Egg chainrings, who remembers them?

[GeoffApps]

During the "klunker" era, when we tried everything we could find, I used a Durham oval chainring as the inner ring with a round outer.

It shifted easily, but I found that whichever shape you had been on for a while, the other felt weird.

Of course I tried Biopace in the '80s. I haven't tried the Eggs, but the general problem with anything but round rings is when you are hitting your RPM limit at high speed. Your feet accelerate and decelerate twice per revolution and a high-speed spin is impossible.

I believe that the practical purpose of the high cadence technique is to reduce the effects of the dead spot by whizzing through it.
However, my experience has been that, once the difference between the power stroke and dead spot has been ironed-out to some extent, there is much less need to spin the pedals. Therefore, it is my view that with a well designed set up, which the rider understands, introducing round rings into the system is not appropriate.

As human beings riding bicycles, we are all different, and yet all adaptable.

 

[GrahamJohnWallace]

I do remember Shimano Biopace BITD, my Muddy fox came with them. Does anyone know why there was a return to round rings if Biopace/oval rings were that good?

The Shimano Biopace rings were next to useless. The rings were oriented the wrong way round so that the gear was lowest during the power stroke and highest at the dead-spot. They did a lot of damage to the reputation of elliptical gear systems.

EggRings are correctly oriented and the ellipse is rotated at 90 degrees when compared to Biopace. The minor axis of the ellipse needs to be lined up to the dead-spot. However the exact position of the dead-spot can change with the type of bicycle. EggRings can also be made to be much more elliptical than Biopace ever were.

 

[Caramba Kid]

Re: Superb stuff

I did some testing about 10yrs ago with some singlepivot suspension bikes, and found that eggrings could eliminate bob, increase traction - really good.

We ran something on it in mbr.......

I remember that mbr article! Was on a Cannondale Raven & verdict was that they almost totally eliminated pedal induced bob

May have to give them a go on my new arrival

 

[cyfa2809]

what is a deadspot on an eggring? is that where the power comes from the curve and steadys where it isnt curved? like a cam?
what is wrong with biopace?
what is the difference between biopace and eggrings?
what are the advantages and disadvantages of eggrings over standard round rings?

 

[GeoffApps]

Now I'm going to get really pedantic:
If you look at the Osymetric website http://www.osymetric.com/index.php?option=com_frontpage&Itemid=40
there you'll see genuine OVAL chainrings. Oval means two semi-circles separated by a rectangle. Think about a speedway track.
This is not to be confused with elliptical chainrings which have a continuous curve between the major axis and the minor axis.
Chris Bell nevertheless uses the term 'ovality' to describe the difference between the major and minor axis. (or should that be axese?).
As he said to me, "ellipticality is a bit of a mouthful".

 

[GeoffApps]

what is a deadspot on an eggring? is that where the power comes from the curve and steadys where it isnt curved? like a cam?
what is wrong with biopace?
what is the difference between biopace and eggrings?
what are the advantages and disadvantages of eggrings over standard round rings?

Read the most recent previous posts again.
Perhaps printing them out and reading them with a nice cup of tea can help when trying to get your head around an unfamiliar technical topic.
That's what I do, anyway.
If you still haven't got it, you may like to phone me up and I'll go through it step by step, if you're genuinely interested.

 

[GrahamJohnWallace]

Geoff Apps said: "I believe that the practical purpose of the high cadence technique is to reduce the effects of the dead spot by whizzing through it.
However, my experience has been that, once the difference between the power stroke and dead spot has been ironed-out to some extent, there is much less need to spin the pedals. Therefore, it is my view that with a well designed set up, which the rider understands, introducing round rings into the system is not appropriate."

The answer to whether it is most efficient to spin or push the pedals is surely measurable in terms of power output and oxygen consumed. EggRings do make slow cadence pushing or 'honking' more efficient and round rings are smother when spinning fast. I suspect that with the dead-spot reduced, slow cadence pushing may be more efficient. This is because it is a more natural form of movement, similar to walking up hill. An activity that the human leg evolved to do and so one to which are bodies will be well adapted.

 

[legrandefromage]

I've got various Shimano rings at home and the Sugino versions

I'll try to remember to do a side by side comparison, the early shimano is more pronounced than the run-out version. The Sugino is 'Oval-tech' if my Mythos addled brain remembers correctly - http://www.mythosbrewery.gr/index.asp?c=4

 

[lewis1641]

I've got some of these in my recently acquired box of bits. I think i will give them a try- i'm a pusher rather than a spinner so they may be a benefit

 

[GeoffApps]

I've got some of these in my recently acquired box of bits. I think i will give them a try- i'm a pusher rather than a spinner so they may be a benefit

Good luck ~ be sure to get the correct orientation of the ellipse ~ the major axis should be about 90 degees to the crank. Look at the photos in previous posts.
Let us know how you get on...