"moving to shorter cranks" question

Have a Nimbus 24 with the stock cranks…I think they’re 150s. Thinking of moving to shorter cranks.

How would I find the difference? What would it feel like compared to the longer cranks? For example, what is more difficult? What is easier? Any suggestions on size?

Thanks for any input…

Talking generally and stripping personal preference out of it (As much as I can…), short cranks will essentially up your gear very slightly. You’ll move your feet in smaller circles, and so things that require force on the pedals (hillclimbing is the common one) will be harder. You might find, though, that pedalling up at speed will be a lot smoother, you’ll do less mashing your pedals from top to bottom of the stroke, and more spinning in a circle.

With shorter cranks you’ll be able to spin the wheel a little faster because your legs don’t have quite as far to swing up and down. Shorter cranks will require more leg strength to control the thing. You may not be able to tackle hills quite as steep.

I have a 24" with 150mm cranks that I’ve ridden for 30 years. I used to be able to ride farther than I can these days. Last summer I got a set of 127mm cranks and tried them. I live in flat lands. There aren’t any hills around here to speak of. It took me a couple rides to get used to them, but overall I like them. However, I found out that my current leg strength and endurance levels are calling for the 150mm cranks for a while yet as I attempt to get myself back in a little better shape. I’d like to move back to the 127mm cranks after a time.

If it it your first crank length change I would suggest going with 125mm (or 127mm whatever is available)

You will definitely notice a difference between the two sizes. Mounting the unicycle and slow maneuvers will take a bit of practice but you will find it is easier to keep momentum with the shorter cranks and you will become a smoother rider. Climbing won’t necessarily be harder as you will be able to keep a more consistent spin staying out of the “pedal mashing phase” a bit longer but once you slow down to that point you might miss the leverage of the longer cranks.

Trying shorter cranks will make you a better rider even if you switch back to the long cranks. Your body will remember the smoother riding and you will find the 150s very easy to use but a little bit slow.

Anything that’s been written above is true. But on a 24", the strength required by shorter cranks is not hugely different and it doesn’t take too long to get used to it. My 24" has 137mm for muni and 110" for xc riding, and it’s pretty fun. I had 125 on it for a while. I find 150mm overkill for such a small wheel.

Funny you say that. I tried putting long cranks back on my uni and it felt exhausting! My legs had to travel much more, making for a twitchy uncomfortable ride.

I would suggest buying a set covering the entire range. I ended up paying for postage at least three times and still want to try more.

The 150’s on a 24 inch give a very large amount of torque but require a lot of leg movement. so i went to 125 then to 110 and am now on 100 and 89. I do use them on my old qu-ax thq-33 with a 24 inch wheel which needs square crank holes and not the isis interface so these are very cheap but still. On short cranks i can achieve a high speed for a 24 inch and have a fair range. Also check the range of the seat post because the short cranks require a higher seat post position.

I own pairs of 114, 127, 138, 150 and 165 ISIS cranks. The three unicycles I ride (trials/street, mUni, road) are all ISIS compatible. Changing crank length has helped me progress in my riding. My most recent experiments with crank length are on my 29" road unicycle. I’ve ridden it with 150, 138 and 125 cranks. As it was previously mentioned, I could speed up hills better on the shorter cranks, and the feeling of spinning the pedals, rather than pushing them down, was definitely better with the shorter cranks. However, I felt my legs were burning more after climbing a hill with the shorter cranks. There are some pretty steep hills in my neighborhood, and, using shorter cranks, I either keep momentum, or get off and walk. Another scary thing: If I’m using short cranks and feeling weak, I may lack the strength to pedal faster and thus avoid a UPD. Riding in traffic is fairly new to me. I would rather, for the time being, ride more slowly but with more control.

After riding a few times with shorter cranks, then returning to the 150s, I felt more comfortable mounting, idling, riding backwards, stand-stills and general goofing-off…on the 29". Conversely, using shorter cranks felt better while riding forward, but was scarier and inhibited me from wanting to try other techniques on the 29".

Relative beginners have to be careful, I think, about emulating the setup of more experienced riders whom are more efficient, more experienced, and whom can handle shorter cranks. There is a natural progression toward shortening cranks, but I don’t think it should be forced. A lot of the conversation about shorter cranks involves riding greater distances and riding faster. There is more to learning unicycling than distance and speed, and for all the other stuff, longer cranks have been, in my experience, a better learning tool.

Yes, that’s just how sadly out of shape I am. I like the feel of the shorter cranks and I want to get back to them. But for me right now, they require so much more leg strength that they wipe me out in no time flat. After several years of hardly touching the thing, I started trying to ride more last summer but didn’t get to as much as I wanted. I want to make more effort this summer and get myself in a little better condition. I did also get myself a set of 137mm cranks for the thing. With a step halfway in between, maybe I can ease myself back into the 125s a little more easily.

Remember that if you shorten your cranks, you need to raise the seat an equivalent distance. If your seat is too low it will be pretty tiring.

To get accustomed to the shorter cranks, go out on a ride and just concentrate on riding smoothly (not necessarily quickly).

It happened that I also got a new seat at the same time as the new shorter cranks, and it required a different seat post. I didn’t measure and compare seat heights. I set it at whatever felt comfortable. If anything, my tendency has been to set seats too high, whether on unicycles or bikes.


Thanks to all for the great suggestions, anecdotes, and basic advice. I guess I’m off to buy some new cranks. :slight_smile: