Shorter cranks on a 36er

I learnt to ride my 36er a few years ago using 170 cranks then moved to 150s pretty quickly. After a while I tried 125s and felt unsafe (too fast and less control) so went to some 145s which is what I still use today. I’m considering trying 125s again, but am a bit wary since injuring my knees a few weeks ago.

So a question or two for the regular 36er riders here…

If you ride 10+ miles with 125 cranks or smaller what is your average speed and what is your top speed? (I know there will be variables in there)

Also, with cranks of 125 or less, do you truly feel in control and safe on the 36er?

Finally, any tips for an old scaredy cat who wants to go down to smaller cranks on his 36er? Or should I just stay at 145?

Thanks good 36er peeps!

I’ve been using 127mm cranks on my 36er for the last few years. I generally ride between 15-40 km on a mix of sealed and dirt roads, with moderate climbs. My average speed usually ranges from about 16-20 km/h.

My highest recorded speed is 27 km/h, but that’s not sustainable for me. 22 km/h is a fast cruise that I can maintain if the conditions are right.

I find them a good length for the sort of riding I do. Any shorter and I don’t feel confident on dirt or in traffic. Any longer and they’re a bit frustrating on smooth flat roads. I never really feel out of control except for offroad stuff, like MTB trails. But I generally chicken out of those on the 36er before I have a chance to lose control! I can’t do steep offroad climbs. Steepish climbs on sealed roads are possible with practice (it’s technique, not raw strength).

I think the biggest safety issue with going shorter is when you need to stop in a hurry and suddenly find yourself with less leverage than you’re used to. If you’ve mastered emergency braking with your brake then that concern is alleviated.

There’s no rule to say that shorter is better; it’s really just a matter of preference. If you are going to go shorter, just recognise that it’s going to take a while to acclimatise. Ride them gently for a few weeks before you decide whether you like them or not.

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Thanks @lightbulbjim, appreciate your thoughts.

This is a concern for me because I’m either riding on local roads, or on the beachfront promenade dodging pedestrians and street furniture.

I guess that’s unicycling in general, I’ll need to build up the courage and practice somewhere quiet.

To be clear, I think 125/127mm are fine in these scenarios. I have experimented with 117mm in the past and found them a bit wanting in those circumstances.

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I learned to ride a 36er with 125mm/127mm cranks and then after about a year switched to 109mm. I tried 150mm once and it felt awkward and slow. Most all my riding is on country roads with grades up to 12%. I find the 109mm about 10% faster then the 125mm with less leg movement and less change for saddle irritation. I have never had a UPD related to the shorter cranks.

My average cruising speed is about 12mph (19.3kph) with the 109mm and max 17.7mph (28.5 kph).

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I might be an oddity but I ride with the pedal in the 100 mm crank hole (150/125/100) most of the time. I can go up relatively steep hills and down without a brake and don’t have much difficulty. I have been using 125 recently so that I don’t get out of control speed, last I checked I was averaging 6miles an hour. I am trying to keep my speed in check and stay maneuverable around traffic. I was using the 100 mm hole on my Hatchet 26” but I just broke my handles when I was out riding.

I can say I started using the 26” before because I was going too fast but after a recent back surgery I have been using the 36” carefully since I broke my handles on the 26”.

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Before switching to a Schlumpf geared hub, I have used 100mm and 89mm cranks on my Oracle 36er. They felt really great even for steep and short climbs, for offroad riding or for traffic.
My cruising speed was about 25 km/h and my top speed around 40 km/h.

Regarding other replies and other threads, I’d say shortening crank length won’t make you go faster or feel safer without a serious training.

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On my first 36er I started on 150mm and quickly went to 125mm. No problem with riding with this crank length, you quickly get used to it, and spins well. Just makes sure you wear safety gear (kneepads, wrist guards, helmet all highly recommended).

Btw, my leg length (77cm/30") means I couldn’t ride a standard 36er with cranks longer than 150mm without compromising the seat or frame. I have the seat all the way down.
And I wouldn’t call myself proficient with mounting a 36er. That’s my frustration. I have progress but its a real skill to develop.

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I hear you there @Gockie, until recently I was almost always using a street sign or lamp post to assist my mounting but in the last couple of weeks I’ve put a lot of effort in to freemounting my 36er and I’m way better than before managing to mount and ride off on my first attempt about 90% of the time. I just took quite a lot of practice, which as ever is the key to this sport.

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Thanks for your replies, I appreciate all the advice.
I guess I’m just going to have to give 125s a go and practice with them for a bit and then give it some more thought. I’ll let you know how I get on once I’ve got the shorter cranks on.

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Two things (aside from skill and leg strength) that can change how short you might want to go with your cranks are:

  • how proficient you are with a brake
  • and how heavy your wheel is.

With short cranks a brake is pretty much essential if you want to stop quickly, and a good way to ensure you can still ride down hills.

On weight, I’d say that a shift from the regular Nightrider tyre to the Nightrider Lite can make up for 10mm or so in crank length. Going to a carbon rim probably has a similar effect.

I stopped riding my 32" once the 36" NR Lite arrived on the scene, as it made my 36er ride almost the same as the 32" wheel.

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Thanks @mowcius, useful advice as ever.

I’m OK with the brake, using it doesn’t bother me

My wheel is a Nimbus Stealth² rim with a Nimbus alloy hub and an original NR tire, so I’m guessing it’s not as light as more modern wheel setups.

I guess my main question then is: What are the real advantages of smaller cranks?
From some of the replies above it doesn’t look like top speeds or average speeds are significantly higher than mine with 145 cranks, this morning I did a leisurely 17.6ks with a top speed of 16.3kph and an average speed of 12.7kph. So what would I gain by going shorter?

I guess it comes down to training: if you don’t train to go faster, you probably won’t gain anything. However, if you train to push your speed up, you could gain some speed.

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Thanks @Maxence

In the last few weeks of Aug and the first week of Sep I was pushing my rides to go faster (both average & top speed) and hit 22.2kph on one of them. Most of my rides around that time were hitting around 19 or 20kph and my average speeds were up slightly too. But then I had a bad UPD and mashed my knees pretty badly. I’m now at the end of my first week back on my 36er since the crash, so confidence isn’t quite where it was. Having said that, I am keen to increase my average speed more consistently so I reckon I just need to bite the bullet, get the 125s on and start riding and see where I get to.

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In my experience, although I can go almost as fast on longer cranks, I can’t do so as smoothly, and it’s harder on my body over longer distances (if on mostly flat ground).

I think the bounciness and increased side to side wheel movement caused by longer cranks requires more correction from the rest of your body making it more effort once you’re up to speed.

The side to side movement is also more significant when your wheel is lighter which adds to the feeling of perhaps wanting shorter cranks.

I’ve been riding primarily 110s for pretty much all the time I’ve had a 36er though, with only relatively short stints riding 127s or longer, so some of my thoughts are more based on my experience of changing crank lengths on other unicycles than big wheels specifically.

My speeds are normally about 16-20kph average depending on how fit I’m feeling, topping out around 34kph.

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That’s quite all right to use a post to mount in the begining. The important thing is to get comfortable on the larger uni and get riding down pat. You don’t want to free mount and find yourself on your face because you can’t handle rolling the tire over.

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Thanks @mowcius, that’s helpful

Thanks again for all your comments.
So I swapped the QU-AX 145s on my 36er with the KH 150/125 Moments from my 29er and had a great 18k ride this morning.
Freemounting initially felt harder but soon I realised that all of my concerns about shorter cranks (going too fast, loss of control etc) were in my head and quite easily overcome, so I look forward to riding on them some more later this week.
One big thing I did notice straight away was just how much smoother the whole ride was. I wouldn’t have believed such a difference was possible but it really is! So I’ll stick at 125s for now and maybe in a few months I’ll give some shorter cranks a go.
:blush:

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Same for me.

I use 125s and average @ 10mph. I always wear wrist guards.