Opinions on Oval Chainrings?

PB Forum :: All Mountain, Enduro & Cross-Country
Opinions on Oval Chainrings?
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FL
Posted: Sep 15, 2016 at 15:34 Quote
Are they a gimmick? Would the changing diameter affect the use of a chainguide? Curious to hear from people who have used them.

O+
Posted: Sep 15, 2016 at 18:07 Quote
I have been using an oval ring all year and it has made a difference. I have knee issues and used to get pain after rides, this no longer occurs. I feel like I climb better with it as well. If you are getting s new ring anyway, might as well give it a shot. There are for sure no downsides to it. I have an absolute black ring and it shows no signs of wear after close to a 1000 Km this year.

As for a chain guide. I know absolute black also makes one specifically for oval rings. It looks like if you set one high enough to clear the higher part of the ring, then it may work fine. Not actually sure though. If you have a guide that goes fully around the chain, not just above the ring and chain, then it likely won't work.

FL
Posted: Sep 15, 2016 at 20:23 Quote
Hm. Sounds like something I would like to try but it seems like it may not work with my chainguide. I've got an upper guide with a lower pulley

Posted: Sep 17, 2016 at 14:03 Quote
I'm not as sold on after trying one. They're OK. I have knee issues and think I just prefer to ride in a lower gear. They bend easier too

Posted: Sep 17, 2016 at 15:16 Quote
How do they behave with a clutched derailleur? Does the chain length changing with every stroke create drag?

Posted: Sep 17, 2016 at 15:28 Quote
JonProce wrote:
How do they behave with a clutched derailleur? Does the chain length changing with every stroke create drag?

Haven't had any issue with increased chain growth on mine. Got an one up components oval ring and xt 10 speed clutch derailleur on a 160mm travel bike.

O+
Posted: Sep 17, 2016 at 19:45 Quote
There is no chain growth at all with them. You are able to run them on a single speed if you like.

Posted: Sep 17, 2016 at 21:21 Quote
ShantySpark wrote:
There is no chain growth at all with them. You are able to run them on a single speed if you like.
There is a tiny amount of chain growth and you wouldnt be able to run them on a single speed with out a chain tensioner.

I run one. I think there is a small improvement...its definitely not a huge difference or anything.

FL
Posted: Sep 18, 2016 at 7:22 Quote
invrted180 is right. A bike came into my shop one day that was set up SS with an oval ring and because of the changing diameter of the ring, a chain tensioner was required otherwise it would be too loose when the chainring was in the "flat" section of the pedal stroke.

And I think for my situation, where I wanted to put one on my bike with a top and bottom chainguide, it would work, it would just wear out the clutch mechanism in my derailleur way faster than normal because the derailleur would have to compensate for that chain growth with every single pedal stroke.

It sounds like it doesn't even make a huge difference though so I'll happily pedal up climbs on my round ring!

Posted: Sep 18, 2016 at 7:59 Quote
Oval rings work better for some than others... largely personal preference. But there are some things to consider...

The major (reported) benefit of an oval ring, is to place the tallest part of the gear in the part of your pedal stroke that has the most power... Most MTB oval rings are not adjustable, as individuals vary (body/bike/riding style) a non adjustable oval ring won't work the same for everyone. There are road rings on the market that are adjustable, as in you can rotate them to find the sweet spot, but this takes some trial and error.

several road teams say, that after a pile of research they are unable to show an improvement in power or efficiency. Some big name roadies have dropped the oval... this argument is countered (by oval ring manufactures) to say that amature slobs like us, will benefit from it more than a top level roadie.

Many riders actually gear down when the transition to an oval ring (32 oval is easier than a 32t round, It has a gear ratio closer to 31t). so the perception that things got easier is related to running a lower gear, not necessarily the shape of the ring.

I run an oval on my hardtail right now, and it works great, I can't tell the ring is oval... but I put the same ring on my all mountain bike and I felt knee discomfort and that my cadence was awkward... I suspect that this is because of varied geo between the bikes.

O+
Posted: Sep 18, 2016 at 17:52 Quote
rode my oval for the first time today. felt the same. oh well.

Posted: Sep 18, 2016 at 18:11 Quote
arnie86 wrote:
rode my oval for the first time today. felt the same. oh well.

Its supposed to feel the same... yours is working.

and yet some how its supposed to magically generate more watts...

O+
Posted: Sep 18, 2016 at 18:18 Quote
mistermtb wrote:
invrted180 is right. A bike came into my shop one day that was set up SS with an oval ring and because of the changing diameter of the ring, a chain tensioner was required otherwise it would be too loose when the chainring was in the "flat" section of the pedal stroke.!

not sure about that. surely the chain wrap on the chainring at all time is just half the circumference of the chainring itself, regardless of orientation. the difference would be the vertical chainline depending on what part of the oval you are on. tension should remain mostly the same.

cmcrawfo wrote:
and yet some how its supposed to magically generate more watts...

that felt the same too lol probably just me being a weakling in general. cant say I really noticed much of anything, but it works so it'll stay on until it dies.

Posted: Sep 18, 2016 at 18:27 Quote
arnie86 wrote:
mistermtb wrote:
invrted180 is right. A bike came into my shop one day that was set up SS with an oval ring and because of the changing diameter of the ring, a chain tensioner was required otherwise it would be too loose when the chainring was in the "flat" section of the pedal stroke.!

not sure about that. surely the chain wrap on the chainring at all time is just half the circumference of the chainring itself, regardless of orientation. the difference would be the vertical chainline depending on what part of the oval you are on. tension should remain mostly the same.

cmcrawfo wrote:
and yet some how its supposed to magically generate more watts...

that felt the same too lol probably just me being a weakling in general.
Hmm...maybe I'm wrong. Although you can see the derailleur oscillate a tiny bit maybe its not enough to mess with a single speed.

Posted: Sep 18, 2016 at 18:29 Quote
I would advise a tensioner on an oval ring SS setup. Otherwise you won't be able to properly tension the chain. Not that it wont work...

Here is a video of one without a chain tensioner.. while the guy seems to think it's ok, its clearly too tight.



then again, I guess we could ask why bother getting proper chain tension in the first place ... ultimately, it just prevents premature wear (chain and BB)... and if you are not monitoring the chain for wear, it would eventually fall off.

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