non-round chainrings?

[ultrazenith]

I see non-round chainrings are back in fashion, with no science to back them up. Opposite to Biopace, these new rings give you a harder gear at the strongest part of your pedal stroke. The hype from the manufacturers and the magazines sounds good, but no studies have found conclusive evidence that using these rings does anything other than make pedaling feel a little bit smoother. Logically, round chainrings are unlikely to be the most efficient shape, but the challenge seems to be finding a better shape and then doing the scientific testing to see if it makes things better (faster, etc.?).

Which brings me back to the much maligned Biopace. People often say Biopace was wrong, but nobody ever says why, apart from the stories about bad knees. Sheldon Brown made a good argument that Biopace evens out the rate of power transmission to the rear wheel, which in turn *might* improve traction for off road riding. Has anyone experienced this effect?

The modern oval rings ought to make even larger the difference in power between the strongest part of the pedal stroke and the dead spot. If, as Leong et al. conclude, using a modern oval ring gives basically no improvement in performance (http://trstriathlon.com/elliptical-chai ... -let-them/), then *maybe* we'd be better off going with Biopace purely for the *assumed* improved traction? This might be bollocks, but how funny would it be if al the hype and testing of modern non-round chainrings led us back to biopace being faster?

 

[Stick Legs]

I kind of want Biopace on one bike just to have it. if that makes sense.

 

[Woz]

Re:

I was surprised team Sky (aka Brailsford measure everything to death) had riders using both types of rings.

Seems personal riding style is a factor in the success of non-round rings?????

 

[Stick Legs]

I'd say that the supposed benefits are out weighed by the likely hood of an unshipped chain.

Like David Millar's weight saving no front mech idea!

 

[jimo746]

Re:

I couldn't tell any difference between Biopace and regular round rings tbh!
I think Wiggins did use them (modern oval rings), then decided not to, Froome still uses them as far as I know, I believe it's down to rider choice when it comes to the chainrings they use. I did read a good article on the subject a few weeks ago but I can't remember where :?
I use one of the Absolute Black oval chainrings on my 1x10 full-sus bike, I think at first I could sense a slight difference,but after a few rides it just feels normal, the article I read put a lot of it down to a placebo effect and "percieved" differences, when in fact there was no measurable difference.
I know with the Rotor chainrings you can adjust where the high/low point of the oval sits and fine tune it for your riding style etc, one of the criticisms of the original Biopace was that it was the right shape ring but just in the wrong orientation, which could make sense but then I'm not sure I believe that the "Big S" would make a faux pas on that scale...

 

[Stick Legs]

I think if they looked cool a lot more people would perceive the benefit.
See deep section carbon road rims.

 

[hamster]

The idea is that they give a reduced diameter over the top dead centre so that you get a reduced load when you can apply least force. Biopace actually did the opposite, the idea was that it created an action more like running and that at TDC there was a significant backwards force from the lower pedal (think pushing with your foot).

Speaking personally, I hated the noticeable pulsing torque and joyfully confined the rings to the bin in 1991. If they work for you, great.

 

[themountie]

I have some old bio strong no round rings

 

[mattr]

I'm trying some at the moment, as i got them for less than half price, cheaper than the round rings i wanted.

TBH at lower RPM/higher torque (sort of 75-85 rpm ish) i find them to feel better than round, unfortunately, i generally ride at a much higher cadence than that (i rarely drop below 90) then they feel a little odd. I'll be experimenting with the clocking of the rings in the spring, only done 25-30 hours on them so far. Will get some actual info in the spring too, rather than just riding around.

Pity Leong didn't actually use some pros rather than mid pack amateur race fodder. Cat 3 and 4 in the study, hardly representative of the sort of person who needs to chase a 0.5% advantage. Less pies and more training would help far more than shiny chainrings. And more time on them. As far as i can tell from the study they had virtually no time at all to get used to the changes they'd need to make in pedaling style.

 

[mattr]

And FWIW, i tried biopace when they were originally out, swapped to some round rings pretty sharpish, the way the pedal seemed to fall away was disconcerting to say the least!