had you considered that the shocks and springs from a bike would be far too stiff for this use?
if they were too soft the rim would squash and break
The problem with the first design is that however much travel you give it, it will rotate by up to that amount when you pedal, and wind up, when you stop pedalling it will unwind. You can actually buy some cheap nasty unicycles made like this. They don’t work because of the wind up.
To make a full suspension muni, you really need to make some kind of giraffe or equivalent cos the pedals need to not be fixed to the wheel axis.
yes, so you need to find a happy medium, and standard bike shocks won’t be it.
Also what Joe said, I’ve ridden one of those crappy 3 shock spoke uni bike things, altering the shock stiffness changes the ride from too stiff to make any difference, to too sloppy to ride in a straight line, with no middle ground.
i think i know just what your talking about
edit: i just drew this up like 5 minutes ago, its my idea for a suspensioned frame
You would have to have one of the shocks mounted solidly to reduce windup (able to completely eliminate :o )
The best working prototype I’ve seen. If you use 3 shocks + spokes like the second in there you wouldn’t taco the wheel, plus lighter and prob less expensive.
I don’t mean any of this in a sarcastic tone, I only mean it in more of a “I’m asking because I don’t understand” way. For all of the work (new frame, hub and wheel R+D), what’s the payoff once you ride as opposed to a standard muni? It may be a bit smoother feeling when riding offroad but will you be able to tolerate the associated consequences of a suspension frame? Also, most of your weight is on the pedals when you land so how will that force be displaced into the shocks?
see, in my system, the pedals arent connected to the hub directly, its seperated, the hub moves from in the frame, ive got so many bugs to work out still
ah, ok. that would be a bit different then. I’m no engineer, but do keep in mind that the “bottom bracket” type rigging you make for the pedals/cranks/spindle will need to be in a suspended state or you’ll still feel like you’re landing on solid unsupported ground
A recumbent I once used (Easy Racer Tour Easy) had some kind of suspension hub in the front wheel.
I wouldn’t call it suspension, it was more of a give that reduced impact on the handlebars.
It was pretty neat actually, but i really feel the only reason it worked was because so little weight is focused on the front wheel on long wheel base recumbents.
This suspension thing got me thinking and I came up with this.Basically it is a single pivot swingarm that could use mtb rear shocks.Chain driven on both sides because of split cranks.The chain length would remain constant through the suspension travel as the sprockets share the swingarm pivots.It would have a large Q factor to have room for the shocks.Would it be rideable and would it exhibit desirable characteristics with the cranks offset to the rear of the wheel.I dont know the answer to that ,I have no intention of building it but it doesn’t hurt to have a think about these things.
looks cool. Currently im working on fashioning out some plans for my chain driven idea, but like a midget girraffe on steroids, odd concept i think, and it’d end up weighing a bit, unless i can get half of it in aluminum
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It can be yours for $10 + shipping
Ahh but the holy grail for suspension uni’s is to have the cranks on the spongy side of the suspension.The picture in the link does no more than a suspension seat post.
I’d guess it would be better ridden the other way, with the pedals in front of the axle. This would make the riding position more natural (it would be pretty much like a bike, with pedals slightly in front of the saddle) and would also seem a better way for the suspension to pivot. It would be cool to build one just to see what it was like - it seems like it would be over-complicating things but look at the monstrosities of full-suspension bikes people ride! I must say I’m a bit skeptical that it would be better (or even as good as) a big low-pressure tyre though.
Somebody with the skills, time and resources needs to build one and see what it’s like - it would make a nice novelty machine if nothing else.
I thought about an alternative chain solution.
I wanted to make sure that the frame is still straight, so you still sit right on top of the axle.
The cranks are split like in dangerdog’s drawing. The frame is suspended between the axle and the cranks.
It may weight even more because you need 4 chains in total.
Just an idea
Dangerdog - That’s basically a simpler design of this
The closer the cranks are to the hub, the better the control would be, but the shock’s smoothness of action could be worse. A happy medium would have to be found.
Hugo - would probably work, but IMO one of the reasons why larger wheels are harder to balance on is the axle is higher off the ground.
Good ideas. Keep em coming!
Excellent drawing/photo but the challenge is to have the cranks suspended therefore it seems you have to have split cranks and some form of transmission from cranks to wheel so that the seat to cranks relationship remains constant and only the wheel travels up and down.Anyway your drawing/photo thingy looks great.
I just realized the pic I posted is basically a complicated suspended seat post only:(
I think yours is still full suspension though.
you could also stick some gears on that very easily
EDIT: I’m confused as to how the middle hub/axle part stays put, maybe you could draw a wheel around the image