Not another geared uni. New idea.

Everybody has heard about how incredinle it would be to have a geared uni and then uni.5 came out, but know what about this idea. Instead of using gears to change the ratio, change the crank length. If someone were to have really long cranks (stay with me this is just an idea that’s not very well thought out). You to the cranks and attach something to them that can hold pedals that will slide up and down and a super strong spring pushing the pedals to the end of the crank. now if they used a gear shifting mechanism to pull that would apply pressure to the pedal pulling it upwards or without a spring just having a strong cable that would hold the pedals up or down after you pull it into position. I know that’s a lot of confusing garbadge, but could somebody help me sort out these ideas. Plus I don’t have the skill to do thid unless it was reaaly easy so would somebody be willing to help with some prototypes. Thanks


Sorry about all the mistakes I why so excited.


I seem to remember something about adjustable crank arms… which would solve your problem…
but they were every expensive.
Or maybe it was my imagination.

Interesting. But wouldn’t it be hard to get something to hold the pedals in ploace strongly enough?


Andrew, that’s why I came to you all, for ideas to evolve my idea.
Samuel, if you remember anything about it or find it again please post. Thanks


Adjustable crank arm threads:

Adjustable cranks

Adjustable Cranks (2)

I’d recommend you look at these discussions, there are some interesting ideas in there.

Samuel, that’s not what i’m talking about. I want something that one can move up and down while riding to increse there speed.
Thanks anyways.


the problem I see with having shorter cranks rather than gearing up is that you still have to spin the at high rpm’s to get the speed up.

Adjustable crank arms would be useful. Making them adjustable ‘on the fly’ would be difficult, unreliable, and possibly dangerous. The simplest answer would be cranks with multiple drillings for the pedals. Otherwise, some telescopic arrangement with threaded ‘barrel’ adjusters might work.

BUT changing cranks length is not exactly the same as introducing gearing.

A change of crank length does change the ratio between the distance moved by the feet and the distance moved by the unicycle. It can make it easier to climb hills, or easier to proceed quickly on the flat. To this extent, it is a form of gearing.

However, gears in the more common sense, as used on cars, motorbikes, bicycles and the Uni.5 do more than that. They allow the power source (engine or legs) to operate in its efficient/comfortable zone, whilst changing the ratio at which this power source is connected to the final drive.

So, on a bicycle, it is generally agreed that the most efficient way of putting out power (for a normal non-competitive rider) is to pedal with cranks of approx. 170mm, at a cadence of about 80 rpm or so, applying only a small amount of torque. So the bicycle is set up for the rider to pedal at his/her preferred cadence, whiclst changing the gearing to the back wheel to adjust for terrain and wind resistance etc.

On a unicycle, the shorter cranks change the ratio between foot movement and unicycle movement, but the ergonomics are changed. Pedalling with very short cranks feels very different from pedalling with very long cranks. Take this to logical extremes to consider:

A 24 with 6 inch cranks has cranks as long as 1/2 the wheel radius.

A 20 with 5 inch cranks also has cranks as long as 1/2 the wheel radius.

Assuming constant foot speed, the two unicycles will travel at the same speed. This seems ‘not unreasonable’ at first glance, and my experience suggests it’s about right.

Now get a Coker (36 inch) with 9 inch cranks. That’s 1/2 the wheel radius. Will it go at the same speed? Do you want your feet travelling in an 18 inch diameter circle?

Now get a 4 inch wheel with 1 inch cranks. That’s the same ratio. Will you keep up with the 24 and the 20? Er… probably not. :astonished:

So, I agree that adjustable cranks would be a good idea. They would help you to adjust for speed or hill climbing, but NOT in the same way as gears. And as for adjusting them on the move… nice idea, but too much to go wrong. Good try though. :slight_smile: