Geared 36

here's a closeup of the transmission

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and from the front:

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And for what it's worth, I'm calling this a Geared 36", 'cause the only
Coker product is the tire (not even the tube). I don't see why we keep
referring to these as Cokers, some day there will be another tire choice
anyway... My .02

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Very very nice...How was the ride?

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You should paint it green. Green is the color of envy. 🙂

It will be interesting to find out if it rides better than the
internally geared hubs like the Uni.5 and the Schlumpf hub. The
jackshaft drive type of gearing definitely has potential. The other
advantage with the jackshaft gearing is that you can gear it higher than
you can with an internally geared hub.

Now we need some fast riders to come to Seattle and try to break the 1
hour distance record and the 100 mile speed record using your unicycle.
🙂

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"unisk8r" <[email hidden]> wrote in
message news:[email hidden]...

Quoted message said:

And for what it's worth, I'm calling this a Geared 36", 'cause the only
Coker product is the tire (not even the tube). I don't see why we keep
referring to these as Cokers,

That seems very reasonable to me: to call that a coker would be very
misleading, or more probably an untruth. You might be tempted to conjure up
your own brand name, to be applied to the genre of all unis following the
pattern. A KH unicycle is merely a (good) modification of a standard
pattern, yours deserves a wider recognition, in the way that Blue Shift now
defines that particular geared unicycle . I think your gearing concept
would be a nice addition to a smaller wheeled machine, if it could be done.
It looks a mean machine and I like it, especially how, with the double
gearing, the pedal axis remains in line with the wheel centre. Nice simple
concept, not sure how difficult it was to fabricate. Look forward to
hearing some road reports.

Nao

This may be the machine to conqor the Marymoore Velodrome. Maybe you've
heard of the place.🙂

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I love the design.

What I can't figure out is how the two cranks manage to stay in sync.
Is there another gear system on the other side, or are the two cranks
connected directly? Or is there something else I don't see?

Great job!
Daniel

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daino149 said:

*I love the design.

What I can't figure out is how the two cranks manage to stay in sync.
Is there another gear system on the other side, or are the two cranks
connected directly? Or is there something else I don't see?

Great job!
Daniel *

Pete is going to have to explain the details of the design.

The basic design is that the hub body is on bearings and rotates around
the spindle. It is a one piece spindle and the cranks attach to the
spindle. That keeps the cranks in line. The trick is that the hub body
is on bearings and is able to rotate faster than the spindle.

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unisk8r said:

For the past 8 months one of my fabrication projects has been a geared
36".

Great concept! I notice two chain tensioners. Can the tensions be
adjusted separately without the drive getting out of true? Maybe that
is not needed because both are 22/18.

You probably have to adjust chain tension to hit a compromise between
friction losses and backlash, maybe you can comment on that?

Klaas Bil - Newsgroup Addict
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I used twin dropouts and chain tensioners ala giraffe. Only here there
are 2 chains. In a perfect world, there would be no chainline issues.
But here, even though I did my best to get the cog separation on the
jackshaft equal to the separation between the hub and the crank cogs, it
seems that so much tension is required to avoid crank play, that the
stress results in a ever-so-slight bend of the jackshaft housing. Those
that have peered down the chainline of a giraffe know what this means.
You want it perfect. I think this arrangement is fine, and I suspect
that the inferior chain has more to do with the necessary tension than
the cogs. I've adjusted so much tension that there's friction at the
wheel.

As for the ride, I will confirm Harper's and Childs' assessment that it
is less forgiving. I think that because your inputs are magnified at
the wheel due to the gearing, that you have a smaller "sweet spot" of
controllability. Crank length is definitely much less of an issue. I
think it will just take practice to "get the feel" of it. But it's
definitely smoother overall than a direct drive, and the lower cadence
was a big motivator for me; I still don't spin well!

I'll report more later after I become more familiar with its
potential...😎

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Daino, John is correct. The cranks are attached via std. square tapers
to the 180mm axle (spindle), which is otherwise a smooth and solid
stainless steel rod. The Phil Wood company kindly (but for a price)
made the longer-than-normal axle for me. The hub rotates faster than
the axle due to the gearing.
Pete

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I may have missed this, but how does one shift from one cog to the
other, or rather shift the driveshaft's connection from one cog to the
other?

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Stevyo, no shifting...think 1 wheel track bike. The jackshaft is a
solid piece that connects the 2 top cogs as one. Drive pressure goes
from the crank up to the jackshaft, then back down to the hub.

I rode it again briefly today, and it seems to magnify any input. You
step on the pedal and it accelerates. You backpressure the pedals and
it slows down, alot more than direct drive. I also notice that the
side-to-side effect of pedal pressure is pronounced, not too bad, but
maybe that's more to do with the 9" spread of the pedals. That's not
much more than a wide-hub direct drive, but there's definite Q-factor.
As I pedalled smoother it was minimized. And starts are a [censored], I'm
learning all over again!

Bottom line is that with less room for pilot error, I'm still working my
way up to go fast. I'm doing about 15 (only on the flats so far) with
much less pedal effort, but more balancing effort. 🙂

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If you ever make a production run of that monster, let me know. You've
got a sale!

JL

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unisk8r said:

*
Bottom line is that with less room for pilot error, I'm still working
my way up to go fast. I'm doing about 15 (only on the flats so far)
with much less pedal effort, but more balancing effort. 🙂 *

Open it up, you sissy. That's what protective gear is for. I know at
least ONE of the axle threads is done correctly. How much does the
assembled unicycle weigh? Have you determined a way around the
tensioning problem yet?

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unisk8r said:

it seems to magnify any input. You
step on the pedal and it accelerates. You backpressure the pedals and
it slows down, alot more than direct drive.

Isn't that unexpected? I would have thought that your input effects
would be reduced. If I ride on a bike in high gear, the effect
of more power on the pedals is slowly translated into more
speed.

Another question: can you swap the cogs relatively easily? It might
then be worthwhile to temporarily convert it do a geared DOWN 36",
effectively 24". People have talked about the virtues of such a
machine for MUni (great rolloverability but still low gearing) but
no-one has ever tried it. Or they didn't tell me.

Klaas Bil - Newsgroup Addict
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Klaas Bil said:

*

If I ride on a bike in high gear, the effect
of more power on the pedals is -slowly- translated into more
speed. *

That's just because you need more force to turn the wheel in a high
gear.

Gearing up in this way effectively has the same effect as putting an
even bigger wheel on it, except that the wheel is still only as heavy as
a 36" wheel, so you don't get as much of a flywheel effect as you would
on a 42" or whatever its equivalent to.

I think its probably the same feeling as when you put shorter cranks on
your unicycle, or, more like it, when you get on a bigger wheeld uni.

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unisk8r said:

*Stevyo, no shifting...think 1 wheel track bike. The jackshaft is a
solid piece that connects the 2 top cogs as one. Drive pressure goes
from the crank up to the jackshaft, then back down to the hub.*

Congratulations to an interesting design. I hope you will continue
telling us about how well it works on the road. But let me pose a
dummie's question: Why did you not go for a single chain design à la
giraffe? Would placing the cranks 15 cm above (or below) the hub's axle
make the uni behave much different? Or were there other reasons?

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