I was just browsing the web today and came across something interesting. I did a quick search here to see if anybody has talked about it before and didn’t find anything.
Has anyone seen either of these GUnis? They were both made by Keith Mackay. The second one, with the two exposed sprockets, is the latter of the two, and reportedly much smoother in operation. I think I figured out how the first one works, but I have no idea how the second one works, as I can’t see enough detail, and I’m not smart enough to figure it out.
So, does anyone know anything about these, or can figure out how they work?
it seems that the top gear is attached to a thing that turns the wheel. so the cranks are free spinning without the chain. and the gears work like a bike. sorry i cant put it into words well.
The second one looks very similar to Pete Perron’s Purple Phase design, with a jackshaft on the frame. One of the bottom sprockets is attached to the axle and the other to the hub (which is like a fixed-wheel bike hub). The pedals turn the axle in bearings in the frame like a normal unicycle axle, but the hub is free to rotate on the axle like a bike hub. How much it’s geared up (or down) depends on the sizes of the sprockets used.
The first one is just weird. Looks like it’s probably a similar sort of thing but with the jackshaft above the wheel and covered by a guard. Makes it look a bit of a mess. Those wheels are interestinn though… they sort of look like they have no normal rim - like a solid cart wheel with a bike tyre just slipped over it.
AscenXion enlightened us with:
> So, does anyone know anything about these, or can figure out how
> they work?
Seems like there are two chains. A light-coloured one from the peddles
to the top sprocket. From there, there’s a darker chain going down
again to the wheel. Both chains have different sprockets on both ends,
so both chains increase the rotational speed.
Sybren
The problem with the world is stupidity. Not saying there should be a
capital punishment for stupidity, but why don’t we just take the
safety labels off of everything and let the problem solve itself?
Frank Zappa
No, just some guy that began unicycling when he built the first uni pictured, and now he rides the second one every day around some soccer field in England.
I just didn’t look closely enough at that second picture. I now see that it’s the same thing, just on one side as opposed to both.
So, given that they are almost exactly the same concept, just that one is single-side driven, and the other in dual-sided, can anyone shed any light as to why the single-side drive would be smoother/better to ride than the other? Everything is in a fixed state, so is it just a frame flexing issue, or what?
Pedals and cranks turn a cog A that is free-spinning onthe hub.
Chaim from that cog runs up to a cog B above the wheel.
That cog B turns on a shaft, and there is another cog C on the same shaft.
A chain from cog C runs down to cog D that is attached to the wheel and turns it.
That’s my guess. It gives two opportunities to change the ratio: the chain between A and B, and the chain between C and D. Cogs B and C are on a common shaft and turn at the same speed.
It looks a bit Heath Robinson, and he would have got better results just shortening the cranks and learning to pedal faster.
