long cranks and knees

I was wondering what the consensus is on knee damage and crank length; i remember from past threads that some thought the torque of short cranks were hard on knees, while others thought the large turning circle of 175’s was a problem.

Just done a search and found: -


So i was wondering if Erin did o.k. with the 150’s, and also if people like Mike Fule had any new insights on this isssue.

(also, what’s the best way to refer to past threads, I just copied and pasted from the browser bar)

Hi Dave,
yes, well I have had lots of time to experiment with various cranks since that post…

I now have 127’s on my trials and also on my 29’er, 140’s on the 24 inch Sem XL freestyle and 158 Monty’s on the MUni. I am happy to report that none of these various cranks have caused my orginal biking knee injury to be aggravated.

I guess the only thing I have noticed is that if I ride hard for 7 to 10 days in a row there is a bit of a ‘tightness’ (like an elastic band ‘pulling’ ) over the top of my right knee - the one that does most of the work correcting . But this goes away quickly if I give the uni’ing a rest for a day or two.

All in all, I feel lucky that uni’ing is not irratating any old knee injuries and not causing any new problems, that is no new problems if I remember to keep my obsessive riding in check. :smiley:


It all depends on what kind of knee injury you’re trying to prevent. Some kinds of knee injury are aggravated by longer cranks and lower seat height.

I had a brief bout with Iliotibial Band Syndrome (ITBS) in my knee. It’s a type of knee injury that is aggravated by longer cranks. The combination of long cranks and low seat height cause the knee to move through a range of motion that allows the iliotibial band to rub and once the iliotibial band gets irritated it starts to hurt (and boy does it hurt). ITBS is also known as runners knee or cyclists knee. A Google search on the term will find you a lot more info. <http://www.itbs.info/> also is a good starting point for more info. A forum search will also find info that I’ve posted in past threads about it. Proper stretching is the best way to prevent getting ITBS. And <http://www.itbs.info/> has some info on they types of stretching that are helpful.

But not all knee injuries are caused by the same factors. So the general answer about long cranks causing knee problems is it depends.

Hey, thanks a lot for that link! 3 weeks ago I started to feel exactly this kind of knee pain as I rode for 5km on a sloped road; it can really hurt a lot. I rode 5km from my car and felt nothing, but on the way back with the slope the other way it hurt in the right knee. Oh well, Murphy… .


I’ve had knee problems in the past but it wasn’t to do with crank length (150 on 24X3 & 127 on 20”). I have strange knees anyway as they bend backwards (the look on my physio’s face when I showed her :astonished: ) and my knee problems were resolved by stretching and supplementary exercises not changing crank length. I would like to try 170’s on my Muni but I don’t won’t to bye some just for the experiment (got any loaners lying around Mike :wink: by any chance).

Cheers, Gary

Thanks for the tips and links.

I don’t think it’s ITBS cos’ that sounds like it involves lots of pain.

My situation is that when I ride for several hours a day, the next day I feel my knees are ‘unstable’, it’s not a pain, they just feel fragile. I’m aware that knee joints are not the sturdiest of things and as I’m 36 I feel the need to not agravate them.

On a slightly different tack, last summer I spent so much time unicycling that at one point I walked to the shops and it felt really strange to be on foot, as if there was something missing.

Years of study of human nature suggest to me that anyone who rides enough to do real damage to their knees will ride enough to damage their knees, whatever advice they’re given!

I think knee problems would arise from overly long cranks, especially coupled with a low seat.

Pinned pedals can be a problem in that they can hold your foot at exactly the same angle for too long. I make a point of wiggling my feet about from time to time.

On very long rides, I might also move my seat up or down 10mm or so just to vary the pedalling action a bit.

The other thing is, build up to a level of fitness. How many people don’t get out on the uni for a week or two (or only tootle round the back yard or the local parking lot) and then get a free Saturday and spend all day riding hard? Is it then a surprise if the day’s hard riding surprises the old muscles and joints a bit?

I once did just over 50 miles on the Coker/125. A lot of that was on a noticeable slope. That hurt my muscles above the knee.

A week ago I did an hour’s ‘time trial’ and the next day, my legs hurt. This week I did just as hard a ride, and they didn’t.

I dance every week, and since I’ve been unicycling as a serious sport, my knees and feet are stronger and I get fewer problems.

Gary: sorry, I gave away the 170s, but I can lend you some 89s. :0)

I was having problems with my left knee after starting to learn. This knee has had a rough life, and at 15 spent 3 months in a full length cast. I to this day can go about 2 inches past the locking point of my other knee. I haven’t kept myself from doing any activity as a result of the injury. On occasion though I will aggrevate the old injury by over extending or pivoting my body while the foot is fixed.

I was starting to get some debilitating pains on the outside of the knee, and franticly searched this forum as well as the internet looking for the cause as well as the cure. I was making progress on the Uni and really didn’t wan’t to give up. I started doing excercises to increase the strenght in my quads and hamstrings. In addition I started stretching everyday.

Since I started this routine I haven’t had my knee bother me in the slightest. If you have knee problems that only bother you while Uniing, my bet is you can correct it w/ excercise and stretching. Of course “but what do I know?”

Knee Damage

I find that Unicycling is comparatively very low impact. The stress on your knees is nothing like running or tramping. I guess that short cranks are less stressful on joints due to less movement in the arc but the forces involved might be more stressful when accellerating or stopping in a hurry. After walking around (and up) Mount Taranaki I have never found unicycling to be too tiring. The worst knee damage I have ever experienced, was when I practised one footed riding on a giraffe. I could go with my foot sticking out the front without a problem. Then I tried pulling my foot up behind me. I lost balance, and with my right foot on the pedal the giraffe catapulted me forwards. By the time I swung my left leg forwards I had no time left to prepare both feet for an even landing, and all the forwards momentum of the giraffe impacted sideways into my knee. I walked with a limp for ages after that. It was a lesson for me in gravity and knee vulnerability.