[Closed] Oval Vs round chainrings

Having tried one when they were fashionable (and cheaper than a DM round one) a few years ago, 5 minutes after putting it on & couldn't tell any difference. It wore out, and round ones were cheaper, so I put a round one on.

Can't tell the difference.

I found the most noticeable difference was when climbing steep tarmac, there was no (or certainly much less) pedalling in squares.

Currently got oval chainrings on the hardtail and fat bike and round chainring on the FS.

I'd say there's a benefit to an oval ring on the SS. Been riding the same SS 29er bike on the same local trails for 8 years and between the 2 I prefer the oval ring. On a geared bike I'm not convinced, I tend to use gears to help get on top of the gear so any difference in power application during the crank rev that an oval offers seems minimised or maybe neutralised.

I can't tell any difference usually but of course that doesn't mean there is no difference. But on the fatbike, it's really obvious that when pedalling in a low gear while seated (ie grinding up a road) it's bouncier with round than with oval. And that bounce is all wasted power basically where I'm going up and down instead of forwards.

I've gone back to round on the big bike just because it was cheaper and it made for better fitment with my chain device. But the fatty is staying oval.

I'm currently converting all my bikes to oval, definitely felt they helped me when spinning a higher cadence, everything just felt smoother and 'nicer'.

Had been running oval inner, round outer, but switched to oval/oval on the summer bike, and once again felt spinning in the bigger ring was smoother and nicer with the big oval.

I'm combining this with a knee-saving regime of generally higher cadences/lower gears, so one might be confusing the other. I do believe the benefits of the oval ring relate to the slightly lower gear at the flat part of the oval co-inciding with when the knee is at its weakest, helping reduce force through the joint. Handy if you're already nursing abused cartilage.

Don't pretend any of the above observations are very scientific, and don't believe there's any really performance benefits except fewer sore knees!

I've run them for 9 years on the road bike, but only just put them on the mtb. I found I had less muscle soreness after really long road rides, so stuck with them. Recently tried the pedalling analysis software from Rotor and found my pedal stroke is pretty smooth (you're supposed to get as close to a perfect circle as possible).

I like the feel on SS, I don't believe there's any power benefit tho (else it's be easily prices and everyone would have them).

I imagine a lot of the benefit is dependant on pedaling style. I suspect a lot on here have a reasonably smooth, spinning style. I put one on my bike and couldn't really tell, but my mate who's a bit of a left, right, up, down masher tried it and found it a huge improvement.

https://singletrackmag.com/forum/topic/oval-chainrings-5/

when you first try them it is difficult to discern a difference, and many riders take this as evidence that they are pointless/snakeoil, etc. However, if you ride with them for a while (say a week/150 miles) your pedalling technique adapts and indeed the way your muscles produce power, so when you go back to a round ring the difference is noticeable.

I'm on ovals on everything now and when I ride any of my mates' bikes with round rings they feel rubbish. It's more obvious on road/rigid bikes than FS though.

I think they help going up steep hills, where the slow-down between pedal strokes is at its most marked. Also, on really steep hills when you are already in first gear* but could do with an easier one so are having to mash it a bit. It helps get the pedal over the top, which is the most difficult bit.

* So particularly with 1x systems where, if you are old and weak of leg like me but ride places where the hills are steep, also like me, your easiest gear is likely to be a bit of a compromise, with 10 speed anyhow.

I bought a fat bike that had one on. I rode it a couple of times and couldn't tell any difference.

I swapped it for a smaller round one because I'm unfit.

I mainly use ovals as they remove almost all of the knee pain I used to get from my right knee.

For that reason alone I'm a convert.

I've got a couple of old road bikes with biopace chainrings on them. I always felt they were easy to ride but I assumed it was the ridiculously skinny wheels and tyres and lugged frames with skinny steel tubes. Never occurred to me it might be the chainrings. Always thought it was a bit voodoo-ish.

Maybe I'll start scouring eBay for more. See if I can find some with a bcd so I can use them on my newer bikes

Although I think the biopace were oval on the other "side" to the modern ones.

It makes sense for chainrings not to be round. That isn’t how your legs work, they don’t produce consistent power for the whole power stroke as your leg is a lever so makes sense to match gearing to the way your legs provide the power. I like them and they don’t do any harm so may as well have them than not. The hearing is the same so no wonder people don’t feel any real difference but the main difference is in the smoothness of how the power comes on and off. I think you notice it over time. It’s more of a tweak or slight improvement than a step change. Definitely produce a better pedalling stroke. The ones you buy off the shelf are not that high in their ovality and are just genetically oval. If you were doing it properly you’d get bespoke ones for you made up. Froomes rings look very different to the off the shelf rings, so your bound to get more benefit in that case. It they’re very speedy so the generic ‘slightly oval’ ones will do for most of us.

I had a Works Components 32t oval ring set up with XT 1x11 11-42 on my old Specialized Camber which I sold two years ago.

From memory I found it easier to climb steep and long seated fireroad climbs on the lowest gear on that bike (42t) compared to my current bike (32t regular round front ring, 46t XT rear).

The difference isn't dramatic and certainly not enough to justify ditching a perfectly good chainring however once my current ring wears out I'll definitely replace with another oval ring and see if it really did make a difference.

Apparently oval rings can cause premature wear to the clutch on Shimano rear mechs though.

Oval rings made me hate my single pivot Marin. Made it feel like a bobbing undamped bike.

Round ring back on and it feels good again.

biopace is the opposite to modern ovals. Biopace was a silly idea that died.

most ovals are around 10% ovality. Rotor go to 12.5% with the CX1 and 16% with the QXL.

Gasket, this was last week with a modern ring.

Mini hijack ... Will an oval ring keep the chain tension consistent on an SS with an eccentric BB?

Moe

Subscriber
Mini hijack … Will an oval ring keep the chain tension consistent on an SS with an eccentric BB?

I liked into this when considering going ss.

The consensus is all is fine ss but you do need to leave the chain a little slacker than usual.

biopace is the opposite to modern ovals. Biopace was a silly idea that died.

That's what I thought. It has (had) it's fans though. Oval Elliptical chain rings are nothing new. They come and go. Doubtless in a couple if years people will be saying the same thing about today's ovals. Couple of years after that they'll be back in fashion though.
You could orient biopace rings to the modern style by rotating them on the spiders

I happily swap between Q rings and round rings without really noticing a difference. I do most of the bigger rides on Q rings now so can't comment on fatigue or recovery. The only time I can sense a difference is when spinning a small gear, it's sometimes a bit awkward for me.

The theory makes sense and they dont make things worse.thats all I can say for sure. Havent noticed a difference but that doesn't mean there isn't one. I'm not very tuned in to subtle changes.

I have a mix of round and oval chainrings.

I do notice it feels very different when switching between them.

I find the oval rings lend towards a more stomping pedaling style with less ankle movement, and spin more easily at a higher cadence. Thus I think they can help for out of the saddle and near to above threshold work where rider is probably not going to be able to sustain good pedal technique. This si typical for MTB where there tend to be loads of short efforts way above threshold.

I remember using biopace BITD and really didn’t like them and have long since regarded ovals as reissued biopace so haven’t looked any further into them.

Until the comment above that says modern ovals are nothing like the biopace of old. How so please?

Perhaps the suitability of oval chainrings also depends on an individuals pedalling action? A smoother action possibly gaining less perceived benefit than a more stompy action?

https://en.wikipedia.org/wiki/Biopace

So they are opposite effects (thouigh at 90 degreees to each other).

Thanks for the link @greyspoke. I still feel,I need a side by side picture of the two to see where the difference is in ovality, as it were.

In a sense biopace achieves the opposite of modern oval rings.

Biopace aims to reduce leverage during the power phase of the pedal stroke to smooth out the forces on the legs and reduce peak stress in the knees.

Modern oval rings aim to reduce leverage during the dead phase of the pedal stroke to speed rotation of the cranks back to the next power phase.

I love oval. I will never go back to round. The feel is smooth. Nothing like biopace back in my timetrail days

I'm about to pick up a retro bike (well, old) with biopace.

Not entirely looking forward to riding it!

I have an old Marin with biopace and really like it.
well done for getting a retrobike.

Jedi, which ring do you run and why did you choose that brand?

Ta, it's the exact bike I had in 1988, my 2nd proper MTB.

I'm hoping it's not seized to ****!

Oval all round.

Tee hee.

Sheldon Brown describe it well

Biopace chainwheels have the small radius engaged when the cranks are horizontal, the large when they are vertical. This is because the Biopace design is based on a dynamic analysis of the motion and momentum of moving cranks and legs, unlike the static, geometric analysis that produced classical ellipticals.

The theory is that during the power stroke, when the cranks are more or less horizontal, you are using the power of your legs to accelerate your feet, which get going quite fast in the lower gear provided for that part of the stroke. The momentum of your feet then carries the pedals through the "dead spot" when the cranks are near vertical. Since the rider doesn't push as hard during the power phase of the stroke, and motion is slower when the leg is changing direction, the Biopace design is gentler on the knees than even round chainwheels.

The marketers of Biopace made a crucial error of judgment: too much information. In particular, they mentioned that the Biopace design was optimized for cadences of about 90 rpm and slower. Many readers interpreted this as an indication that Biopace chainrings would somehow interfere with pedaling faster than that. This perception caused a bit of a self-fulfilling prophecy, and the Conventional Wisdom arose that Biopace was bad for high-performance cyclists for this reason. I [Sheldon] used to believe this myself, but I rode them anyway because I appreciated their other virtues.

If I could figure out how to make image post here I'd put the image of the biopace shape here. But I can't so I won't. If you head on over to Sheldon browns site you'll see it.

Sweet, thanks @cromolyolly 👍😃

Hth. Although really you shoukd be thanking Sheldon.

Now if someone could just explain why I can't get iamges to appear despite using all the methods in the various threads in "how to get images in posts)

^^ If you are nabbing a pic from another site (and they aren't using wizardry to ago you using the pic) I usually find that by opening the image in a new tab (on my Android) and then copy/pasting that url onto stw (using their IMG tab etc) it usually works fine.

If I really can't get an image to work,I just download it and host it on postage.org which always works.

Hmm. I wonder if it something to do with Android. I've even tried using the img tags manually

I've used an Oval ring for the past couple of years on the t130..
I probably can't remember the difference now ..but less knee pain in the intervening period means I won't go back ..