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Old 2005-05-20, 04:52 AM   #1
gbarnes
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Another geared unicycle...

This has been operational since December. So far, so good.

http://www.public.iastate.edu/~gbarnes/gear_uni/




22 MPH and counting.
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Old 2005-05-20, 05:04 AM   #2
harper
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Cool design and beautiful package, George. So, 22mph and counting; how many miles and counting? Does the frame flex with the split axle or does the wheel axle keep it rigid?
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Old 2005-05-20, 05:07 AM   #3
john_childs
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Cool!
What's the effective wheel diameter?
How does it ride compared to a standard uni where the cranks are at the center of the wheel?
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Old 2005-05-20, 05:24 AM   #4
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Man George, that's excellent!

I must have watched the video clip 10 times.
Even the cow, in the background, looks stunned...
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Old 2005-05-20, 05:44 AM   #5
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harper - Thanks. Maybe 30 miles... I've been waiting for nicer weather. No detectable flex... anywhere. No backlash either.

JC - 2:1 on a 26" Hookworm, so around 54". It's a coker and a half! Unlike planetary hubs, I can change gear ratios pretty easily. For now this is plenty fast!

re: offset cranks - It's a bit goofy on the first go. After 3 practice runs it's just like normal.

roadkill - I think the cow was just cold It was about 20F for the test ride.
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Last edited by gbarnes; 2005-05-20 at 05:46 AM.
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Old 2005-05-20, 05:45 AM   #6
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A longer video clip of this road testing (with music and mediocre editing) is available (same clip, just different resolutions).

http://www.public.iastate.edu/~gbarn..._test_1048.wmv ~ 17 MB

http://www.public.iastate.edu/~gbarn...d_test_256.wmv ~ 4.5 MB
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Last edited by gbarnes; 2005-05-20 at 05:48 AM.
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Old 2005-05-20, 07:38 AM   #7
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I have seen this idea a few years ago. The build it on a 28 inch. I don't know where. I just find it by searching on google.

It is a cool idea.

But i think that you can't jump. Because your axe is not 1 piece. So you will probably breake your axes.

Maybe I'am going to build that on my 28 inch.

Than you will go quite fast.
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Old 2005-05-20, 07:42 AM   #8
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That's fantastic! So simple and solid looking.

Andrew
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Old 2005-05-20, 09:48 AM   #9
Albert Karel
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Re: Another geared unicycle...

Please manufacture one, George!

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Old 2005-05-20, 11:01 AM   #10
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Wow, really cool George!

You look so comfortable on it and in control.
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Old 2005-05-20, 12:29 PM   #11
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Out of curiousity, have you thought about making it a low rider (mounting the cranks below the hub)? Realistically, you won't be doing much offroading, wouldn't lower your center help some? How would changing the pivot at the center of the wheel effect the ride?
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Old 2005-05-20, 03:12 PM   #12
Mojoe
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George,

It's about time you showed this to the rest of the world.

The video rocks!

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Old 2005-05-20, 03:33 PM   #13
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Re: Another geared unicycle...


"gbarnes" <gbarnes@NoEmail.Message.Poster.at.Unicyclist.com> wrote in
message news:gbarnes.1pbdas@NoEmail.Message.Poster.at.Unicyclist.com...
>
> This has been operational since December. So far, so good.
>
> http://www.public.iastate.edu/~gbarnes/gear_uni/
>
>
>
>
> 22 MPH and counting.
>


The simplicity of design and what looks to be pretty robust looks good.
Not really for steep hills of course or for varying inclines, but for road
work excellent indeed.

Confession time: I didn't see the quoted speed at first, but being nosy I
did some calculations from the video. Silly waste of my time of course but
I did get similar numbers.

Good job G.

Nao




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Old 2005-05-20, 04:15 PM   #14
johnfoss
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Nice looking ride, George.
Quote:
Originally posted by Dirtsurfer
have you thought about making it a low rider (mounting the cranks below the hub)? Realistically, you won't be doing much offroading, wouldn't lower your center help some?
I was thinking the same when I watched the video. That wheel is probably too small for flipping the drivetrain, but it might work nice with a bigger wheel, maybe even a 29".

Of course the "budget" way to make one of these is to put the crank axle just above the tire, so you can use normal giraffe parts. Tom Miller used to make geared-up 20" unis like that, which he called Travelers. Like George's, you can change out the sprockets for different gearing (in the shop, not on the road).

With a Traveler design, you could also do what Walter Nilsson did on his cross-country ride in 1933. His giraffe had a different-sized bottom sprocket on each size, so he could change effective gearing by taking off the wheel and turning it around.
Quote:
How would changing the pivot at the center of the wheel effect the ride?
It's a giraffe. As you bring the pedals closer to the wheel axle it acts less giraffe-like, but that should be about it. Then with a geared-up wheel, you should get a little bit stronger gyroscopic effect, though this is offset by the unicycles' natural tendency to wobble.

I've never tried a unicycle with the pedals below the wheel axle. That would be different.
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Old 2005-05-20, 04:24 PM   #15
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Nice design.

All these geared unis... Must ask....
At what speed does a person have to tuck and roll out of a uni crash? How fast can a person run AND how fast can a person's feet go from pedaling to running at full sprint?

What new safety innovations will have to be developed for personal protective gear? How about a personal air bag? Fly off the seat and you turn into the Michelin Man and bounce to a safe stop. There is a test that would make a great video!

I'm not sure my body is ready to recover from a crash at 20+ mph. Are these geared unis going to be just for those who are willing to risk a high speed crash and related injuries?

I guess having a geared uni would be a benefit to people as myself, who don't want to risk a "high speed" crash, in that a common wheel size would allow more tire options. I love my coker, but tire options are quite limited.

Geared unis are trick and cool, but will they ever replace the big wheel?

Good work, George. My comments aren't meant to be negative. Just thinking out future needs and concerns. Hope it gets to production and you can make a few bucks making it.

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