This has been operational since December. So far, so good.
http://www.public.iastate.edu/~gbarnes/gear_uni/
22 MPH and counting.
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?
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?
Man George, that’s excellent!
I must have watched the video clip 10 times.
Even the cow, in the background, looks stunned…
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.
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/~gbarnes/road_test_1048.wmv ~ 17 MB
http://www.public.iastate.edu/~gbarnes/road_test_256.wmv ~ 4.5 MB
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.
That’s fantastic! So simple and solid looking.
Andrew
Re: Another geared unicycle…
Please manufacture one, George!
Wow, really cool George!
You look so comfortable on it and in control.
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?
George,
It’s about time you showed this to the rest of the world.
The video rocks!
Mojoe
Re: Another geared unicycle…
“gbarnes” <gbarnes@NoEmail.Message.Poster.at.Unicyclist.com> wrote in
message news:gbarnes.1pbdas@NoEmail.Message.Poster.at.Unicyclist.com…
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> This has been operational since December. So far, so good.
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> http://www.public.iastate.edu/~gbarnes/gear_uni/
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> 22 MPH and counting.
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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
Nice looking ride, George.
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.
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.
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.
Bill
I have tucked and rolled from a 20mph dismount with knee pads and a helmet. I was lucky and went down foot, knee, hip, shoulder, hydration pack, helmet, backward somersault. This ended up injury free.
14 to 15 mph is the max that I can expect to be able to likely run out a UPD and stay on my feet. I’ve run out a UPD at about that speed and stayed on my feet.
I experienced a Coker UPD at about 17.5 mph and ended up sliding on the ground in a superman position. I had inline skating kneepads and full finger leather cycling gloves on. I was sliding on the gloves and kneepads. No injury to me other than a minor scrape on my forearm from the pavement. I don’t have very good instincts to go for a tuck and roll. That’s why I ended up in the superman position sliding on the ground. The protective gear did its job.
At 17.5 mph I was able to get one foot on the ground and then the second foot on the ground in an attempt to run it out. But I can’t move my legs that fast and the attempt at a run out was futile. One foot, two foot, superman dive (or a tuck and roll if you have the instinct).
One potential problem with the geared unicycles on smaller wheels is that your feet are closer to the ground than with a Coker. With your feet closer to the ground you’re not going to have as much time to get your feet into a running position during the first part of the UPD. It will probably be more difficult to run out a UPD on a smaller wheel where your feet are closer to the ground. George’s geared uni looks like the pedals are actually a little bit higher than a Coker.
If I look at the frame photo I see four problems with that idea.
1.) It appears that the crank axis to axle axis distance is about 6" or a crank length. For a moderate sized wheel the design would exclude people who don’t have that extra 6" of inseam. Actually, 12" of extra inseam going from one design to the other would be required. George has it and wouldn’t care, though.
2.) The crank axis would be close to the ground and with a small enough wheel some serious pavement strikes could be made on the pavement with the pedals during a turn.
3.) Hanging the cranks off the bottom eliminates the additional top support strut (the crown) in the frame so it would be more likely to flex.
4.) The chain tensioning mechanisms would suddenly become much more complex.
These problems exist but it doesn’t mean that they can’t be overcome or some compromises can’t be made. You should build one.
After all the quotes and stories about the great JC and unicycles, I would expect that you would literally fly away Superman style. My uni-hero may be mortal… Oh No! Sorry JC, but you don’t get many style points for flying that low to the ground.
The stories from you and Harper are making me think that I might go for another speed attempt on my coker. I’ve hit 16+ a couple of time but it would be fun to bump that up a little. It will definitely be a full gear attempt if done. Maybe a fall or two won’t stop me from going to work the next day.
Bill
Wow, that would be a very odd feeling wouldn’t it? When you lean (or loose your balance) forwards, your feet would be sent backwards…very odd.
Couldn’t you stick something between (and connected to) the two chain rings to reduce flex?
Andrew