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Old 01-11-12, 02:53 AM   #1
realestvin7 
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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?



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Old 01-11-12, 03:18 AM   #2
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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!
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Old 01-11-12, 03:26 AM   #3
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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’.
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Old 01-11-12, 03:28 AM   #4
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Is it road, MTB, something else?
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Old 01-11-12, 04:39 AM   #5
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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:



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Old 01-11-12, 04:48 AM   #6
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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?
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Old 01-11-12, 04:58 AM   #7
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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...



Attached Images
File Type: jpg Motobecane_Durham_Crank_4.jpg (98.3 KB, 145 views)
File Type: jpg Motobecane_Durham_Crank_6.jpg (101.0 KB, 140 views)
File Type: jpg Motobecane_Durham_Crank_5.jpg (107.1 KB, 10 views)
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Old 01-11-12, 08:35 AM   #8
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Quote:
Originally Posted by randyjawa View Post
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.



Again, look at those huge teeth! Scary!

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Originally Posted by LesterOfPuppets
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!
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Old 01-11-12, 08:46 AM   #9
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Quote:
Originally Posted by pastorbobnlnh View Post
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.
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Old 01-11-12, 08:48 AM   #10
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Yes, there must have been a couple of chain jumping incidents during prototyping
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Old 01-11-12, 08:53 AM   #11
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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.
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Old 01-11-12, 10:51 AM   #12
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I want to WATCH somebody ride a bike with these on it. I don't want to try it myself. Lol.
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Trek 7000 MTB F/F -17" ST/55cm TT
Alpine MTB F/F - 23" ST/59cm TT
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Old 01-11-12, 11:32 AM   #13
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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.
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Old 01-11-12, 06:25 PM   #14
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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.
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Old 01-11-12, 06:31 PM   #15
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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.
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