I don’t ride muni (yet). Until I read the comments that tholub and Eric_aus_Chemnitz wrote, I didn’t realize that the seatpost shock wouldn’t help with landing on your feet. The impact is transferred through the tires, to the rims, spokes, hub, crank, pedals … and then to your skeleton (ouch).
The springy seatpost would only serve to destabilize you at that point.
What about making a hub out of a tube, with flanges on either end with spoke holes on it, that has a tube of rubber inside as a shock medium, and inside of that has an axle with ISIS mounts on either side or something? That way the spokes have something to pull on, and the hub can bounce around in the rubber - but still be held in place by it? I’m not good with pictures … or words …
Suspension is not inherently bad on unicycles, but it’s quite difficult to design a system that would work for real MUni. You have to locate it in the wheel, cranks, or pedals, and there are no really great designs to emulate from the bike world, where suspension is in the fork and frame.
Best we’ve come up with so far is fat tires and wide rims.
Sure you can, and I have often wondered how that would feel. A suspended fork just like on a bike. This is essensially the same as suspending the seat post. Your body wouldn’t know the difference.
As pointed out in the thread you have your feet on the pedals, which would not be suspended by the frame.
So, just had a shower thought of how to achieve suspension on a Muni in a completely impractical manner. To suit the impracticality, i’ve sketched the idea in Powerpoint.
Essentially it uses a connector between the hub and stub axles to maintain chain tension while being able to rotate around the wheel. I didn’t say the idea was good.
A suspension geared offroad unicycle… A geared full-suspension muni? A full-sus off-road guni? A suspended guni-muni-uni that looks kinda like a Huni? A gumuhuni??
To put suspension on uni pedals, i think the only option would be a chain/belt drive system. Somehow this needs to move relative to the hub while still maintaining chain tension.
I can think of at least the following reasons it would be bad:
Backlash - a chain drive introduces backlash.
Width - it would be very wide.
Suspension driven acceleration/deceleration - when the suspension is compressed, it’s going to apply extra forward movement, reverse for extension. This might be less of a thing and/or quite useful sometimes.
Rideability - A Huni, giraffe or one of the Chain Drive 36ers is easy(ish) to ride because the cranks are still in line with the hub, it feels wierd but it works. Bringing the cranks forwards or back of the hub means you can never leave the saddle/bars or you are coming off…
I mean I kinda want to try that. Probably super weird to ride and a pain to set up the chains to not lose tension, but it could actually work once you get used to it.
Hold up I actually had an idea i called the turducken tire, ill post a picture later though you might be able to find it somewhere on here. It would be very hard to do but I think I can add my idea to yours to make something somewhat functional. let me go grab my weird bike items real quick.
im replying mostly to your last comment here> i am in the process of making a geared 32” via chaindrive, same as you mentioned. im sure youve seen a Vframe, the seat is tilted to allow it to ride properly, a similar thing could be done with the idea that davejh had but the seat placement and angle of the shocks and maybe a secondary tilt linkage on the seat could keep the wheel from kicking forward or backward
The up/down movement of the suspension will cause the crank axles to move back and forth relative to the seat (just because the geometry of the ‘frame’ is changing with the extension/compression of the suspension).
In addition, I think the up and down movement will also translate to rotation of the cranks (think of how the sprocket on the hub moves in relation to the centre of the crank axle when there is linear movement up and down on the suspension) – so the cranks are still tied to the up-down movement of the suspension and in essence it is not any different to if they were connected directly to the hub axle (which is the degenerate case of your geometry).
If you want something that would work to dissociate the cranks from the suspended hub axle, think of how you could efficiently make a vertical splined shaft drive with the splined prop-shaft moving parallel to the suspension movement (say with a ball spline). You’d have to efficiently have two right angle drives to change rotation to vertical and back, and do this on both sides, probably via a jack-start arrangement…..
This is a 13x5” lawnmower innertube, a 16” rim, and a chain guard for an exercise bike. If we make a hub with hooks for a tire and make studs in the top of the tire we can bolt it to the 16” rim, then we can drill holes in the side of the rim and use it as an intermediate hub to the size rim we want and still be able to fit a tire with a valve around the outside. The chain guard represents a precautionary guide mounted to the 16” rim to prevent the center tube from sliding out of place. Ideally the 16” rim should be a fat rim so the spokes have a decent angle and don’t potato chip.
Dang that’s a pretty nice idea. If the centre of the hub is also splined that would allow for removal of the wheel and no need for chains. Problem is going to be finding something strong enough to take abuse while not making the uni absurdly wide.
I’m not sure if a seat pivoting mechanism could really save the last idea, to fit a chain drive and have reasonable travel, the cranks would have to be well forward or back of the hub. While recumbent unicycles have been done before, i’m not sure i’d want to try muni with one!
Using an intermediate rim looks like a cool idea to allow for mid wheel based suspension for solid tyres or to add a bit more softness.
Yeah there’s a lot of trial and error necessary to make the seat pivot work but it might.
that splined shaft is a great idea, I don’t know if it could work but a normal bearing with the inner race removed should provide a linear no rotation slide.
The intermediate rim is from a dud named Marty who made a 49” ultimate wheel
@lobbybopster : sorry for the question that you may have answered in your project’s thread but how engaged of a muni ride does your design can sustain? And any weird side effect when the suspension compresses or returns? How do you set your saddle height for muni (similar to regular muni or maxed like for road riding) ?
I am not lobby booster but the pictures look like it’s got a linkage to a small seat tube, I don’t see any clamps so I assume he knew exactly how high he wanted it when he made it. I could be wrong though.
You are right that his creations are tailor-made. However, as some part of this thread is about the challenges of riding with a variable geometry uni (vs the benefits of having some form of shock absorption), I tried to tag him so he can share his experience and help the global analysis to move forward
I have not read through this entire thread so forgive me if I am being redundant. I remember a few years back of reading about and seeing a picture of a unicycle with a suspension frame that a forum member had in their collection. Can any one else recall that?
So was the muni at the top of this thread every built?
It looks quite cool, though I could imagine it will feel strange to ride like that, when the spokes are springy.
