Has anyone made a modern version of this design, it looks as if it would be functional and relatively easy to construct?
I haven’t seen a thread about this in the past two years, sorry if it’s already been discussed.
Check out the purple phaze:
Ah, so that’s what the purple phaze is based on, I’ve never seen a photo of it.
In that case, this thread might as well be left to die, it looks like the idea has already been resurrected.
George Barnes made a similar design within the last few years. Peter’s is rather current. They differ from Pete Perron’s PurplePhaze and OutaPhaze projects in that they don’t employ a jackshaft through the hub. Dave Stockton sells the Perron designs I think.
If you look at Peter’s design and picture the elevated cranks on the frame being replaced by two chain cogs on only one side of the frame with an axle that runs through the hub you start to get the idea. The axle has a cog attached to it. The axle goes through bearings in the hub and the hub has a cog attached to it. Two short chains run, one from the jackshaft to the first frame cog and one from the second frame cog to the hub. It’s a sweet, strong, simple design.
George Barnes made a geared unicycle with that design. Thread about it is here: Another geared unicycle… Unfortunately, all the links in that thread are dead so I’ll attach one of the pictures here.
Jackshaft?
Can anyone explain the Jackshaft to me? It looks the same or at least similar to the other designs… but it sounds different from the disscussion about it…
are these possible to buy?
Yes, but currently development of them is on temporary hold. The price is unknown at this time.
Though the finished product should be cheaper than a Schlumpf, unless they are made in large numbers they probably won’t be much cheaper. The upside will be that they are mechanically simpler, so you won’t be dead in the water if something breaks inside your hub. But otherwise I’d go straight to the much more elegant, lighter and shiftable Schlumpf design.
The engineer in me cringes at the way you are throwing around these terms, John, with no substantiation or justification.
About the only thing I could agree with is that the Phaze approach is “mechanically simpler”. However, that does not guarantee not being “dead in the water” if a hub part breaks. Field (or non-factory) serviceability must be designed into any device to be effective.
The cost of an item of whatever complexity is not just a function of number of parts, but of demand, production line, material costs, and many other factors. It is often the case that a simpler thing costs more than a more complex thing. For an extreme example, a diamond is likely to cost more than a pencil, despite the pencil being more complex.
“Elegance” is a subjective term, but to an engineer, elegance is a combination of strength, simplicity, effectiveness, serviceability, ruggedness, weatherproofness, appearance, and other factors. Oftentimes, a customer only realizes an item’s elegance when he finds that servicing it is easy, or he finds that his product fails much less often than a competitor’s product.
Lighter - I haven’t seen any data or setup that allows the two designs to be compared weight-wise. Have you?
The Purple/Outta Phaze setup is shiftable, moreso than the Schumpf. Perhaps you meant shiftable-while-riding?
Thanks for listening to my comments.
For a large wheel, the assembly could possibly be inverted, meaning that the axis of the pedal/crank apparatus was lower than the axle/spindle of the wheel.
On the other hand, that would produce minimum inseam problems. Would be interesting, though - a low profile “dropped” Coker… 