Patent number: 528145

http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

On Jan 13, 3:16 am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

In article
,
wrote:

On Jan 13, 3:16 am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

Interestingly enough, c) is not true!

http://sheldonbrown.org/gunnar/index.htm

I'd have to fuss to figure out if the chain length is precisely constant
for any position of the rings (and if Biopace vs. true ellipses
matters), but this is an effective demonstration that the chain length
change is negligible.

--
Ryan Cousineau http://www.wiredcola.com/
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing

On Jan 13, 1:03 pm, Ryan Cousineau wrote:
In article
,

wrote:
On Jan 13, 3:16 am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

Interestingly enough, c) is not true!

http://sheldonbrown.org/gunnar/index.htm

I'd have to fuss to figure out if the chain length is precisely constant
for any position of the rings (and if Biopace vs. true ellipses
matters), but this is an effective demonstration that the chain length
change is negligible.

--
Ryan Cousineau /
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing

It's hard to tell without any dimensions, but those chainrings looked
much more eccentric than Biopace. There's no way with a gearing other
than 1:1 for the chain length to stay constant for two elliptical
rings. I believe that the 2:1 arrangement can be lined up to avoid
the extremes though.

In article
,
wrote:

On Jan 13, 1:03 pm, Ryan Cousineau wrote:
In article
,

wrote:
On Jan 13, 3:16 am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

Interestingly enough, c) is not true!

http://sheldonbrown.org/gunnar/index.htm

I'd have to fuss to figure out if the chain length is precisely constant
for any position of the rings (and if Biopace vs. true ellipses
matters), but this is an effective demonstration that the chain length
change is negligible.

--
Ryan Cousineau /
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing

It's hard to tell without any dimensions, but those chainrings looked
much more eccentric than Biopace. There's no way with a gearing other
than 1:1 for the chain length to stay constant for two elliptical
rings. I believe that the 2:1 arrangement can be lined up to avoid
the extremes though.

I'm referring not to the design in the patent (which is clearly insane)
but to Sheldon's bike as a demonstration that you don't need a spring
loaded tensioner (or, I believe, notable amounts of chain slack) to run
a Biopace ring and a round cog.

--
Ryan Cousineau http://www.wiredcola.com/
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing

On Jan 13, 6:06 pm, wrote:
On Jan 13, 3:16 am, " wrote:

http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

Yes, that's what I thought. I've seen the egg shaped sprockets appear
and disappear over the years. The point of the patent seems to be in
having a chain for both pedals.

Here is a modern patent referencing this one.

"A drive mechanism applicable to bicycles for increasing the
efficiency of pedaling action via independent pedals with a
sinusoidally varying transmission ratio. The drive mechanism achieves
increased efficiency by making the pedals independently synchronized
with a varying transmission ratio"
http://www.google.com/patents?id=lUIZAAAAEBAJ

You know of any production bike using that?

On Jan 13, 1:05 pm, " wrote:
On Jan 13, 6:06 pm, wrote:

On Jan 13, 3:16 am, " wrote:

http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

Yes, that's what I thought. I've seen the egg shaped sprockets appear
and disappear over the years. The point of the patent seems to be in
having a chain for both pedals.

Here is a modern patent referencing this one.

"A drive mechanism applicable to bicycles for increasing the
efficiency of pedaling action via independent pedals with a
sinusoidally varying transmission ratio. The drive mechanism achieves
increased efficiency by making the pedals independently synchronized
with a varying transmission ratio"http://www.google.com/patents?id=lUIZAAAAEBAJ

You know of any production bike using that?

No, but that patent was filed by Rotor: http://www.rotorcranksusa.com/
They're not likely to be developing that particular design, but rather
filed the patent to keep some small part of it protected for
themselves.

" wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ
What happens here?

wrote:
As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.

" wrote:
Yes, that's what I thought. I've seen the egg shaped sprockets appear
and disappear over the years. The point of the patent seems to be in
having a chain for both pedals.
Here is a modern patent referencing this one.
"A drive mechanism applicable to bicycles for increasing the
efficiency of pedaling action via independent pedals with a
sinusoidally varying transmission ratio. The drive mechanism achieves
increased efficiency by making the pedals independently synchronized
with a varying transmission ratio"http://www.google.com/patents?id=lUIZAAAAEBAJ
You know of any production bike using that?

wrote:
No, but that patent was filed by Rotor: http://www.rotorcranksusa.com/
They're not likely to be developing that particular design, but rather
filed the patent to keep some small part of it protected for
themselves.

Locking up the 'belt with suspenders' dual chain market?
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On Jan 13, 1:16*am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

Dear G,

Regrettably, the rest of RBT prepares to suffer because you've shown
me the wonderful Google patent search.

Thanks,

Carl Fogel

Carl Fogel wrote:

Regrettably, the rest of RBT prepares to suffer because you've shown
me the wonderful Google patent search.

Somebody brew Carl a pot of strong coffee. I think he's going to be
busy for a while!

Chalo