Has this gone from trying to solve a problem to teaching a lesson? Do you know how to do it? And yes I finally see why the 2nd problem would still occur. I will have to ponder the 1st problem to convince myself it would happen when attached to a hub and a rim. I don’t see any answer to the 2nd problem. All the other problems I’ve been able to quickly come up with something. I am thinking I might have to ditch my approach to the parallelogram altogether.
What is your background cyberbellum? It seems as if you’ve done a lot of this type of stuff.
25 years of conceptual design engineering; aerospace, mechanical and computer science.
No, I haven’t got it completely worked out yet. And yeah, there is a bit of mentoring going on. You seem to have an interest in design so I thought you might appreciate a little feedback. It’s how all good ideas evolve. That’s why engineering design is usually done in teams. Really good ideas only appear after months or years of half-baked scribbling and experimentation.
So I’m curious - will this lead to a really useful device? It’s too soon to tell for sure but there are a few promising ideas in this thread. Time will tell.
I’m sorry, I have no engineering experience except for a class I’m taking now (I built an 8 oz. bridge of popsicle sticks that could hold 10 bricks). I’ve seen the pictures of the wheels with the shocks and springs, but what’s this parrallelogram stuff?
About a minute
I used fprime from www.worley.com for rendering.
Technically I think it still needs a few struts or something to help distribute the pressure that would be going straight into those rim hinges, definitely a few more spokes too (see latest render). I kinda think it’d work. I look at it as if the gazza is for absorbing the tree roots etc. and the suspension for absorbing drops, so the whole rotation thing wouldn’t be a prob, simply adjust the suspension to be tough enough to avoid that.
Wouldn’t be a great MUni for short ppl (like me) either because you have to have a lot of crown clearance. Maybe a different design of frame/seat post could help.
And yeah (theamazingmolio), I’m not sure if we did discuss the bit about the rigid hub but I’m starting to think 6 hinges would be better than 5 anyway. Not that 5 wouldn’t work, it’s just that I sense the cranks would be wanting to rotate by themselves when you did drops.
This is from a Trials expert who’s 15. The thing is, Bevan, you have a lot of suspension that will gradually fade away over the years.
For Trials, suspension would definitely only be in the way. But for cruising trails, which probably more unicyclists do, suspension can make the ride much nicer. A system that suspends your feet would make it easier to stay in control, or ride faster, over really rough surfaces, such as the “energy dampening field” in the 2001 NAUCC MUni race, if anyone experienced that. Riding perpinducular to what may have once been farm furrows. Ow!
But of course this is mostly an engineering experiment, and it’s all about figuring out a solution more than anything else. Even a nicely working design is likely to have such a tiny market, the cost of patent protection might not be justifiable.
And don’t worrry folks. I’ll start building a prototype suspended wheel at some point after I’ve updated my whole web site…
Having just posted the above, I just thought of a different approach for the suspended cycle. Using a chain type drive and conventional “fork” suspension might introduce problems on how to deal with the drivetrain when one end is moving.
So why use a front wheel suspension? It might also be possible to adapt an existing rear suspension design, to nave a non-vertical fork and something that keeps a chain the same length while flexing. It would still be heavy and might ride a little funny, but at least you could work with some pre-existing parts…
No, I don’t plan to build one of these either. If I ever get a rear suspension bike of my own, I’ll take it down some mountains just the way it is; without pedaling!!
If anything, I’ll restore the parts and rebuild my Excessory Cycle before Nationals. Don’t hold your breath.
Now I am by no means an engineer, but if you’re trying to suspend the wheel as it is rendered in the above picture, would not all the weight go to the axle, sink it down, and then you’d just be on a shorter version of the unicycle?
> Now I am by no means an engineer, but if you’re trying to suspend the
> wheel as it is rendered in the above picture, would not all the weight
> go to the axle, sink it down, and then you’d just be on a shorter
> version of the unicycle?
Since the springs need to be hard enough to handle hard drops, they
wouldn’t compress more than, what, 10% under bodyweight. Maybe twice
the under normal pedalling.
I have been wondering how much more often the cranks will hit the
ground with a suspension like this. That could be a real issue. It
would be nice to have a design that placed the crank spindle somewhat
above the center of the wheel and allowed it to drop just slightly
below.
On Tue, 25 May 2004 16:50:59 -0500, “johnfoss” wrote:
>And don’t worrry folks. I’ll start building a prototype suspended wheel
>at some point after I’ve updated my whole web site…
That sounds like a promise which I’m not sure you intend to make.
Maybe we should read after as “not before”?
Your ‘rear suspension’ unicycle idea has been proposed before, a.o. by
Andrew Carter. But I think the concept is intellectually not as
challenging, which I feel this thread is about.
Klaas Bil - Newsgroup Addict
be sure to remove the saddle and simply sit on the seat post. this is far more comfortable - tennisgh22 on the comfort of Savage unis
For Klass:
I only meant that building stuff like this is at a lower priority than redoing my web site. You’ve been around long enough to see how much I’ve done on that. But I guess it will happen someday…
Sorry, that would involve too much work. There are so many different rear suspension methodologies out there, surely one or more of them could be adapted to our needs as unicyclists.
Not sure what you meant by that. Was that something I said? For a rear suspension design, the frame would be something much more convoluted than just a vertical fork. Exactly what depends on the suspension system chosen. But the frame has to go somewhere other than just straight down to allow for the flexing.
As for the practicality of suspension, I understand the appeal of engineering something for the sake of being able to do it. I do that all the time. My math teacher hates me for it.
As for neccessity, suspension would be of no help to someone bombing over large bumps because no matter what the rebound would eventually reach your feet unless you had some serious dampening. This would throuw your feet around on the pedals and that only makes things harder. As for suspension on spots where it’s too flat and boring to stand up but too rocky to sit I tink suspension in the wheel wopuldn’t help that much. A seat-post shock would be more useful.
As for the engineering aspect, I think that the simplest technique to suspend the system is to have suspension in the crank arms. It’d feel a bit wierd, but I imagine it’d help if you want cheap and easy suspension.
As for another alternative, one could have something with chain-drive, so that there’s a fork holding the wheel and another fork hinged to this that goes points over the first fork to hold the cranks on each side so their axis of rotation is about the same as the wheel’s. Then, you have them run a chain out to the hinge of the forks and have a chain running back in to the hub of the wheel. Then, you can have suspension at the hinge. YOu can have the rest of the frame for the saddle come off the bearing holders for the cranks so the seat is also suspended.
Or you could simply make the spokes elastic and have a wobbly wheel.
I apologize for bringing this long thread up again, but I missed it last time and want to make a few points.
A quick summary of what has been said: people want to make unis with the suspension built into the wheel.
the basic Idea is clearly shown in the first diagram, and just looking at the other pics pretty much tells the whole story as to what’s been said so far.
As far as the whole parralellogram idea goes, I think the first idea without the parralellogram would work just fine, depending on how it’s used.
The problem illustrated here on page 3 would not be relevent, because the wheel would just roll forward a bit or backward a bit to relieve the stress at the hub, becaused it is hinged at the rim.
So the parellelogram and all it’s problems are not necessairy.
However you could overcome the slight rolling problem entirely and take some stress off by placing the telescoping “shock” perpendicular to the pedals.
That way the “shock” just compresses straight down.
I really like the elastic idea!! without dampening!!
Iwould buy one of those if i could afford it, and I think it would be a really good challenge to ride, even more so without extra lateral stability and lots of wind-up.
This thread started before I joined the forum so I had to read it. Wonderful ideas! Though one idea was not brought up: How about a second rim … and a second tyre? The second, smaller rim is placed inside the original one. Between these you have not exactly a tyre but only the walls of a tyre and inside … a tube! So this inner tyre placed inside the outer rim could be moderatly inflated to give some springiness while the outer tyre could remain hard so you can ride it with better control.
Using a fork that has shocks on each side of the fork, like the front suspension on a MTB. The seat is the only part that’d go up and down, but I would think you’d want the feet directly connected to the wheel.
As far as hopping goes on a fully suspended uni, through the tire or whatever, I would think it’d be hard to hop, because the suspension would soak up all the energy for hopping. Kind of like how a suspension bike isn’t good for doing tricks on, like wheelies or even trials, because instead of transferring the energy to the wheels and tires, the suspension takes it all up, and the wheels stay connected to the ground more. In order for the bounce to help you with height, like a pogo stick, it’d have to be really stiff, thereby canceling any comfort benefit of a suspension.
loosejello: it’s been done. It ended up not doing much, about as mucha as a seatpost shock, which is a semi-common thing.
the reason it doesn’t do anything is because it would only absorb shock on the seat, which there isn’t too much of in the first place. unless you’re my brother, who lands solely on his seat.
