Physically, I don’t think there’s a significant difference between how bikes and unicycles use gearing. With bike-length cranks, we should be able to push the same kinds of gears that fixie riders do. There’s no particular reason why you shouldn’t be able to run a 80"-90" gear in a flat time trial, for example. Similarly, you should be able to gear down a significant amount. We can ride a 12" unicycle, why couldn’t we ride a 12" gear?
The thing that’s different is that it’s scary to go that fast on a unicycle, and our geared unicycles have slop and sketchy shifting systems.
High gears on unicycles become increasingly hard to control, so it’s not quite the same as on a bike where you’re just providing power to drive the thing along. But probably with practice a good rider could make use of a pretty high gear. Personally I find it very hard to ride a Schlumpf 29er on 150s, which is only about half of a bike on a 90" gear even allowing for the shorter cranks. But people who ride gunis regularly are happy with Schlumpf 36ers on 125s, so perhaps it’s not such a problem with practice.
What’s the highest gear anybody’s been known to ride on a unicycle I wonder? That thing Jogi built with external epicyclic gearing (steampunk work of art!) was about 2.5:1 on a 28/29" wheel wasn’t it? So something like 72" - and somebody raced that at Unicon XIV so it was certainly doable.
Also because of the wheels’ inertia, stability increases on a b*ke, but for us instability increases at high speeds do to the slop in the hub and the wobbling from the cranks.
Eventually I bet all the slop will be taken out of the hub, so that wouldn’t be contributing to instability, but I can’t see how one would counteract the wobbling from the cranks/pedals aside from holding onto something like the handle or bars.
Low gears would work great (to a point of ridiculousness, I think). High gears would be much more limited. Everyone remember their first few times riding a geared unicycle? A geared 36" in high gear? Hard to handle, and hard to master. Raise the ratio and it gets progressively harder to master, to the point where it might be no fun at all.
I once rode a short giraffe with a 3:1 ratio, on what I think was a 20" wheel. I could ride it, but the idea of using it to go real fast just seemed stupid at the time. Especially as it was a giraffe, with a small wheel below the crank axle. On a heavy 36" wheel it would be more stable, and probably easier, but I’m having a hard time trying to picture 3:1 on a 36", knowing what 1.55:1 feels like. I think it would reach a point where the stress level on the rider, both physically and mentally, would really suck. But we have yet to find out how high that would be…
Yes, it is a lever. But you don’t notice when riding. And it’s nothing that affects the stability of the frame. In early days of geared unicycles there was much discussion about that torque effect. People suspecting it would bend the frame, or make the unicycle unridable as the frame would be forced forth or back resulting in immediate dismounts. But nothing of that happened.
You feel the additional weight, especially when riding uphill or downhill.
Then there is some axle tolerance. That is something you notice, but it does not interfere with riding. It kind of feels like a loose crank. But you get used to it quite soon. The only thing you need to be careful about is when the crank actually comes loose. That is harder to notice compared to a non-geared hub.
A Schlumpf in 1:1 gear is more or less like a normal unicycle; somewhat heavier and with a bit of slop, but not anything you’d have a problem with.
A Schlumpf in high gear is significantly different than a normal unicycle. A 24" Schlumpf is much harder to ride than a 36" ungeared Coker, despite the gear ratio being similar. That’s partly because when you’re in high gear, the frame is constantly pushed forward by the lever action of the hub; learning to counteract that action is a skill that takes many hours of riding to perfect, and for me it still causes difficulty in situations like riding down steep hills under braking.
Live Wire Unicycles one made a unicycle witha 4:1 ratio! It was raced on a track.
I think that learning to master higher gear ratios is easier that learning how to ride.
The first time I tried a KH with a Shlump gear it only took me about 7 tries to actually start riding it some distance. Within ten minutes I was riding it cross country. The higher gears are different but once you get used to them they become second nature.
Because a uni does not have the stability of a bike (two wheels, bars), controlling the additional “torque” that is required to push the pedals in high gear on a uni leads to descreased stability. That instability is amplified by having a smaller wheel. The only way to increase stability in high gear is to spin faster, which reduces torque. This reminds me of a HP vs Torque, discussion in automobiles, each use having an advantage/disadvantage for different applications.
For muni, since we are often riding slow, climbing, and working over obstacles, the application and control of torque is going to be a key issue, whereas on a road/touring uni, HP is more applicable, at least on the flats.
Shifting a Schlumpf is not hard, but it is akward, and if you miss your shift it can be a pita. If we had multiple gears, more than three, I’d think that this would necessitate a remote shifter.
Someone, I can’t remember who, asked me a very important question when I was considering a Schlumpf:
“Do you really want to go faster on the trails you ride?”
My answer then was “yes”.
Now that I own a guni, My answer now is “no”.
I can go plenty fast on trails with a 29er
Do you know of some mechanical reference other than the frame with which to do this? I’m not trying to argue with you, I’m just not seeing another way to do it. If there is a way then the geared ultimate wheel would be realizable.