Of course you are right Klaas, perhaps a trilogy!
I. Wheel Size - why so many.
II. Crank Length, it matters
III. Geared Hubs, Schlumpf’s revenge
Awesome idea. And then somehow weave the overarching concept of Total Gear Ratio in there, or maybe as part IV of a quadrology 
A thorough discussion of the overall ratio should consider the geometry of the rider’s legs. As part of the complete drive mechanisms we consider the main forces are applied in two different places and the articulations of the knee and ankle.
Most riders who have experienced a range of unis will know how much faster one can pedal by having the seat high enough to minimise the bend in the knees and strongly articulating the ankles on a uni with short cranks.
Despite the decreased leverage of the shorter cranks, hill climbing ability is not severely sacrificed because the efficiency of the transfer of the energy improves in the leg itself.
I’m actually working on a model that includes leg motion, ankling, seat height etc. But the Total Gear Ratio is aimed at being similar/comparable to the gear ratio of a bike. In other words: it is a property of the cycle, not the total drive mechanism. For that reason, leg geometry and motion are not included in TGR.
Yes I suppose the leg is more like the engine than the transmission.
I’m just trying to decide on cranks for my geared uni build and seeking advice.
Currently, I am really enjoying hill climbing with my KH36 with 110 cranks and on the way to work, I regularly climb one hill that is 10-13%. On the weekend at Berowra waters, a 4km climb 5-7% grade I enjoyed overtaking fancy bikes and staying ahead.
My thinking is that I want to get VCX 114mm cranks on the geared uni, so low gear riding and hill climbing feels same as KH36 and use high gear for the flats, which puts it in the “danger” zone on the speed chart… that kind of sounds quite appealing (knock on wood)
Currently, I’m not liking to max out on the cadence with the 110 cranks on the flats and would be happy to turn a big gear with the potential speed to be limited by my strength and not cadence.
Am I missing something here?
I’m thinking If I need longer cranks in the learning phase, maybe I could use my KH spirits 125-150s.
But I guess I do not want to be changing cranks too often with the Schumpf 2022, so may just install 114mm cranks and just get used to them.
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I’m not an advanced rider but these will in my view work and be on there for a very long time.
Personally I cannot picture riding a geared 36” unicycle with 114. And that’s not even if I were to get super proficient. I think the gearing kind of requires more torque arm to leverage and below 125 you’d just not have what is needed.
Sure there may be that one person who can do that. But the lowest I picture myself ever going would be 125. Perhaps a happy medium at 137. You’d get the 117 hole to see if that works for you but I personally suspect it would never be used in high gear.
I had to chime in solely as I’ve done a ton of thinking on this area, but naturally you’ll likely want to hear from those that ride G36ers a lot.
I do recall that most are on 150s/137s. You only need to check out the leader board off Unicon 20 for the race results to see what people ride to get an idea:
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It’s a simple, effective concept based on foot speed.
When it comes to comparing speed potential between 2 unicycles with the same TGR, the one with the biggest wheel will be the most efficient.
The choice of length cranks is not always related to performance.
When I ride my G36, it’s to ride fast on flat road (in high gear). I use the 1:1 speed to start or climb hills (but I don’t think it’s the ideal unicycle for climbing hills).
Some use short cranks on G36, feeling that the ride is smoother, and can hold high speeds on the flat or downhill without suffering.
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Thanks Felix,
Those race results really tell a story.
I do see a few g36 with 110s and 114s further down the ranks.
I’m not planning to win any races and have got to like 110s on the KH36 and am thinking the feeling will be similar on the G36 in low gear?
Effectively I am making a “alround g36”
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Thanks Simon,
Yes not ideal for hill climbing, but I like your comment about smoother and holding speed.
I plan on getting the Shimano grx secondary brake as well. One lever left side near, and one right side on aero bars. So if need be I can use both levers.
I am getting used to riding down hills 10% at speed now, riding the brakes… and I’m thinking I might need those skills with the g36.
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Good plan! I plan to do the same (well, one lever on the left aerobar and the second one on the right of the KH t-bar). I just have to take my uni to the LBS to put on the secondary brake lever… It’s just 18 months since I bought the secondary lever 
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That link doesn’t seem to work, I get error messages
Strange. It might be a cache issue.
https://www.unicon20.fr/competitions/results/
This is the main page then select 10k unlimited results.
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I have ridden a 36" with 110 cranks ungeared and currently use moments 125/150 on my G36. It strikes a good balance but you need a lot of strength to push high gear 125 fast on flats and it’s difficult on any incline not to mention head wind makes it near impossible. 125 however is a great length in low gear and when you have the right conditions 125 is very fast. I don’t think I could make use of 110 or lower in high gear would be great for low gear cruising.
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That link does work, thanks!
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What a beautiful page! Who is the person behind this perfect UI? If I ever meet them, I’d offer them a beer!
(Feel free to do the same if you ever encounter them 
)
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Someone called Max apparently. Know idea if he’s into unicycles or the like 
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Ok, I’m starting to understand.
So this concept of torque arm is a factor.
So it is worth getting a multi-hole crank.
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I think this is probably why geared wheels are referred to by some via their virtual sizing - as in a G36er is a 54” wheel in high gear. This helps to give some idea of how it might “feel” with short cranks I think.
I had my first proper taste of high gear - and it (for me) was a big challenge to control the speed and at the same time make the wheel go. The way I like to term it: the wheel feels very heavy initially in high. And the weight or virtual sizing all feel like they benefit from a longer crank. Especially for controlling the run away speed of the wheel once rolling. Yes you can use the brake, but the confidence you get from crank braking I feel is key to feeling “safe” on a schlumpf.
150 is great for my foot sizing too for the shifting buttons and I like the option of 125. These do in my view feel like the perfect learning crank set for a geared wheel. Sure it is a downgrade in terms of being able to spin your wheel nicely in 1:1 - but I feel the aim really will be to get riding to around 10mph and then shift, and once you’re up in high gear the annoyingly long length of 150 in 1:1 will rapidly be forgotten about - and you’ll be glad that you have it.
I sense you’ll be a much quicker study then I am with getting acclimatised to high gear on your G36er - so as soon as you do you can try the 125s and that may be the sweet spot 
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Thanks Unigan,
I feel we have similar paths of progression and am nearing a decision for Crank length for my G36.
Do you think I could have the strength required for regular use of 125mm in high gear, based on my preference for unicycle climbing with my KH36 ( see images of last Strava for my last 2 weekends) basically I enjoy Hill climbing the KH36 with 110mm cranks. 3-4km on ave grade 6-8%
See below sessions Hill climbing Galston Gorge and Berowra Waters.
With the intention of covering my intended usage envelope for the G36.
My choice is narrowed down to either:
-
100/125/150 VCX. 150mm learning/normal. Or possibly 125mm normal if I have potential to do so. (What do you think?)
Change pedals to 100 to use as a climbing unicycle in low gear only when I reach a specific hill for climbing.
It would be a bit harder than my current KH 36, which I will keep as my Hill Climbing Uni with 110mm cranks. -
138 single hole crank.
Maybe, with practice, it could be possible for me to Hill climb in high gear? Based on my current strength and potential? (see Strava screenshots)
I would keep my KH36 with 110mm cranks as my Hill Climbing uni.
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