Oval Chainring? Gimmick or legit

[NotSoBigBen]

Just now, DieselnDust said:

just remember to raise the saddle and move it forward by the corresponding amount of the crank length change.

Thank you! I'll certainly take note of that

[Bub Marley]

1 hour ago, DieselnDust said:

A much better upgrade for every cyclist is shorter cranks. Even for mountain biking. The phyiological gains are real, and there's science to back it up,......unlike squashed rings

<cue shorter cranks married to oval rings debate>

Im still not convinced on the shorter cranks off road thing. Longer cranks give you better leverage and for really steep and rough trails i feel like you need that extra leverage for traction. This is not based on any scientific analysis. This is just what my brain is telling me.

[Dexter-morgan]

42 minutes ago, Bub Marley said:

Im still not convinced on the shorter cranks off road thing. Longer cranks give you better leverage and for really steep and rough trails i feel like you need that extra leverage for traction. This is not based on any scientific analysis. This is just what my brain is telling me.

My Trek Top fuel came out with 170mm Cranks and it is a large, I cannot tell you if its better, but I think they have done some research before the launch, I am still fat and unfit on my heavy dual suspension.

[GaryvdM]

1 hour ago, Bub Marley said:

Longer cranks give you better leverage and for really steep and rough trails i feel like you need that extra leverage for traction.

You are right that changing the crank length changes to overall gearing. But the idea is when you put a shorter crank on you put bigger chain-rings on so you keep your overall gearing the same.

The benefit from the shorter crank comes from smaller hip angles, not the change in gearing.

[DieselnDust]

6 minutes ago, GaryvdM said:

You are right that changing the crank length changes to overall gearing. But the idea is when you put a shorter crank on you put bigger chain-rings on so you keep your overall gearing the same.

The benefit from the shorter crank comes from smaller hip angles, not the change in gearing.

The gearing actually isn’t affected. Think of a diesel bs petrol engine. Diesel has a long stroke , petrol has a short stroke but but do similar rpm. Think of the shorter stroke as the engine having to fire for a shorter duration but more often so a gearing benefit but a force benefit. 
 

traditionally the thinking was longer levers are better and we used incorrect analogies to explain it. Remember gearing really begins are the point of transfer of the load. So if we consider that to the the hip then we achieve better leverage at the hip already to move the load through a smaller angle but same distance. 
 

oval chainrings do t deliver anywhere near the same level of benefit but you can buy them in purple and that’s so “shiny”

<cue singing crab>

[The itch]

30 year old technology ,it's meant to make your pedaling stroke smoother and more efficient. I had a Panasonic bicycle back in the day. Big blade had a sticker on it  'Biopace' 

[Super Sywurm]

I enjoy my oval chain ring with 175mm cranks.🤷‍♂️

[i24]

54 minutes ago, The itch said:

30 year old technology ,it's meant to make your pedaling stroke smoother and more efficient. I had a Panasonic bicycle back in the day. Big blade had a sticker on it  'Biopace' 

I had Biopace chain rings on my vintage MTB 'till quite recently. I have ridden 10's of thousands of km's on that bike and I still ride it regularly. I replaced them with entry level Shimano rings when the Biopace rings wore out. I can confirm 2 things:

• There is no notable benefit from "oval" chain rings.
• It has 3x7 gears, oval chain rings make setting and using the front derailleur significantly trickier.

[guidodg]

Biopace worked completely differently to modern oval rings and was in fact discontinued after some lawsuits in the US where people reported injuries after using it… it was absolutely crap

[guidodg]

Biopace put the orientation of the oval opposite (roughly 90 degrees) from most modern oval rings. Shimano's research said this would reduce the peak angular velocity of the knee joint, which in turn would help reduce knee problems and make maintaining a higher cadence more comfortable. Many riders found the pedaling feel unnatural. Since the system attempted to solve a problem few riders had, it was unpopular and relatively quickly abandoned.

[Jbr]

I started road with oval chainrings, because that's what was on the bike when I bought it, had tons of chaindrops and issues with shifting between big and small blades.

I also ran ovals on my MTB for years, because I don't know, guess I was told it was better. Eventually went to round chainring because it was more convenient, felt ******* difference, except for less chaindrops while backpedaling (not that I had many either on ovals to be honest).

I'm personnally rather convinced it's a gimmick, haven't had ovals on any of my bikes for years and always am surprised when I seen someone still using them.

I think some youtubers proved more or less convincingly that they could go over technical climbs better with round that oval chainrings 😜. Can't say I've had the same experience.

[GaryvdM]

5 hours ago, DieselnDust said:

The gearing actually isn’t affected.

No. It is affected.

Lets do the math, and test it:
 

The actual MA should be calculated with the radius to the outside of the tire, but I can't attach my scale to that, so just using to the end of the spoke where I can attach it.

I measured 2.65kg when I tested (not using the most accurate of scales.)

 

Now lets shorten the crank:

 

I measured 1.65kg when I tested.

Edited February 11 by GaryvdM
improve

[GaryvdM]

Interesting video on the biomechanical effects of shorter cranks: 

 

[DieselnDust]

1 hour ago, GaryvdM said:

No. It is affected.

Lets do the math, and test it:
 

The actual MA should be calculated with the radius to the outside of the tire, but I can't attach my scale to that, so just using to the end of the spoke where I can attach it.

I measured 2.65kg when I tested (not using the most accurate of scales.)

 

Now lets shorten the crank:

 

I measured 1.65kg when I tested.

 you have correctly explained that the leverage is affected. I wholeheartedly agree

Gearing and leverage are not exactly the same thing. gearing or gear ratio refers to the ratio of driver and driven wheel sizes to amplify or attenuate torque. In leverage we do this to applied force through angles and leverage distance.

I specifically drew in the hip angle effects on the force vectors for this reason. Peak Torque's video explains it nicely. I don't think we are in disagreement though

[nick_the_wheelbuilder]

I can't quote the science behind it, but I'm a huge believer in oval rings and will never ride a round chainring if I can help it.

I was chatting to someone else about this the other day.

I notice little difference moving from a round to an oval ring BUT when switching back, it's very noticable.

On a road bike, when getting out of the saddle to hit a steep climb, with a round ring it feels like the back wheel slips under power.

Strange, I know.

The oval ring's "peak" in the power zone helps and the "squashed" part helps you get through the non-power part of the pedal cycle more easily.

I'm a total convert, never going back to round rings.

[Me rida my bicycle]

I was on 175mm with oval ring for a long time. Changed to round with 165mm crank and my speed improved and I found it easier to keep a consistent speed. Unfortunately my crank gave up after years of use (I used it on 4 bikes) and 165's are so difficult to find so running 170mm for the past year +- not bad but I am missing my 165s.