MUni cranks and knee pain?

I am thinking of getting 150 cranks on my upcoming MUni …ok, ok it is still a fantasy at this point but I would like to get my first MUni some day soon.

Right now I have 127 cranks on both my 24 inch and 20 inch uni’s. I am happy as can be because though I ride like a madwoman pretty well every day of the week I don’t have any knee pain which had been a problem in the past. (Patello Femoral Syndrone from too much b*king.)

Anyways, I just have my fingers crossed that longer cranks won’t have any bearing on that old injury. The reason I wonder is because the PFS was especially a problem when I was pushing big gears and/or going up hills on the b*ke.

Anyone have any experience, good or bad, with knee pain and longer cranks?


…oops, that should read 150 mm cranks … and 127 mm cranks.

… it would be pretty tough to a hundred and fifty cranks onto any uni!!! LOL



I recently reinjured my knees from an overuse injury that I had over 20 years ago. I don’t know what the knee injury is called, so I don’t know how relevant it would be for your situation.

But anyway, I was riding 170mm cranks on my MUni with a 24 x 3.0 gazz. The length of those cranks bent my knee too much at the top of the pedal rotation, so I put on some MOnty 158mm cranks. This lessoned the angle of the knee at the top of the rotation and allowed me to raise the seat. All of which reduced that angle.

With 150’s, they are still pretty short, so I don’t think the range of motion at the top of the pedal rotation will be an issue for you as long as your seat is high enough.

However, you will run into a bit of a conundrum if you start riding steeper hills. The 150’s will be too short for adequate torque, which then puts more stress on the knee. If you get longer cranks, you can have the problem of the knee bending too much at the top of the rotation. damned if you do damned if you don’t.

My advice would be to go with the 150’s, make sure you’re seat height is correct and maybe go a little higher. Ride around on gradual hills for a while and then see how it goes. Then gradually go to steeper stuff. Take it slow and do it over a period of time, so you can tell when to keep going or pull back.

150mm cranks are pretty cheap. I had the Bicycle Euro 150’s on my Sem XLW for a while and they held up well. They run @25 bucks. So you won’t loose out financially on experimenting with them.

Hope that helps.

I used to do lots of bicycling (regular 80 - 100 mile days) and I think the effect on your knees will be different.

Most bicycles have 170 or 175 mm cranks (or did in my day!) but you are typically pushing a gear equivalent to anything from about a 65 inch to an 80 inch directly driven wheel, and can gear up to 100 - 120 inches, even on a standard bicycle. The lowest gear on my tourer was about 36 inches and my tandem went down to about 24 inches.

Compare that to your unicycle which will have a standard gear of say 24 inches. (i.e. whatever wheel size you choose.)

So, on the flat, there is virtually no resistance to pedal against on a uni. You just ‘twiddle’ along. On a bicycle, you’d feel silly pedalling a 24 inch gear on the flat.

This means that a unicyclist will pedal fairly fast but at low levels of torque. A bicyclist will tend to pedal at a lower cadence but higher levels of torque.

There are other factors too: you will tend to ride less distance on the uni, and will be less inclined to load up with luggage, or do 25 mile time trials… (unibiker may ignore this last point;) )

So don’t worry too much about the knees. :slight_smile:

150 mm cranks are comfortable. 170s feel a bit long and do work the knee joint a bit more. 110s or 102s do require a bit more torque. I’m sure you can’t go wrong with 150s as long as you know to stop if you feel pain on a long ascent or descent.

On a good smooth surface, a 24 with 150s will go up or down most hills you will meet. There is no shame in walking now and again.

I have 170mm cranks on my muni, and i uni a lot, not as often off road, but a lot in general. I dont experience any knee pain, but then again im im “young and restless” (14) so maybe im not the one you need to talk to.

Erin, how long are your legs? Gyppo wrote me a long note about crank length and trick-biking; the gyst of which was that long leggers like long crankers and short leggers like short crankers. Don’t like 'em, switch 'em. carjug

Well Carjug, its been a while since anyone asked me how long my legs were! They seem in proportion to my body as far as I can tell :wink:

I am 5’4" and my legs, well I wear 30 inch inseam jeans, I would say they are average length… so I guess I need average length cranks!

Anyways, thanks for everyone’s input here; as with most posters on this forum, you are all extremely kind and helpful.


Photos, please.

oooooh Greg Harpers got a crush!:stuck_out_tongue:



You bust me up! :smiley: Great timing.