats. I also use brakes which take the pressure off my legs on downhills.

=> And after all my long winded verbage, this single comment is what catches my eye:

You need to look at the most obvious issue: You are a new rider, you have not developed the balance and physical structures to support this activity, as a result you are suffering from overuse.

Shorter cranks will not replace experience.

Ride easier terrain, emphasize time on the seat, give yourself a rest day (or two) between rides, use NSAIDs, get a brake if you do downhills.

7

Just adding my 2 cents to the topic:

I have noticed some knee pain on one if my knee only a while ago. Turned out that it matched the moment I switched my 29er to 100mm Qu-ax cranks. Seems like the reduced torque of the short cranks increased the stress on my knees when riding a downhill road (no brakes installed on the uni). I wasn’t sure either if the straight cranks (no Q factor) did not add another position issue.

In comparison, I can ride hard and for a couple of hours off-road with 150mm KH cranks on a 26 or 29 without a glimpse of a pain.

I decided then to go back to longer cranks for road use (125mm KH) and even though it is not as efficient as the shorter ones, I don’t feel like I am blowing my knee down a hill.

I am having brakes installation in my todo list to see if it helps even more :wink:

8

This has come up on threads here in the past- posts on those seemed to indicate that there’s certainly no consensus on whether short cranks or long ones are the cause/cure for knee pains.

i.e. some riders have found shorter cranks help, others have found longer ones do.

Certainly, shorter cranks = less leg and knee movement, so if your knee pain is caused by excess movement, going shorter might help.

Equally though, longer cranks = greater leverage, so less force on the knees when climbing, and, especially, when descending hills: so, if the knee pain is caused by too much force, longer cranks may help.

I’d suggest trying different lengths of crank and seeing which length gives least knee pain might be worth trying.

9

That’s interesting- recently I had a similar experience: I’d got a new bike and for a few weeks rode mainly the bike rather than unicycling. My knees started to give me a few twinges, both when riding and walking.

So I switched back to the unicycle and very quickly the knee issues dissapeared.

My hypothesis at the time was that, as unicycling involves backwards pressure on the pedals (e.g. when going down hills etc), whereas bicycling only has the forwards pressure, due to the freewheel; that a bike might develop the front/back leg muscles unevenly, whereas unicycling does both.

I know that many fixed gear cyclists say the same thing- that a fixed gear bike is better for the knees than a standard freewheel equiped bike.

10

I think everyone is different, so what works for one my not work for another, or may make it worse. That being said:

  1. I found offset cranks hurt my knees (mainly during turns). Straight cranks feel better.
  2. I wear snug-fitting knee pads (normally worn by wrestlers). They not only help protect my knees from falls, but they provide support that makes my knees feel better.
    That’s all I have to say about knees pain.
11

Thanks everyone for all your input. The unicycle i own is in fact a 24" muni. I’ve already purchased a set of 125mm cranks, so will get back to you when they arrive and once I’ve tried them. Of course, if anyone else think of anything more to say on the subject, please don’t hesitate.

D. Y.

12

[QUOTE=LanceB;1594010]

  1. I wear snug-fitting knee pads (normally worn by wrestlers). They not only help protect my knees from falls, but they provide support that makes my knees feel better.
13

[quote=“unibokk,post:12,topic:120974”]

Hello Lance, I also wear knee supports. I use elasticated weight lifting knee supports. I feel that they help keep my knees in line and that they help prevent hyper extension of the knee and I’m happy to say that my knees are in good shape. I don’t recommend them as a cure for knee problems as I think that if someone is having trouble with their knees then they need to first find out what’s causing it and get it sorted.But I do recommend the supports for preventing knee problems. But as you say, what works for one person may not work for another. I’d like to hear more opinions on this from other people out there. Maybe I’ll start a new thread.

And now I’m gonna have a beer and watch unigeezer’s new video.

14

These are the ones I use:
http://www.dickssportinggoods.com/product/index.jsp?productId=4301396&lmdn=Brand
I originally got them because I wanted to wear them under my trousers (didn’t care for the bulky strap-on types). I didn’t realize they were neoprene based – they’re like short sections of a wetsuit. So they make your leg sweat under them, but they are tight enough to provide a nice support, while not being restrictive. (Someone also mentioned that the extra heat generated around the area might help the joint.) I wasn’t expecting them to make my knees feel better from using them, but that’s what happened. A nice side benefit.
As mentioned above, this might not be a good solution for everyone, but it works for me. Nice to see that unibokk had a similar experience.