Osymetric chainrings (mountians)

Discuss light weight issues concerning road bikes & parts.
tdudzik
Posts: 47
Joined: Sun Sep 02, 2012 2:17 am

by tdudzik

where did you get your time trial version of the rings? I've seen them on the internet once somewhere, but no where readily available.

DrGalactus
Posts: 96
Joined: Fri Jun 01, 2012 11:45 am
Location: Bristol, UK
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by DrGalactus

If you're lucky enough to be British ( :lol: ) they're available from http://www.cyclepowermeters.com/osymetr ... -148-c.asp

by Weenie


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Mario Jr.
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Joined: Sat Jun 12, 2004 8:49 am
Location: Denmark
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by Mario Jr.

grid256 wrote:I've put extensive miles on Qrings and tried endlessly to get Osymetrics set up on my TT bike but eventually gave up. The shifting was awful but the feel was great. Enter the new QXL rings. In my mind they're the best compromise of all the non round rings. They produce a feel similar to Osymetrics but shift smooth with zero problems especially with the new Red.


Yes, I'm sooo happy about the QXL rings, too! No problems with shifting as well on my SRAM Red.

natefontaine
Posts: 270
Joined: Wed Mar 31, 2010 3:37 am

by natefontaine

Contact Jonathan Carvner at OsymetricUSA.com that is where I got mine, might be a special order.

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jekyll man
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Location: Pack filler

by jekyll man

Official cafe stop tester

DrGalactus
Posts: 96
Joined: Fri Jun 01, 2012 11:45 am
Location: Bristol, UK
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by DrGalactus

:o they have the MTB rings in stock!

tdudzik
Posts: 47
Joined: Sun Sep 02, 2012 2:17 am

by tdudzik

I emailed the OsymetricUSA guys once, they said they were prototyping the TT rings now and that they would put them up in the store in the next month or so. This was like November or December.

JohanSten
Posts: 14
Joined: Sat Sep 20, 2014 12:24 pm

by JohanSten

Okay guys. I need some help here.

I´m thinking about buying a pair of O.Symetric chainrings to try out on my road bike, and TT this winter. The thing is that I ride as a Junior-rider. This means that I have "gear restrictions". Right now, the heaviest gear I can use is a 52t chainring combined with a 14t cassette. This gear is quite easy if you know what I mean (50 km/h++). As some of you said; the O.Symetric is "easier" than round chainrings. So, will this mean that I will "spinn out" my gears faster than the other riders?

Thanks.

Krackor
Posts: 257
Joined: Tue May 31, 2011 9:48 pm

by Krackor

Roll-out is just how far the bike goes with one full revolution of the crank. For a 52t chainring, that's 52 teeth-worth of chain whether it's an oval 52t or a round 52t or an osymetric 52t. If you can achieve a higher average cadence with the Osymetric due to the easy effective ratio in the dead spots, then you'll go faster on the Osymetric than on round rings.

You should probably ask your local officials about how they handle Osymetrics. You don't want to spend hundreds on new chainrings only to be disqualified by an unexpected clause in the rulebook (or by an uninformed official).

MRM
Posts: 309
Joined: Sun Jun 14, 2015 8:15 pm

by MRM

Taken from Bikeradar:

Stages engineer Andy Lull backed up Kerrison, and said that in his testing the non-round rings "do not seem to allow the rider to produce more power at the rear wheel through a mechanical advantage, but rather produce a higher power reading from crank-based power meters."

"I can’t speak to the biomechanical efficiencies or psychological advantages of non-round rings, only to the phenomenon of the fluctuating velocity biasing the crank-based power measurement," Lull said.


So do O.Symetric rings work at all, or is the 5-8% power increase the company claims down to pure measurement error?

TheKaiser
Posts: 439
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

MRM wrote:Taken from Bikeradar:

Stages engineer Andy Lull backed up Kerrison, and said that in his testing the non-round rings "do not seem to allow the rider to produce more power at the rear wheel through a mechanical advantage, but rather produce a higher power reading from crank-based power meters."

"I can’t speak to the biomechanical efficiencies or psychological advantages of non-round rings, only to the phenomenon of the fluctuating velocity biasing the crank-based power measurement," Lull said.


So do O.Symetric rings work at all, or is the 5-8% power increase the company claims down to pure measurement error?


They may "work" for some things, but there is a pretty well established effect of a phantom power increase (i have seen the figure 5-6%) vs. round rings. You can find a ton of info on this on the wattage based training forums, and I think there is some good info on it on the DCRainmaker blog too. In other words, if you are trying to prove that non-round rings work, you don't want to hang your hat on this particular power aspect.

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