This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.


Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Oval Rings
#1
I've just noticed the company who I purchased my spiderless chainring from are now doing oval rings....

So what difference is it actually going to make? Does anyone have any first hand experience? I've seen them on the TT bikes before etc....

I feel the appearance would annoy me....

<!-- m --><a class="postlink" href="http://absoluteblack.cc/sram-oval.html">http://absoluteblack.cc/sram-oval.html</a><!-- m -->

resim
Reply
#2
cf 1990's
Reply
#3
Supposed to effectively 'pull more chain' per pedal stroke than round rings. On paper it probably does make some kind of sense but I've never been sure that the flat spots (bottom of each pedal stroke) wouldn't simply be flatter to compensate. If it was possible to cheat geometry/physics out of free energy we'd probably be flying cloud cars to our floating palaces in the sky by now, but I've been wrong about this sort of thing before. They were called Biopace in the 90s and were quite short lived, possibly for good reason. I believe they were linked with knee problems but this may not have ever been proven. I don't know how well they'd play with your chain guide tho...
Reply
#4
Mmmm.. I had a Biopace chainset for years & can honestly say I knew not what that meant.
I also didn't notice the difference when it went.

My understanding is that the oval is deigned to even out power by giving you a "larger" ring when your legs are at the point of least power (top/bottom of stroke).  So the bulge is horizontal when the crank arms are vertical.

I've heard that people who are very good at peddling in circles get on very well with them (hence TT use I guess), but people who tend to just push down on the power stroke can find them odd, I heard things about knee issue too.

All subjective though as I had them & didn't even realise :B
Reply
#5
I tend to peddle in circles instead of stomping, something i consiously do instead of using pro peddle as i always forget to turn it off. They say you get the same speed as a 34 tooth but with the same effort as a 30, so seriously thinking of trying it with a 42 One-Up first gear when my current chainring wears out.
Reply
#6
Modern oval rings are different from Biopace. Biopace gave you more teeth in the dead spot and fewer in the power spot, with the rationale that by making the power portion easier, you'd have more energy for the weak part. That seem counter-intuitive to me. The new rings give you more teeth in the power part and fewer in the weaker portion. This makes more sense to me: push a bigger gear when you're strong and a smaller gear when you're weak.

Apparently the late great Sheldon Brown agrees with the Biopace way, though I haven't read his position.
Reply
#7
Here's the Absolute black ring <!-- m --><a class="postlink" href="http://vimeo.com/m/106824486">http://vimeo.com/m/106824486</a><!-- m -->

And Sheldon Brown on Biopace <!-- m --><a class="postlink" href="http://sheldonbrown.com/biopace.html">http://sheldonbrown.com/biopace.html</a><!-- m -->
Reply
#8
Very informative guys.
It seems the info I have "heard" is a bit muddled between the two, very different systems.
Reply
#9
Modern is opposite to bio pace so that there is less stress at the point where your knee is weakest. That's nice. My GF's road bike had old bio pace and, tho she couldn't feel it, it always seemed to me that the pedals were 'falling away' under my feet. Horrible things.
Keep it foolish...
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)