# Unusual elliptical chain ring



## dnc1 (Sep 22, 2019)

A friend recently found this, any ideas anyone?
This first photo shows it in 'as found' condition.....





It's marked 'ELAN', in a typeface that screams French to me.....












The adaptor plate allows it to fit on these 'Williams' cranks.....








Thanks in advance for any help/info.
Darren.


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## Jesse McCauley (Sep 22, 2019)

The two different ages of metal scream composite object to me. That is my 1c, not enough insight for 2.


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## dnc1 (Sep 22, 2019)

Thanks @Jesse McCauley.
It's definitely much earlier than the Williams  chainset,  that adaptor was obviously made up later to allow it to fit on a British machine at some time.
Perhaps because the original French chainset would have had a different axle diameter and wouldn't fit on a British bicycle. 
My friend found the William's cranks that match the adapter plate yesterday.


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## juvela (Sep 22, 2019)

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This ELAN elliptical calls home a Terrot Super Course of 1936.





















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## dnc1 (Sep 22, 2019)

Thanks @juvela,  I thought 20s/30s French origin but couldn't find an image.
My friend will have to look for some Terrot cranks now.
Stirling work sir!


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## dnc1 (Sep 22, 2019)

From the last two photos,  it suggests to me that you can position the apex of the ellipse in several positions in relation to the driving crank arm?
Curious!


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## juvela (Sep 22, 2019)

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Here is one on a Cycles Delly machine of slightly later.

Delly badge property of Schmidely.


















Delly & Terrot were both located in Dijon.

Perhaps maker of "ELAN" c/w's domiciled in same area...

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## juvela (Sep 22, 2019)

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c/w's appear to be made to mount to a standard 116mm BCD three-arm chainset

wondered as to meaning of marking "FR8ET"

evidently the ELAN folk did no ha' an ampersand in their stamping die set so they employed a small numeral eight in its place...

finally dawned on me dull "braine" that the whole marking should read "Brevete FR & ET" ... translation: "patents France and Foreign"

(not the sharpest tack in this or any other box)


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## juvela (Sep 22, 2019)

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Closeup views of cleaned set remounted to Terrot -









View of cleaned drive complete -




[the little j-shaped thingy above the chainset is an oiler(!)]

Chainwheel mounting and usage instructions from "ELAN" :


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## troy boy (Sep 22, 2019)

Juvela ,dull braine? you are like a walking encyclopedia your lightweight knowledge is incredible many thanks for your contributions. Brian


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## blackhawknj (Sep 22, 2019)

Interesting. There was some interest in elliptical/out of round chain rings in the early 1980s, I recall one woman member of my club said they helped to eliminate knee discomfort. IIRC people found out they could not be used with a derailleur and their benefits were "greatly exaggerated".


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## dnc1 (Sep 22, 2019)

troy boy said:


> Juvela ,dull braine? you are like a walking encyclopedia your lightweight knowledge is incredible many thanks for your contributions. Brian



Ditto, cheers @juvela !


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## 1951 C.W.S (Sep 24, 2019)

what would be the use of something like this?


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## bikejunk (Sep 24, 2019)

My 1893 Columbia had an elliptical sprocket  and yes back in my racing days in the 1980s we had Bio-pace elliptical sprockets . 1951 C.W.S they supposedly give you a mechanical lever action advantage over a round chain ring - I found the messed up my perfect circles in a sprint


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## juvela (Sep 25, 2019)

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Here upon the puddle's occidental margin we have had some aftermarket non-round chainwheels offered from time to time.

One recalled from the mid to late seventies era was the Durham.  For several years there each time an enthusiast opened a cycling periodical there would be a mailorder advert from Durham.

Theirs were done in dural.  One problem for these cottage industry operations was the decision as to what drillings to offer.  Since they were done on a small scale more than one drilling option would shoot up the overhead...

Here are two models of Durham's from BITD -

for three-arm 116mm BCD:


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		https://flic.kr/p/izaUfd


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		https://flic.kr/p/iy6rrX

for five-arm 144mm BCD chainsets:






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## dnc1 (Sep 25, 2019)

My friend is in the process of fitting it to a bare steel '30s Hercules sports bike, I'll post pictures when I have them.
I came across a few of those 'Durham' chainrings @juvela, whilst searching for info on the Elan example.  
Interesting that this idea keeps recurring  through the ages. As @bikejunk implies above, a probably very sound idea on paper that proves less so in actual use,
By the way @bikejunk, do you have any photos of the version in your 1893 Columbia?
I'd like to see that.


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## Cowboy in NC (Sep 25, 2019)

I had a similar skip tooth sprocket years ago---sold it on Ebay. Someone here on the Cabe bought it- because they posted a picture of it . It was called a "Rock-o-Matic Rocket Sprocket, circa the 1940s. " Maybe they will see this and repost or maybe someone will look it up.
God Bless,---Cowboy


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## New Mexico Brant (Sep 25, 2019)

I believe this to be a 19th century Columbia version:


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## dnc1 (Sep 25, 2019)

Wow @New Mexico Brant , that almost looks homemade.  I wonder how it feels in use?
Very cool!


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## juvela (Sep 25, 2019)

New Mexico Brant said:


> I believe this to be a 19th century Columbia version:
> 
> View attachment 1069336





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Wow indeed!

Shape looks a dead ringer for the Bernard Hinault:









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## New Mexico Brant (Sep 25, 2019)

This is from a Feb. 1898 _The Wheel :_

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## juvela (Sep 25, 2019)

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The Durham product takes it name from founder of the enterprise Roger Durham.

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Darren -

You have done an outstanding job with the description and images of your friend's item but have not told us if it's dentition is intended for 1/8" or for 3/32" _chaine_.

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## New Mexico Brant (Sep 25, 2019)

Why not try a square?


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## Kickstand3 (Sep 25, 2019)

New Mexico Brant said:


> Why not try a square?
> 
> View attachment 1069480




Wild !


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## 49autocycledeluxe (Sep 25, 2019)

I'm thinking if that were a good idea we would be doing it today. I gave myself a headache trying to figure the physics of it all and what it would actually do.. I'm going to go lie down.


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## juvela (Sep 26, 2019)

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Then there is the wheelbuilder's chainwheel...





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## Cowboy in NC (Sep 26, 2019)

Found a picture finally   late 40s- made in Miami, Fla. ---Cowboy ------Notice is Skiptooth...


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## dnc1 (Sep 26, 2019)

Nice to see so much interesting info on this subject! Cheers people!


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## Andrew Gorman (Sep 26, 2019)

I have one similar to the Durham, but with a double chainring. Since I don't even like Biopace rings I haven't put it on a bike.  I have thought about turning it into a clock.


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## dnc1 (Sep 26, 2019)

Very nice @Andrew Gorman, please don't turn it into a clock!
What age do you think yours is?
I'm seeing 52 teeth on there, do you measure these things as you would  a conventional chainring?
What cranks would it fit?
Here's a vintage twin ring example....


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## Andrew Gorman (Sep 26, 2019)

It came off of a heavy 10 speed frame I found in a junkyard 30 years ago, with TA aluminum cranks attached, so probably 1960s to 1970s.


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## juvela (Sep 26, 2019)

Andrew Gorman said:


> I have one similar to the Durham, but with a double chainring. Since I don't even like Biopace rings I haven't put it on a bike.  I have thought about turning it into a clock.
> View attachment 1069693




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Thanks very much!

Looks to be the 50.4mm BCD.

Interesting that the maker provides the user with the option of two different mounting positions.

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## Andrew Gorman (Sep 26, 2019)

I noticed that too.  One seems to be marked "15" with a numeral one as an arrow, and the other "CR".  I have no idea what that means.


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## juvela (Sep 26, 2019)

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These two-plateau models make me jaw drop.

Can no imagine watching a front mech attempting to do its job...  :eek:

A bit like asking Bambi to herd Godzilla.

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## Andrew Gorman (Sep 26, 2019)

I think you would have to very careful when you made the change!  Mine has a LOT more wear marks on the big ring than the smaller, 36 tooth ring.


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## skiptooth (Sep 26, 2019)

That is so cool !!  looks like a football  id like to pull the trailer with that


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## Jesse McCauley (Sep 26, 2019)

Anyone have a pic of Mel Shorts bike with the Triangular ring?
Hannah Simpson has one as well, killer bikes with the offset from center rear cog to compensate. Crazee stuff 


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## juvela (Sep 27, 2019)

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Found this image of a Durham two-plateau arrangement with a drilling for the 86mm BCD.

Look at the wylde adaptation for a front mech!  






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## razinhellcustomz (Sep 28, 2019)

New Mexico Brant said:


> I believe this to be a 19th century Columbia version:
> 
> View attachment 1069336



Highly Unusual!! Razin.


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## juvela (Sep 28, 2019)

Cowboy in NC said:


> Found a picture finally   late 40s- made in Miami, Fla. ---Cowboy ------Notice is Skiptooth...View attachment 1069672


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## juvela (Sep 28, 2019)

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Found this additional example of a Durham fitted to a three-arm 116mm BCD spider.

It even still has it paper label.  No wonder so few of the labels have survived!






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## dnc1 (Oct 6, 2019)

Here is my friends Hercules with the chain ring installed.....








He describes it as "like being on a cross trainer at the gym" in use. A bit bouncy and quite weird!


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## juvela (Oct 6, 2019)

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Thanks for posting!

When I saw the small edition of the first image me thought was "wonder just how long that rear mech is going to last!" ... then saw in second image that is is not a mech but a tensioner.   Sensible arrangement.  


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## dnc1 (Oct 13, 2019)

I finally saw Adam's Hercules in the flesh at the Benson VCC annual social evening last night. 













He kindly allowed me to take it for a quick spin around the car park at the venue.
It's an interesting riding sensation.  It feels like there is a very, very small moment where you lose power; I can only liken it to the feeling of a hub gear slipping or, a loose crank/cotter pin as you push down on the power stroke.
He tells me it does seem to make going up hills slightly easier.
Will see how it fares when he's next able to come on one of our 25 mile rides.


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## juvela (Oct 31, 2019)

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Thanks very much for this report and the additional images.  The mighty Herc's frame appears to be in bare metal; does Adam have a coating on there to protect it from corrosion?

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Minor addendum on the Durham elliptical chainwheel -

Creator Roger Durham is also the person behind the Bullseye line of cycle products:





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## 100bikes (Oct 31, 2019)

I've told people over the years  that I have been in the industry long enough for  5 iterations of oval rings.
Dates me for sure!!!!


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## 100bikes (Oct 31, 2019)

My Durnam ring story includes the recent passing of Chuck Mc Monagle in Green Bay. 
He was a fred(like me) , but a nice guy.


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## dnc1 (Feb 10, 2021)

I have acquired the 'Elan' chainring and cranks from my friend Adam.
Looking forward to finding some appropriate French period cranks and fitting it on my "new" Ciclos Minaco project.


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## all riders (Feb 23, 2021)

Indeed a predecessor to the rather common Shimano Biopace of the 80s-only several shown here have a much more radical ellipse. The Shimano version is not immediately obvious to the eye or legs. As to the purpose, they are supposed to make it easier to turn when your legs are at the point of the circle where they can contribute the least force, as the available power of the legs builds so does the diameter of the ring--then the ends of ellipse engage during the power stroke. If you measure the distance between the points of the football, that's the effective diameter of the chainring--but should require the same energy as one several sizes smaller (if round).  BTW mount your crank arms in the wrong relation to the ellipse and you're screwed.
  I've never thought about it 'til now, but I wonder if it was named Biopace because it used the Golden Ratio -1.618 (or close to it). Anyone know?


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## dnc1 (Feb 24, 2021)

It was used apparently in 'Le Tour'.....




I'll be trying it out with a period BSA flip-flop hub (fixed/free).
I'm in the process of modifying a very early Cyclo 2-speed derailleur to use in place of the missing "Galet".


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## juvela (Feb 24, 2021)

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@dnc1 -

since you will be mounting one...

as i look at machines fitted with simple ovals (as opposed to something more complex such as Biopace)  cannot help but wonder if there are any differing schools of thought as to the most efficient position to mount it in relation to the crank arm

did you happen to discuss this with the strongman's pilot perchance?

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## dnc1 (Feb 25, 2021)

Adam only had it in the one position when fitted on his Hercules. 
I'll try it in various positions of course, I think you'd have to.
I think others have mentioned elsewhere in this thread that it doesn't work as well in the other crank orientations.


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