Problems with 165mm cranks on a 24 muni?

Hi world!

I am relatively new to unicycling. My friends and I began unicycling 3 months ago, and I am the first among them to purchase a higher-end muni – a Nimbus 24” x 3.0” with 165mm cranks, to be precise.

I absolutely love it. But I have questions about my choice in crank size.

When I climb uphill over any relatively sizable inclines, I seem to “stall out” fairly quickly when the pedals align vertically.

Also, when riding at full speed down the street, I find that my body bounces up and down as I pedal. Although the speed I am attaining is MUCH better than my original 20” unicycle, I never have had this “bobbing” effect before.

Are the problems that I’m describing typical for cranks that are too large? I’m beginning to think I should have gone with the 150mm.

I’m just wondering if this is a problem more likely caused by my cranks, or if it’s merely my inexperience.

–Jim Hettler

Hi Jim

Welcome to the world of muni, and the world forums!

Larger cranks have a bigger ‘dead spot’ that shorter cranks. A dead spot is an area of movement with the cranks that is more difficult than the rest of the circle. Shorter cranks (150’s) are a good length, and will have less of a dead spot and better for speed- but as a downside have less leverage.

Personaly I started off with 150’s on my first muni (and found them fine)without brakes. Longer cranks (eg 165’s, 170’s) on a 24 used to be the popular size for muni because of the great leverage, but these days 150’s seem to be a more popular length for offroading on a 24’’. Stick with these cranks for a while- it may just be that you need more time to get used to your very different setup :slight_smile: But long cranks do have a larger dead spot.

As for the bobbing effect long cranks are less smooth for speed and some people do find they ‘bob’ around with longer cranks- longer cranks have a tendency to be more prone to bobbing about.

I think you should spend more time on your setup before going to shorter cranks, as these problems may lessen with more experience. Everyone has different prefferences for cranks so at the end of the day you can only find out what cranks work best for you by trying out the different lengths.

The problems are proberly a combination of inexperience and the long cranks.

Hope this helps! :slight_smile:

I have tried more crank lengths than most - my garage is full of old cranks from 80mm to 170mm with all sizes in between.

My KH24 came with 165s. I found it great for rough ground but incredibly slow on the flat sections between, and tiring to ride. I eventually started to dislike riding it.

I then put 150s on and it was like a new machine: faster, smoother, and with no detectable loss of torque or control on the rough stuff.

I tried 170s on my 26" Muni and I had similar problems.

I now find that all my unis have either 150s (if they are ridden on steep hills and uneven ground) or 125s (for generally smooth and fast) - with one exception which has 114s.

I would recommend 150s. You will be losing 30mm from the diameter of your pedalling circle. It’s a big difference and makes it far friendlier to ride.

I started with 165mm cranks on my 24" muni and recently switched to 150mm.

I’m finding that I like 150mm better overall, but I’m not climbing trails quite as well.

I occasionally had problems with pedal strike with 165’s, but I can’t really imagine riding < 150’s yet (I’ve only been riding about 1 year.)

For comparison, on my 29" (mostly road, a little muni), I rode 150mm for maybe 9 months and was amazed at how much faster 125mm was. I recently picked up 110/127 cranks for the 29" to try 110mm. 110mm is slightly faster than 125mm, but hills are much harder. I didn’t notice a big difference b/w 150mm and 125mm on the 29" when climbing roads.

The bottom line - if money isn’t a problem - then I’d try 150mm. It won’t feel as smooth as something shorter, but for muni I’d wait until I was more comfortable with 150mm before trying anything shorter.

As a long time 24" MUni rider I too have gravitated from using large cranks (165mm) to getting more comfortable with shorter ones. I think a lot of it (for me) came along with increased confidence and skill. At first it seems like you need the large cranks in order to be able to have the power to ride over everything. Over time, as your proficiency increases, you realize that you’d like to be able to go faster on the flatter, easier stuff so you naturally think to try using shorter cranks. Now I’m using 137mm on my 24" and like them a whole lot. They’re a pretty good comprise with enough length for steep hill climbing while not being overly slow on the flats. But that’s just me other’s experience may vary. I’m about to transition to a 26" and will probably start out with 150mm cranks but may too drift towards the 137mm again over time.

I don’t think you will ever find a crank length that works on a flat street and a steep off-road climb. I’d say 165 is a bit long but if you are starting out it might help you ride a few things that you wouldn’t be able to with a shorter crank. As MuniSano says, as you get better you can ride more stuff with shorter cranks.

I’ve ridden mine with 125s which fly along on swoopy singletrack but I struggle when it gets technical. I now ride 150s and keep the 24x3 MUni for shorter technical rides. I have a 29er for longer, less tech rides.

140 is my length of choice on my 24 muni … but when I bought a (big) 26 this length proved inadequate and I am now accustomed to use 160 … but for sure my climbing abilities declined … will I switch to 150? I don’t know.

Thank you all for the informative replies! This gives me the feedback I really need.

I guess the 150mm will prove to be much more beneficial in time, but for now since I’m still a noob, I will continue practicing with the longer.