Geared hub unicycle

[showard]

This past weekend I was graced with a visitor from the Pacific Northwest
- none other than Mr. Harper, the inventor of the uni.5 and Blue Shift
geared hubs. My house was his first stop on a cross country journey to
NAUCC - driving a car completely loaded with unicycles of all kinds.

We've colaborated a little bit on the design of a geared unicycle that,
hopefully, will be available in the near future at a reasonable cost.
My part of the project is the frame and Harper's part is, naturally, the
hub.

Last week Harper received some sample frame parts from the overseas
manufacturer so he sent them to me along with a prototype hub, also
manufacturered overseas, so I could check them out and make sure the
frame was what I had in mind and that the hub fits the frame.

I wanted to try and assemble the parts into a ridable geared hub
unicycle before Harper arrived Friday night. I was able to get a 29"
wheel laced to the hub and hub guts installed by Friday. Saturday
afternoon (after a morning MUni ride where Haper showed my how MUni is
REALLY done) we finished putting the frame together, installed the tube
and tire, cranks, seat, etc. and took it for a spin around my
neighborhood.

I put 170mm cranks on it mainly because that's all I had available to
use but I also had the idea it would make the thing easier to ride in
43.5" mode. Harper took the first ride and said that it was "10,000
times easier to ride than Blue Shift" with the long cranks. I thought
that was an exaggeration though ... it only seemed several hundred times
easier than what I recall about riding Blue Shift with 150mm cranks.

Harper rode the new geared hub uni and I rode my non-geared 29'er along
a paved bike path. I was pedaling like a demon while Harper was just
loafing along. The plan was for Harper to ride the geared uni "out" and
I'd ride the geared uni "back". Unfortunately it broke ... a weld
failed on the frame ... so we both got to walk "back". Oh well - that's
what prototypes are for and I'll have it fixed and ridable again this
week.

The attached picture is Mr. Harper with the new geared hub uni on his
right and my 29'er on his left.

Steve Howard


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[Eublapharis13]

That looks Awesome!


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[paco]

So, any secrets as to how it works? Is there a chance of getting a nice
portable 20" geared to 36"? When you say 'reasonable cost,' is there a
ballpark figure of what that means?
That sounds like a great idea. I hope it works, 'cause the world needs
a good geared uni!


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[jason]

Steve:
Your frames look really nice. It's a shame you didn't get to ride back
but at least it was the frame and not the reproduction hub that broke.

Greg (on the road):
Had you ridden on the 'overseas' prototype hub before Steve laced it to
a rim or was this your first go at it? Also, does this mean that you're
close to relasing a production epicyclic hub equiped uni? Steve, maybe
you can answer this since Greg's out on the open road?

Paco:
Harper's Epicyclic Hub (link):
http://tinyurl.com/hmsa


Cheers,
Jason


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[universacycle]

To change gear, I guess you have to stop riding and get off? Does it
require tools to change the gears? How (basically) do you change the
gears?

-Hugh


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[john_childs]

universacycle wrote:
> *To change gear, I guess you have to stop riding and get off? Does it
> require tools to change the gears? How (basically) do you change the
> gears?
>
> -Hugh *

You do need to dismount and fiddle with a bolt to change the gear.

There is a short lever arm that is part of the hub. When the end of
that lever arm is connected to the frame the hub is geared to 1:1.5.
When the lever arm is disconnected from the frame (and bolted in place
to the hub itself) the hub is in a 1:1 gear. Changed the gear is a
matter of removing a bolt, positioning the lever arm in its new
position, and putting the bolt back in. It takes a minute or so to
change the gear. With practice you can get faster at the gear change
process.


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[john_childs]

Oh, and there are pictures of Greg's original version of the Uni.5 hub
in the gallery.
<http://gallery.unicyclist.com/albun23>
You can see the lever arm on the hub and how it bolts to the frame to
put the hub in to the high gear.

The hub that is being made overseas is slightly different in design but
basically the same.


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[showard]

The geared hub uni is Harper's thing so I don't know anything about cost
or when they'll be available. I think the hub is very close but the
frame has some problems that still need to be worked out.

Greg made two epicyclic hubs - one was built into a 24/36" uni dubbed
"uni.5". His other hub is what Blue Shift is built around. The hub and
frame I have are the first overseas version that have been assembled
into a ridable unicycle. The big difference between Greg's first two
hubs and the new one I have is that the new one can be disassembled
without having to remove the spokes. That's a good thing! Other than
that it's just the same as the original version.

As John explained, the hub is shifted by changing the position of a
screw. The question that has been asked before is "can a hub be made
that will shift on the fly?" Anything is possible but shifting a
unicycle hub on the fly is a very difficult problem. One of two things
*must* happen when changing gears. Either the hub must be completely
stopped while BOTH ratios are momentarily engaged (thus locking the hub)
or the hub must free-wheel BETWEEN the two ratios. Either one would be
a problem on a unicycle. I'm sure someone somewhere could learn to
shift a unicycle while it freewheels but ...

Another problem with a shift on-the-fly unicycle would be shifting gears
in the rider's brain. The difference between 29" and 43.5" modes is
dramatic. I find it takes some time to get used to the difference after
shifting the hub. Again, someone, somewhere could learn to deal with
the instant change in ratio but I'm not sure I ever could.

Naturally, shift on-the-fly would make the hub more complicated and
expensive to make too.

Steve Howard


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[Borges]

This thing is already on the 4 first places on my wishlist.

Tell me more! Tell me more!:

As far as I remember there was once a problem with a bent axle on uni.5.
Will the new hub be stronger or do you just have to be carefull with
it?

Is it possible to use the hub with other frames?

Will other framesizes be available?

Does "hopefully, will be available in the near future" mean that it
might become available or that it will definately become available at
some point?


Morten


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[UniBrier]

Borges wrote:
> *As far as I remember there was once a problem with a bent axle on
> uni.5. Will the new hub be stronger or do you just have to be carefull
> with it?*
I'm sure Harper will run the prototypes through the gauntlet to be sure
they hold up.
Borges wrote:
> *Is it possible to use the hub with other frames?
>
> Will other framesizes be available?*
The 29er frame has a hole machined for the fixing bolt. The original
uni.5's Torker frame was just drilled in the right place. I have no idea
what the plans are for frame sizes but unless you plan on gearing up a
Coker the 29er frame should accomodate all the other wheel sizes.

Check out Greg's lame web page too:
http://staff.washington.edu/gharper//


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[harper]

The hub by itself would probably fit most unicycle frames. It is about
1/8-1/4" wider from bearing center to bearing center and most main cap
bearing frames are somewhat forgiving along the axle. Those frames could
use the production hub and be strapped to run in 1.5 gear mode full time
rather easily. The frame that will accompany the production hub has
holes bored in strategic locations to relatively high tolerances that
will make it easy to shift from one mode to another. This is the way
Blue Shift is made. It also has machined bearing holders and, as such,
must fit the axle to length quite closely.

The bent axle on the original uni.5 hub was made of 1018 or 1022 soft
steel. The latest oversees prototype that I received was made of heat
treated 4140 Stainless hardened to Rockwell C-37. I think it is hard
enough to accept any steel cranks and tough enough to resist bending and
twisting especially since the primary use is as a road unicycle, not a
MUni or trials rig.

The weld that broke on the prototype frame connected the seatpost tube
to the crown. When Steve and I looked at the frame before it broke we
agreed that the weld was unnecessarily stout. Little did we know that it
would be the point that failed. Had the manufacturer adhered to Steve's
tolerances, the tube would have been a nice, tight press-fit into the
crown. After the weld broke, it was clear that this fit was sloppy and
the only thing holding the pieces together was the weld itself...not
good practice. The frames that Steve has made himself are not welded at
all but use the press fit and a roll pin to anchor the parts. I have had
no trouble with either of his frames that I own.

Meeting Steve and staying at the Howard household was a real treat and
only serves to reinforce my belief that unicyclists are the finest of
folks. The Howards were kind, generous, and tolerant hosts. Especially
Brenda who had to accommodate the first of perhaps many eccentric
"loony-cyclists" who make the pilgrimage to Pocatello, Idaho, the home
of Kinport Cycles. Fortunately for me, Steve has no local riding
partners so all I had to do to look good was any one thing on his "home
court" trail that he couldn't do. I just showed him how to handle the
flat parts.


--
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-Greg Harper

B L U E S H I F T

"Are you OK???" - Just about anyone I've ever ridden with

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[paco]

I agree that Steve is an excellent human being. He was very helpful in
building my MUni, and saved me a LOT of money!
So Harper, what is different between your new hub and the Blue Shift?
Why is it so much easier?


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"We are all interested in the future, for that is where we will spend
the rest of our lives."
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[carjug]

Wow, I bet one of those hubs would be great on a Coker!


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[unisk8r]

I understand alot of folks (including Mr. Harper) are in Moab this
weekend, but is there anything new to report on this most intriguing
project?


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[vivalargo]

carjug wrote:
> *Wow, I bet one of those hubs would be great on a Coker! *


I second that motion, though a 50% speed increase while Cokering is a
frightning, but exciting, proposition. Imagine a cruising speed of
22MPH?! Might have to start riding in full leathers . . .

JL


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[GILD]

vivalargo wrote:
> *Might have to start riding in full leathers . . .*
u say it like it's a bad thing!
:cool:


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GILD - Waffle-tosser (ocfopgm)

'They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.-- Benjamin Franklin,
HistoricalReview of Pennsylvania, 1759
' (http://www.soaw.org/new/newswire_detail.php?id=413)'[image:
http://www.addis-welt.de/smilie/smilie/sp/84255.gif]'
(http://tinyurl.com/ywxgb)'what's this?'
(http://www.outwar.com/page.php?x=2055415)



Namaste!
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[tom_edmonds]

would take the whole unicycle gang issue to a new level.


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[north]

ok... changing the subject slightly... can these hubs freewheel? and if
not is it possible to make a freewheel hub and is anyone planning to do
it?


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[GILD]

north wrote:
> *can these hubs freewheel? and if not is it possible to make a
> freewheel hub and is anyone planning to do it? *
> -North's self-chosen forum title -
> *Circus Trick ******* *


makes sense now
:p


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-ORIGINALLY POSTED BY A FELLOW UNICYCLIST IN A MOMENT OF SUBLIME
INSIGHT-

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topic whether 'significant' or 'other' is the defining word in that
phrase."
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Namaste!
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[uni412]

Not to be ignorant, but wouldn't it be a lot easier (and I think just as
efficient) to make a unicycle with adjustible-length cranks? Has someone
ever done this?


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[mscalisi]

uni412 wrote:
> *Not to be ignorant, but wouldn't it be a lot easier (and I think just
> as efficient) to make a unicycle with adjustible-length cranks? Has
> someone ever done this? *


easier, perhaps. In fact, adjustable-length cranks exist (although VERY
expensive).

As efficient? I guess that depends on how comfortable and capable you
are of pedalling at a very high cadence.

Actually, now that I think about it. Why would you want to choose? How
about a geared-hub unicycle with adjustable cranks!!

I got to try the geared uni at Moab. I only rode it for a few minutes
and it was very difficult for me until I "mentally shifted". The bottom
line: I want one! I like the idea of flying down the street without
petalling frantically.


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[HandyAndy]

> ok... changing the subject slightly... can these hubs freewheel? and
> if not is it possible to make a freewheel hub and is anyone planning
> to do it?

the Harper hub does not freewheel, and yes it is possible to make a
freewheel hub, 'this'
(http://www.unicycle.com/shopping/shopexd.asp?id=439) one is not geared
but would work with a unicycle. also, that's how the old 3 speed
bicycles worked, there are a number of companies still making internal
gear bicycle hubs that of course freewheel ('if you want to wrap your
mind around something check out what NICOLAI is doing'
(http://tinyurl.com/2mdl7) ) but that would require some modification to
adapt to a unicycle.
> Not to be ignorant, but wouldn't it be a lot easier (and I think just
> as efficient) to make a unicycle with adjustable-length cranks? Has
> someone ever done this?

this has been brought up before, Steve Howard (showard) has a design
that he brought up a few months back, a search should find that. he also
has a couple CAD drawings in his 'gallery'
(http://www.unicyclist.com/gallery/cranks)


--
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[danger_uni]

vivalargo wrote:
> *
>
> I second that motion, though a 50% speed increase while Cokering is a
> frightning, but exciting, proposition. Imagine a cruising speed of
> 22MPH?! Might have to start riding in full leathers . . .
>
> JL *


All going well, I'll be riding one of these pretty soon! Can't
wait!!!!

Kris Holm.


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[U-Turn]

danger_uni wrote:
> *
>
> All going well, I'll be riding one of these pretty soon! Can't
> wait!!!!
>
> Kris Holm. *
Hmmmm.... Bonneville Salt Flats?


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[fluffinator007]

Any idea when they will be open to a guy, like me.


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[elmer]

Or how a bout a Coker geared down to go slower? You'd have the wheel
that rolls over anything and the torque to actually do it, if you could
maintain balance.


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[TheBadger587]

Does this mean that it is possible to have future unicycles shift gear
while riding and freewheel? imagine that- it'd be just like a bike, only
with mandatory balancing abilities.


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TheBadger587 - Level 4

Well i Guess not the retarded ones... but how could you even say
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[HandyAndy]

okay, about that adjustable crank idea, i sait it was showard but i was
wrong it was onewheeldave in 'this thread' (http://tinyurl.com/2plgy)
that i was thinking of, the CAD drawings are showard's tho.
> Does this mean that it is possible to have future unicycles shift gear
> while riding and freewheel? imagine that- it'd be just like a bike,
> only with mandatory balancing abilities.

have a look at 'this thread' (http://tinyurl.com/2b2yh), it covers that
very topic at some point (this was one i was thinking of earlier but
could not find then)


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[Klaas Bil]

On Fri, 2 Apr 2004 21:46:15 -0600, "elmer" wrote:

>Or how a bout a Coker geared down to go slower? You'd have the wheel
>that rolls over anything and the torque to actually do it, if you could
>maintain balance.

Has been brought up before. But a) an internally geared hub would
probably not stand up against MUni abuse, and b) you loose quite a bit
on manoeuverability and agility, compared to a more regular MUni.

Klaas Bil - Newsgroup Addict
--
I think profile should make some stronger 145mm cranks - Ryan Atkins

[shadowuni]

i ~will~ put one of these on my coker, and i want to know about when
they will be available, and about how much they would cost. thank you.


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[rob.northcott]

Just a thought - I'm sure somebody has already considered this, but
still...

Make the hub with the epicyclic gears permanently engaged (with the arm
permanently attached to the frame), then have two clutches (actually
would be more like two drum brakes) that would lock the axle to the hub
body in one position (1:1) and the outside of the epicyclic mechanism to
the hub in the other position (1:1.5 or whatever). Obviously the
brakes/clutches would have to be set up so that there was a moment
during the shift where neither gear is engaged (i.e. freewheel) to avoid
locking up, but this would be a very short time if shifted quickly.
Using clutches like this would avoid the problem of having to engage
teeth and ought to be shiftable on the fly using a cable and bike-type
gear lever under the saddle.

So, what's the catch? Too complicated/expensive? Too big/heavy? Too
weak? What I see in my mind is inspired by a combination of car
overdrive and bike drum brake...

Rob


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[GILD]

mmm, can't wait for the techies to get here...


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[Mike Roberts]

> Make the hub with the epicyclic gears permanently engaged (with the arm
> permanently attached to the frame), then have two clutches (actually
> would be more like two drum brakes) that would lock the axle to the hub
> body in one position (1:1) and the outside of the epicyclic mechanism to
> the hub in the other position (1:1.5 or whatever). Obviously the
> brakes/clutches would have to be set up so that there was a moment
> during the shift where neither gear is engaged (i.e. freewheel) to avoid
> locking up, but this would be a very short time if shifted quickly.
> Using clutches like this would avoid the problem of having to engage
> teeth and ought to be shiftable on the fly using a cable and bike-type
> gear lever under the saddle.

Now, I have never actually unicycled before (I've been reading this
newsgroup in order to learn about them before I buy one), but it seems
like there would be a big advantage to being able to disconnect the
wheel from the pedals, in order to coast, and have wondered if there are
unicycles with clutches. If it were possible to coast and stay upright
and on the unicycle, this method would be a really good way to do it.

[rob.northcott]

The problem with freewheeling on a unicycle is that normally the
forward/backward balancing is done by the pedaling action - without the
drive it's very hard to stay on. Some people have built unicycles with
freewheeling hubs and can ride them, but in normal circumstances it's
not a good thing.


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[Mike Roberts]

rob.northcott wrote:

> The problem with freewheeling on a unicycle is that normally the
> forward/backward balancing is done by the pedaling action - without the
> drive it's very hard to stay on. Some people have built unicycles with
> freewheeling hubs and can ride them, but in normal circumstances it's
> not a good thing.

I suppose if you were able to adjust the friction on the freewheel very
accurately, it would be <i>possible</i>, but I bet it would take a
rather large amount of practice to get the hang of it.

[Roger Light]

Mike Roberts wrote:
> rob.northcott wrote:
>
> > The problem with freewheeling on a unicycle is that normally the
> > forward/backward balancing is done by the pedaling action - without the
> > drive it's very hard to stay on. Some people have built unicycles with
> > freewheeling hubs and can ride them, but in normal circumstances it's
> > not a good thing.
>
> I suppose if you were able to adjust the friction on the freewheel very
> accurately, it would be <i>possible</i>, but I bet it would take a
> rather large amount of practice to get the hang of it.

I rode a small one at the Uni-meet at Kidderminster here in the UK last
month. It does take some getting used to, but the hardest bit is getting
on I'd say.

Fantastic fun though.

Cheers,

Roger
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[lleberg]

I'm still waiting for the unibike, the motorbike with one wheel only.
:cool:


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[underdog]

I never cease to be amazed at how a thread that started a year and a
half ago can be revived. Anyway, being a motorcycle enthusiast, I'm
with Ileberg on the unibike thing.


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[Klaas Bil]

On Wed, 3 Nov 2004 05:51:41 -0600, "rob.northcott" wrote:

>I'm sure somebody has already considered this

Haven't heard of it yet.

>Make the hub with the epicyclic gears permanently engaged (with the arm
>permanently attached to the frame), then have two clutches (actually
>would be more like two drum brakes) that would lock the axle to the hub
>body in one position (1:1) and the outside of the epicyclic mechanism to
>the hub in the other position (1:1.5 or whatever).

It's a nice idea, and as Mike Roberts pointed out, the option to coast
is a nice extra. Another extra is that you have a brake, if the two
drum brakes can be operated independently. And if they are, you can
also determine yourself how much 'coasting time' there is while
switching gears. I don't know how technically feasable this whole
thing is though.

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[Klaas Bil]

On Wed, 3 Nov 2004 14:01:35 -0600, "lleberg" wrote:

>I'm still waiting for the unibike, the motorbike with one wheel only.

Look at the Bombardier Embrio, e.g. at
<http://www.gizmohighway.com/transport/bombardier-embrio.htm>. But
indeed you'll have to wait...

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[rob.northcott]

Klaas Bil wrote:
> * Another extra is that you have a brake, if the two
> drum brakes can be operated independently. *


That's a good point - I hadn't thought of that... if the two
brakes/clutches are both partially engaged it would act like a brake. I
would imagine the control linkage would get a bit complicated though -
could have two cables, one for each brake, then the brake lever would
have to operate them both in the same direction while the gear shift
lever needs to operate them in opposite directions. Could possibly work
if the gear lever was mounted on the end of brake lever. Hmmm... Could
get horrendously complicated - both to build and to ride :)

Rob


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[Klaas Bil]

rob.northcott wrote:
> *
> That's a good point - I hadn't thought of that... if the two
> brakes/clutches are both partially engaged it would act like a brake.*
I think it's easier than that. During normal riding one of the brakes is
already fully engaged (blocked) - which one depends on the chosen gear.
I imagine that the lever is somehow (for the time being) fixed in the
fully engaged position. Now when you want to brake, keep that one fully
engaged, and operate the other lever to the degree that you want to
brake.

Klaas Bil


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[rob.northcott]

Ahh, so you see it as having two separate gear levers, one for each of
the brakes, so when one gear was engaged the other lever could be used
as a brake? Sounds good in theory... but would manipulating two levers
to change gear be too taxing (of course, at the same time having to cope
with the change of gearing without falling off!)?

I suppose you could have the two levers next to each other so that one
is engaged when back and the other is engaged while forward. Then to
change gear the rider would just grab both levers and move them
together, then braking would be done by fiddling one lever only (but it
would have to be the correct one depending on which gear is selected -
the other one would introduce slip rather than braking).

Sounds interesting, but unfortunately I don't have the equipment or
skills to build one and see what happens, so it'll probably stay as
theory (unless one of you engineer types wants to make me one ;)) Could
get expensive as a one-off I imagine.

Rob


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[Klaas Bil]

rob.northcott wrote:
> *would manipulating two levers to change gear be too taxing (of
> course, at the same time having to cope with the change of gearing
> without falling off!)?*
Not more than (in a manual-shift car) operating the accelerator, clutch
and gearstick in a coordinated fashion (of course, at the same time
having to cope with traffic around you).

I think the idea has potential but I'm far too un-techie to give it a
go.

Klaas Bil


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[harper]

I'll start and stop with the most obvious problem. Where do these cables
run? Do they come out the axle? They would have to in order to keep them
from tangling in the spokes or frame. Where do they go from there, do
you just hold them or do they loop around your legs and back onto the
frame? Remember, on a unicycle there's a pedal and a crank that has to
go around on both sides of the axle. On a bicycle that's not the case
because it's chain driven and the axle is stationary. Does the cable
rotate with the axle? There has to be some running surface inside the
hub and outside the axle so the cable doesn't twist constantly. Where do
you put all this stuff? Then you have these two cable loops, one on each
side, trying to snag anything they can find on either side of you.


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[rob.northcott]

I've been thinking about this and realised that the problem is how to
connect the levers/cables - I knew there ought to be a catch :(

I see Harper has already beaten me to it by posting this fact - I'm glad
it was you who noticed this - I imagine you must have done plenty of
research into this type of thing before coming up with your design,
that's why I expected my ideas to be shot down straight away!

I think it COULD be done in theory by having some sort of sliding
collar/trunnion arrangement so the cable wouldn't have to come out in
the middle of the axle, but that would necessitate some sort of
ridiculously complicated concentric bearing-inside-bearing that would be
pretty much utterly impractical.

Harper - I hope you don't think I was trying to suggest I could do
better than your design... it's just that the discussion about it got
me thinking about things. The tone of my post was intended to be "why
is this a stupid idea?" rather than "this is how it should be done".
I'm always a pessimist - there's (nearly) always a catch, and Sod's Law
always prevails :)

Rob


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[rob.northcott]

Sorry about the double post, but I couldn't resist this... please take
it as pretty much tongue-in-cheek ;)

Firstly, the "cranks in the way" problem could be got round by making it
a giraffe - a 20" wheel giraffe with the bottom bracket only just above
the top of the wheel wouldn't be that much higher than a coker.

Another way round the linkage problem would be to operate the clutches
with solonoids inside the hub, then there is no need for a mechanical
link from the outside to inside of the hub, and the electrical
connections would be easily done using brushes. Of course you would
need to carry a battery to operate all this, and using solonoids would
make it all less controllable (each clutch would be either engaged or
disengaged, ruling out the braking/slipping features)...

Sorry, I'll shut up now.:D

Rob


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[harper]

rob.northcott wrote:
> *
>
> Another way round the linkage problem would be to operate the clutches
> with solonoids inside the hub, then there is no need for a mechanical
> link from the outside to inside of the hub, and the electrical
> connections would be easily done using brushes. *


Why use the brushes? The magnetic fields will easily penetrate an
aluminum hub that's not rotating too fast. That way you can keep the
coils on the outside.


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[harper]

rob.northcott wrote:
> *
> I imagine you must have done plenty of research into this type of
> thing before coming up with your design, that's why I expected my
> ideas to be shot down straight away! *


On the contrary, I like seeing ideas like this develop, not shoot them
down right away. Just because I don't see how it would work doesn't mean
it can't be done somehow. Bendix used to make a shiftable, two-speed
coaster brake hub that you shifted by back pedaling slightly. It's
inappropriate for use on a unicycle but the clutch, gear, and brake
mechanism is all contained in the hub with no cables coming out of it at
all.

Klaas will figure out how to do it with petroleum eventually. Ow. My
tongue is buried so deeply in my cheek it hurts.


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[juergen_brauckmann]

harper wrote:
> *
> Bendix used to make a shiftable, two-speed coaster brake hub that you
> shifted by back pedaling slightly. *


F&S had a fully automatic hub that worked with flyweights.

<http://tinyurl.com/49bcm>

The flyweights moved a metal disc that engaged a different pawl and
ratchet system for slow and for high speeds.

I also own an old Shimano hub that has automatic shifting with
flyweights.

Still not usable for unicycling because of the pawl/ratchet mechanism
(=freewheel), but a very interesting design.

Regards,
Juergen


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[joemarshall]

If you were to run cables down the frame, would it be possible to
connect them to the hub using a mechanism similar to a gyro on a bmx?
Basically it's a thing that lets you do bar-spins all the way round and
never get tangled cables. I'm not sure how it works though. It doesn't
seem to add massive drag to the bars, but I assume adds some.

Joe


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[rob.northcott]

Yes I think you probably could use that type of linkage. In a unicycle
hub application the mechanism would have to have proper bearings because
it is constantly moving and we don't want it to wear quickly or add too
much friction to the wheel, but it sounds like it should work. Might be
a bit fragile though - there would have to be at least two (preferably
three for stability) sliding pins poking out of the hub and attached to
the inner disc of the "gyro" as Joe called it (I'm not sure of the
terminology but I know the BMX brake linkages he means), which could be
quite prone to damage, although they could be protected by some sort of
guard.

Rob


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[north]

ok, i know for a fact there are one or two of these things in existence,
but there has been a lot of talk and not much action..
instead of trying to develop clever gear change systems, wouldnt it be
more sensible to start at the beginning and produce a simple one gear
unicycle hub? no changing needed or existing.. then develop from
there?
it would improve street riding if nothing else...


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North

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[rob.northcott]

north wrote:
> *there has been a lot of talk and not much action..*

As far as I understand, Harper is having a batch of hubs made to his
design and has already had the test one(s) back.

> *instead of trying to develop clever gear change systems, wouldnt it
> be more sensible to start at the beginning and produce a simple one
> gear unicycle hub?*

That's what Harper's design is if left locked in the "geared" position -
it already exists, although not in mass-production (yet) and probably
quite costly at the moment.

What I've been posting about was just inspired by people's comments that
it would be good to be able to change gear on the fly, like on a bike,
and the problems of doing that with a unicycle hub. I don't expect
anybody ever to build something using these ideas, because although I
believe it to be possible in theory it would be horrendously complicated
(thinking about it more, the solution mentioned above using BMX gyro
linkages would involve slipping rings both inside and outside the hub at
least for one of the two clutches) and therefore probably unreliable,
very expensive or both. It's just fun to think about the possibilities
:)

Rob


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[north]

it cant be impossible tho.. cos there are internally geared mountain
bike hubs which it can be done one... the only difference is that drive
comes from a rotating axle rather than a sproket on a fixed axle...is
there any information on harpers hubs? and i recently heard there was a
swiss (i think theyre swiss) company whod developed one and were ready
to mass produce... any one no anything about that?


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[GILD]

north wrote:
> *i recently heard there was a swiss (i think theyre swiss) company
> who'd developed one and were ready to mass produce... any one know
> anything about that? *
check 'this thread' (http://tinyurl.com/5r9b6)


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[Klaas Bil]

On Thu, 11 Nov 2004 07:37:04 -0600, "GILD" wrote:

>check 'this thread' (http://tinyurl.com/5r9b6)

And when you're done with that, this one:
<http://www.unicyclist.com/forums/showthread.php?s=&threadid=36100>

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[wilsondesign]

Hi there , that's a nice and clean frame design. I just finished a
unicycle design project for my Senior project at San Jose State
University. I'm now a professional Industrial Designer and would like
to get into designing unicycles. Anyone can reply, I have a great Uni
project concept that I can show. thank you Allen



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[vivalargo]

wilsondesign wrote:
> Hi there , that's a nice and clean frame design. I just finished a
> unicycle design project for my Senior project at San Jose State
> University. I'm now a professional Industrial Designer and would like
> to get into designing unicycles. Anyone can reply, I have a great Uni
> project concept that I can show. thank you Allen
>



Show it. Post a pic.

JL


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