Re: two-geared uni

Swiss manufacturer Schlumpf seems to have made a breaktrough in
developing their geared uni hub. According to the web site "mass
production" of their own two-geared unicycle will be launced in spring
2005.

http://www.schlumpf.ch/uni_engl.htm


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coughRcoughIcoughPcoughOcoughFcoughFcough


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What Obie here(I think) is trying to say is that weve seen this site in
a thread a while back...


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Catboy wrote:
> *What Obie here(I think) is trying to say is that weve seen this site
> in a thread a while back... *



Huh? I have a headcold. Nah actually I was not aware of a previous
thread. I was remarking that this is someone else's idea. If he has
contracted with this company, ignore this post.


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Catboy wrote:
> *What Obie here(I think) is trying to say is that weve seen this site
> in a thread a while back... *


Blimey! I'll do a closer check next time. But on the other hand, if I
keep posting this "news" I might be able to negotiate a discount from
Schlumpf.

BTW Obie, nice portrait of Jack Nicholson!


goldenchicken


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TheObieOne3226 wrote:
> *
>
>
> Huh? I have a headcold. Nah actually I was not aware of a previous
> thread. I was remarking that this is someone else's idea. If he has
> contracted with this company, ignore this post. *


I think given that planetary gear systems have been being made for tens
of years and Schlumpf have been making a very similar bottom bracket
based system for bikes, and are one of the few people who have the
tooling + ability to mass produce runs of something like this, we should
be pretty happy about this. As far as I can see, it's only similar in
that it uses a planetary gear system, the internals are presumably
somewhat different due to the different shifting systems involved. You
could as well say that Harper nicked the idea off schlumpf or Sturmey
Archer as say that Sclumpf ripped him off.

I think given the trouble harper was having trying to get a production
run of geared hubs made in Taiwan, it's great that one of the best
people producing high quality planetary gears for bikes is working on
it.

The only scary thing is what the price will be, the speed-drive for
bikes is something like £250. That's rather a lot for a hub (although I
guess some people did buy profile hubs for about that much when they
first came out).

Joe


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joemarshall wrote:
> *
>
> You could as well say that Harper nicked the idea off schlumpf or
> Sturmey Archer as say that Sclumpf ripped him off.
>
> I think given the trouble harper was having trying to get a production
> run of geared hubs made in Taiwan, it's great that one of the best
> people producing high quality planetary gears for bikes is working on
> it.
>
> *


I agree entirely. The planetary gear transmission has been around for
over 150 years. I even e-mailed back and forth with Schlumpf when I was
designing my system and trying to find a supplier of gears. I think
Frank Bonsch would agree also. There's very little that is original
about the idea and Schlumpf's shifting mechanism, should it work on a
unicycle, is a big engineering step forward.


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On Sun, 17 Oct 2004 13:19:52 -0500, "harper"

<harper@NoEmail.Message.Poster.at.Unicyclist.com> wrote:

>I agree entirely. The planetary gear transmission has been around for
>over 150 years. I even e-mailed back and forth with Schlumpf when I was
>designing my system and trying to find a supplier of gears. I think
>Frank Bonsch would agree also...

Yes, I do. About 5 years ago (after the ride across Minnesota) I have
talked with Florian Schlumpf about the idea of a geared up unicycle
hub. So the idea is not new.

I met him a few weeks ago at the Eurobike fair and his shiftable hub
is really good. Unfortunately the unicycle wasn´t ready for a test
ride. I convinced him of adding a 28" unicycle with optional brakes to
his range of products and I will surely buy one.

Frank - the 'other' gearhead ;-)

On Mon, 18 Oct 2004 07:27:44 GMT, (Frank Bonsch) wrote:

>I convinced him of adding a 28" unicycle with optional brakes to
>his range of products

Interesting development. Do you know if the frame will accommodate a
(big) Big Apple?

Klaas Bil - Newsgroup Addict
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On Tue, 19 Oct 2004 06:31:04 GMT,
klaasbil_remove_the_spamkiller_@xs4all.nl (Klaas Bil) wrote:

>On Mon, 18 Oct 2004 07:27:44 GMT, (Frank Bonsch) wrote:
>
>>I convinced him of adding a 28" unicycle with optional brakes to
>>his range of products
>
>Interesting development. Do you know if the frame will accommodate a
>(big) Big Apple?

Hi Klaas!

I don´t know. The 2.35" Big Apple is really fat. The 28" geometry
should be the same as the 20" which is shown on Schlumpf´s webpage. So
it could fit but it´ll be very narrow.

By the way: i tried a 2.35" Big Apple on my geared up uni and i didn´t
like it at all. I swiched back to a 1.75" Schwalbe Marathon after just
30km because it is much more maneuverable. But that may be my personal
opinion.

Frank

Frank Bonsch wrote:
> *By the way: i tried a 2.35" Big Apple on my geared up uni and i
> didn´t
> like it at all. I swiched back to a 1.75" Schwalbe Marathon after
> just
> 30km because it is much more maneuverable. But that may be my
> personal
> opinion. *

Hmmm, yeah, the heavy tyre combined with highish rotational velocity
(thanks to the gearing) will have a will of its own because of the
gyroscopic effect. Something to consider indeed. For my ungeared 700c,
however, I prefer a BA 2.35" much over the 35 mm tyre it was originally
supplied with.

Klaas Bil


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harper wrote:
> * Schlumpf's shifting mechanism, should it work on a unicycle, is a
> big engineering step forward. *
> -In the article linked to above -* - Shifting: direct shifting via
> push buttons on both ends of the spindle. No cables, no rods.
> *
when either of the two resident gearheads have a moment, could u explain
the difference to the rest of us in plain english?

the other aspect i couldn't help but notice is that fact that they're
also doing 1:1.5
are there a bunch of reasons why that is a 'popular' ratio for a geared
uni?


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The Schlumpf shifting has a little knob in the middle of the crank,
which you kick with your foot to shift. If it is possible to shift it on
the fly, it's a big step forwards from having to unbolt things from the
frame to shift.

As for the ratio, there's a limit to how high a gearing up you can get
from a single set of epicyclic gears (I think it may be 2:1) , as you
get closer to it, you have to use smaller and smaller and more delicate
gears for a given hub size, 1.5 is probably a good compromise. Also in
Schlumpf's case it's likely they're using the same gears in their
existing products, which do 1:1.5 gearing.

Joe


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joemarshall wrote:
> *...it's a big step forwards from having to unbolt things from the
> frame to shift.*
yeah, but can it open a 'root beer' (http://tinyurl.com/4p62d) ?





joemarshall wrote:
> *As for the ratio, there's a limit to how high a gearing up you can
> get from a single set of epicyclic gears*
kewl
that's the kind of technical info i thought might be behind it


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joemarshall wrote:
> *
> As for the ratio, there's a limit to how high a gearing up you can get
> from a single set of epicyclic gears (I think it may be 2:1) , as you
> get closer to it, you have to use smaller and smaller and more
> delicate gears for a given hub size, 1.5 is probably a good
> compromise. *


Joe is right, the limit without using compound gears is less than 2:1
which can't actually be attained. At the 2:1 ratio, the diameter of the
planet gears is zero and the sun gear and ring gear are the same size.

Since gears have teeth they can be thought of as having built in integer
limits, that is they are not continuously variable. In the geared up
mode, the number of teeth on the ring (outer) gear and the number of
teeth on the sun (inner) gear BOTH must be evenly divisible by the
number of planet (small) gears. If S is the number of teeth on the sun
gear, R is the number of teeth on the ring gear, P is the number of
teeth on the planet gear and N is the number of planet gears then the
gear ratio will be 1+(S/R):1 and S/N and R/N must both be integers and,
finally, R=S+2P. Any gear ratio design must meet all of these
constraints.


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