(Roger, I invite you to contribute to this thread or correspond direct… £££)
What can people tell me about eccentric wheeled unicycles? I do a certain amount of performing, and an EWU might be a useful addition to my kit.
To clarify, by ‘eccentric wheel’ I mean that the rim is circular, and on a flat plane, but the hub is not central. The effect is that at one point in the revolution, the hub is higher off the ground, and at the opposite point, it is nearer to the ground. The unicycle proceeds with an up down, faintly nauseating motion.
My guess is that a hub which is about 1 inch off centre might work. That would make the rider’s up and down motion equal 2 inches. It would mean that there would be no huge disparity in the length of the spokes.
My guess is that the wheel would need to be built so that the cranks could be fitted in such a way that one was pointing directly towards the nearest part of the rim, so that that uni would naturally idle in one position. It would be essential to performing that the rider could be sure of stopping and idling confidently.
My guess is that the price would be more or less the same as a standard wheel, but perhaps an extra few quid because it would take longer to build.
My guess is that a 1 inch eccentricity would be more noticeable in a 20 inch wheel than a 24.
I’ve seen bicycles with eccentric wheels, but never a unicycle. Can anyone add to my meagre collection of theories/knowledge?
I think you will want the hub to as off-center as you can handle for the proper effect.
I’ll take a look at it tonight but I have a club uni in my garage that is like you describe. It is easy to ride but the up and down effect is not very noticable to the casual observer.
One of our kids had one built that is very off-center, more difficult to ride, but gives the appearance of a bucking bronco. In fact, when he performs he has a cowboy hat and waves it around like a rodeo rider. Quite amusing.
Could you build an EWU with a shorter crank to one side (so that the pedals were in the same place they’d be on a normal wheel)?
That way when the ride was sitting he’d bob up and down but if he stood up on the pedals all would be as before. Also there wouldn’t be any issue with pedal clearance.
Tom Miller has made wheels with off-center hubs, and has also made hubs with off-center axles. The off-center hub is nice because it can be put into any standard wheel, without having to customize all the spokes to various lengths. I have an old picture of one. I’ll add it to the list of stuff I should scan and post to my web site…
For shows, you probably want more than 1" of offset. This may not be as visible as you want. But you don’t want too much either, as this will make the thing a pain to ride. The examples on my Garage Page combine kangaroo cranks with a large offset, to keep the cycle relatively rideable. That much offset with regular cranks would be a lot of work to ride: http://www.unicycling.com/garage/ecentric.htm
A popular design for eccentric wheels is to put a horse saddle on. This is a plastic horse, such as from a small child’s hobby horse. Make sure the audience sees it before you ride it, because it will be hard to recognize with your body in the way. So they get one laugh at the look of the thing, and then a second laugh when you ride it and it goes up and down.
Plus a third laugh, at whatever you figure out to do while riding it.
This one is a one inch offset and is quite easy to ride. Most of us could ride it on the first or second try. The effect with the two inch rise & fall of the hub & seat is not very dramatic.
Norman couldn’t make it so I still need to find out what the offset is on his. I tried to ride it once last summer and found it very challenging.
I don’t know if it is standard but both Norman’s and the club’s were laced up on an existing 24" frame using a 20" wheel and are radially spoked.
Cool vid. But if I didn’t know the wheel was an eccentric, I wouldn’t have noticed it in the video. Are there any vids of someone riding the Eccentric Kangaroo?
I have only ever seen eccentric kangaroos, I have not see them used as
normal unicycles and when they are used like that the cranks point towards
the biggest part of the wheel and are long.
>
> (Roger, I invite you to contribute to this thread or correspond
> direct… £££)
>
> What can people tell me about eccentric wheeled unicycles? I do a
> certain amount of performing, and an EWU might be a useful addition to
> my kit.
>
> To clarify, by ‘eccentric wheel’ I mean that the rim is circular, and on
> a flat plane, but the hub is not central. The effect is that at one
> point in the revolution, the hub is higher off the ground, and at the
> opposite point, it is nearer to the ground. The unicycle proceeds with
> an up down, faintly nauseating motion.
>
> My guess is that a hub which is about 1 inch off centre might work.
> That would make the rider’s up and down motion equal 2 inches. It would
> mean that there would be no huge disparity in the length of the
> spokes.
>
> My guess is that the wheel would need to be built so that the cranks
> could be fitted in such a way that one was pointing directly towards the
> nearest part of the rim, so that that uni would naturally idle in one
> position. It would be essential to performing that the rider could be
> sure of stopping and idling confidently.
>
> My guess is that the price would be more or less the same as a standard
> wheel, but perhaps an extra few quid because it would take longer to
> build.
>
> My guess is that a 1 inch eccentricity would be more noticeable in a 20
> inch wheel than a 24.
>
> I’ve seen bicycles with eccentric wheels, but never a unicycle. Can
> anyone add to my meagre collection of theories/knowledge?
>
>
> –
> Mikefule - Roland Hope School of Unicycling
>
> It certainly wears this one…
> ------------------------------------------------------------------------
> Mikefule’s Profile: http://www.unicyclist.com/profile/879
> View this thread: http://www.unicyclist.com/thread/22949
>
>
I can see why the cranks would point to the high spot on a kangaroo. Looks like on a normal crank arrangement, I was right and one points towards the low spot (and one towards the high spot).
That leaves the question of how much offset. The feeling of the group seems to be 1 inch isn’t enough. Would 2 inches be enough? Would 3 inches be rideable? (Oooer, Matron, etc.) The principle I understamd, it’s the degree that worries me.
Roger. That’s 30 quid to BUILD the wheel, right? So given that it’d only need basic quality components because it wouldn’t be for regular or hard use, how much for so a 20 inch wheel with a basic rim, hub and bearings, tube and smoothish tyre? (It will not surprise you to know I have spare cranks aplenty:) )
All would only ‘be as it was before’ when the cranks were up and down (if aligned to the wheel), yes? At all other points the relative foot position wouldn’t be symetrical; would be interesting, though: an Avalanch of Eccentricity.
I spoke with Norman and his dad. He used a 20" wheel in a 24" frame with the maximum offset so that the tire barely clears the frame. That would probably be a 2" offset and a 4" rise and fall of the seat.
Norman said it took him several tries to learn but is not hard once you figure out the rhythm. He said he does have to put some muscle into it and prefers a “running” mount to get the thing going.
I’ll try and get some video at next weeks practice.
It can be tricky to build up an eccentric wheel. A friend of mine was getting one built and had to give up after several wheel builders couldn’t manage the task (despite multiple attempts).
This is the kind of project that it is worth finding someone who has done it before to build the wheel for you. That way you will avoid the disappointment of having purchased the parts only to be told that your local bike shop guys can’t build the thing.
>What can people tell me about eccentric wheeled unicycles?
I have no info on the building or acquisition of an EWU. But I have a wee snippet of riding experience to share. I used to attend a unicycling club that was/is associated to Semcycle in the Netherlands, and the Semcycle people like to make one-off projects if they have some time on their hands.
October 2001 (in the unicycling club) I tried a 24" unicycle with an axle that was eccentrically placed in the wheel with moderate offset, axle 2 or 3 inches (just guessing here but certainly more than the 1" that Unibrier mentioned) off the wheel centre. I found it actually surprisingly easy to ride. Not good for speed though because of spontaneous jumping. Weird to get back to your normal wheel immediately after it: couldn’t ride it because my reflexes were biased!
I didn’t bring my tape measure but it looks like a 2" offset. He also has only 100-103mm cranks on it, they are definitely shorter than 125’s.
Norman makes it look easy but it is tough to ride. I only tried a couple times then Norman’s dad mentioned since it is radially spoked the wheel builder did not recommend adult weights on this wheel.
The first vid is him just riding it, in the second he is doing more exaggeration but not as much as he does in a show. It looks like he is riding almost one footed on the right foot, however it is the left foot that is doing all the work to get over the hump.
£££)
