Classic & Vintage - Vintage OVAL chainring ... What can you guys tell me about it?

Couldn't pass this NOS oddity up. It features 54 teeth and a 144 BCD. What would have been its intended purpose? And in which position would it mount?

http://i246.photobucket.com/albums/gg93/realestvin7/Bikes/Bike%20Parts/For_Sale2297-1.jpg

http://i246.photobucket.com/albums/gg93/realestvin7/Bikes/Bike%20Parts/For_Sale2298-1.jpg

Yours was made by Roger Durham in the 70's. Roger is the guy we have to thank for Bullseye cranks. He is an old friend of mine, living in Scottsdale az. Awesome find!

Uh? That’s way past crazy. I’ve never understood the ovalized chain ring era thing. Nerdy engineers seeking their PHDs were obviously involved. ‘Damn you PHD seeking smart people’.

Is it road, MTB, something else?

That ring has to have the longest, meanest, most intimidating looking teeth of any chainring I've ever laid eyes on! A competitor looking at it, would probably flinch, miss a shift, and immediately fall back!

I have seen one (in a picture) once before, and IIRC, when the crank arms were horizontal or East-West on a compass, the ring was pointing North-South.

Found these pictures online:

http://t3.gstatic.com/images?q=tbn:ANd9GcQp_yO0L_aldQ1u4lIxZlsd4RJ9BANZvVVh666lmqHsGKaFB_4BDkkcJ58_

http://t3.gstatic.com/images?q=tbn:ANd9GcQH1R-XIZC0JNplW9vJbhkdXCcqR3r3RT17fGBMDktEhySweo2tcg

Wonder what the two extra holes are for. Bold holes for some kinda ramps? Pins to keep the chain from wedging in between ring and crank arm?

I have one of those chain rings on a Motobecane Mirage. What a POS! I rode the bike once or twice and the feel was horrible. The bike felt like it was bouncing as soon as my rpms started going up...

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I have one of those chain rings on a Motobecane Mirage. What a POS! I rode the bike once or twice and the feel was horrible. The bike felt like it was bouncing as soon as my rpms started going up...


Now that I see Randy's post again, I'm pretty certain this is where I remember the picture from.

http://www.bikeforums.net/attachment.php?attachmentid=233185&d=1283956701

Again, look at those huge teeth! Scary!


Wonder what the two extra holes are for. Bold holes for some kinda ramps? Pins to keep the chain from wedging in between ring and crank arm?

Mounting holes for an emergency cut off release!

That ring has to have the longest, meanest, most intimidating looking teeth of any chainring I've ever laid eyes on! A competitor looking at it, would probably flinch, miss a shift, and immediately fall back!

I think that was intended to prevent derailment.

Yes, there must have been a couple of chain jumping incidents during prototyping :)

I remember when these things showed up in the seventies and then when Shimano tried to force them down our throats in the late eighties or early nineties. I'm pretty sure they made an appearance in the thirties or sometime around then. Anybody know the history of oval chainrings? I'm always fascinated by ideas like this that keep being brought back from the dead just when everybody has forgotten about them.

I want to WATCH somebody ride a bike with these on it. I don't want to try it myself. Lol.

I remember those from the 70s. Seems like an idea that rears its head every 15-20 years through the course of bicycling history. Never used one, but I hated BioPace.

I think it's for people who ride around at 40 RPM.

I would love to add it to my collection. I have most of rogers stuff except the chainring.

I think it's for people who ride around at 40 RPM.

Though I did not try to estimate my rpm, I am pretty sure I was lower than that. Honestly - the feel is unmistakable and scary. None the less, I have had the bloody bike for about ten years and still resist the urge to do something with it. Perhaps I should make a video of the mechanism in action.