Oval chainring no good on some frames?

Wondering if anyone else has noticed certain frames that seem to lose power with an oval chainring.

I tried out oval a year or two ago and have since switched to oval on all my bikes when they need replacement. Recently got a new rig and found it to be an inefficient pedaller compared to my other bikes. Even others with much more travel. Switched to a round ring (same number of teeth) and it is much better. I wonder if the high point on the oval was at the right height to compress the suspension more so than on my other bikes? The weird thing is that my other bikes have 32 tooth Crings and this one is a 28 so I would have expected less suspension activation.

Anyone else find certain combo's not as good as others?

You may be right about certain platforms not being oval friendly. I’ve tried oval myself extensively. Rotor two by on my mountain bike and road bike. And a One up on my off road bikes. When I got a new hardtail a couple years ago it came with a round ring so I figured I’d just use that until it was done. I noticed that it made no perceptible difference in my ability to ride things. I could feel the difference in pedalling but not in performance if that makes sense. 

Some high profile pro road riders use it like Froome and Wiggins but I’ve read that the testing Sky/Ineos did showed no measurable improvement in performance. But since the riders liked it, they continued to use it.

I'm the same way. I have tried a bunch of oval rings and don't really notice anything different in terms of performance vs. round. On the bikes I have used ovals I have not had issues with how they pedaled.

I like the ovals for standing climbing - especially over gnar. Gives you that extra bit pushing over the top when on a steep. On the Kona, the bike has felt like it sapped energy from pedal strokes ever since I got it. I did notice more pedal bob than on my other bikes but thought - nah, must be in my head. Took the round ring out for a lap on Maple syrup in Duncan. The bike feels completely different. It is lively and efficient. The suspension feels more active. It is more solid feeling when climbing standing. Round rings on the Kona from now on.

I found the oval on my Spartan 27 was really noticeable in how the suspension performance changed when feet were at 3 and 9 oclock. I've had one suspension designing tell me it's in my head, but then subsequently talk about how much ring size does change performance, so I feel there's something in it. I went back to a round ring and it  was better.

I've since put an oval on my 29" Spartan and it's less  noticeable. I'm running less sag than on the 27" so I'm curious if that's offsetting it.

I used an oval on an FSR style bike and did not love it. I think a bike with a higher AS would have been a better fit, and a HT would have been the ideal bike.

Posted by: RAHrider

I like the ovals for standing climbing - especially over gnar. Gives you that extra bit pushing over the top when on a steep.

That was my experience running an oval on my hardtail. Really slow speed tech moves when climbing, just as I would usually stall out and dab on a round ring, the oval seemed to pull me through those sections.

So I think I've noticed that odd bit of performance enhancement, but I don't perceive the oval otherwise while pedaling under normal circumstances.

I haven't noticed much running the 28t oval on my Trance yet.

Posted by: Heinous

I found the oval on my Spartan 27 was really noticeable in how the suspension performance changed when feet were at 3 and 9 oclock. I've had one suspension designing tell me it's in my head, but then subsequently talk about how much ring size does change performance

Were you noticing this 3/9 o'clock performance change while descending? The chainring size/shape effect should only be an issue while actively pedaling, when your feet are fixed in descending position it should have no bearing.

I really can't describe how shit the oval ring felt on the Kona Process 134. I wondered if it was due to the height of the pivot being too low but my Knolly is even lower and it gets along great with the oval. So now I'm wondering if it is also related to single pivot vs horst link. Even though the pivot is low on the knolly, the chainstay doesn't shorten as it moves through the initial travel due to the horst link whereas on the single pivot Kona, once you get to a certain point, chain tension will activate the travel. Wondering if that's what is going on? Perhaps it would have been better if I ran less sag?

Posted by: UFO

Posted by: Heinous

I found the oval on my Spartan 27 was really noticeable in how the suspension performance changed when feet were at 3 and 9 oclock. I've had one suspension designing tell me it's in my head, but then subsequently talk about how much ring size does change performance

Were you noticing this 3/9 o'clock performance change while descending? The chainring size/shape effect should only be an issue while actively pedaling, when your feet are fixed in descending position it should have no bearing.

Yeah, when I was pedalling quickly descending and weighting it, and also noticed it felt almost like faster rebound when climbing tech stuff at times.

I’ve run them for years on my SS’s and other bikes so it surprised me. It’s been much less noticeable in my 29, which I’m running around 24% sag instead of the 30% on the 27”.

I went down 2 teeth from 30 to 28  when I got the absolute black chainring so I wasnt comparing apples to apples so I can't say for sure, I  probably wouldnt have bothered going oval unless i needed a smaller ring