two-geared uni

[goldenchicken]

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

[TheObieOne3226]

coughRcoughIcoughPcoughOcoughFcoughFcough

[Catboy]

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

[TheObieOne3226]

Originally posted by Catboy
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.

[goldenchicken]

Originally posted by Catboy
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

[joemarshall]

Originally posted by TheObieOne3226



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

[harper]

Originally posted by joemarshall


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.

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
--
"I (...) made it without dying, which means mere mortals can do it. - John Foss"

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

[Klaas Bil]

Originally posted by Frank Bonsch
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

[GILD]

Originally posted by harper
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?

[joemarshall]

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

[GILD]

Originally posted by joemarshall
...it's a big step forwards from having to unbolt things from the frame to shift.

yeah, but can it open a root beer ?

Originally posted by joemarshall
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

[harper]

Originally posted by joemarshall

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.