Egg chainrings, who remembers them?

[DoctorRad]

Nice to see you back Graham!

I have now been using 45% elliptical EggRings for four months. The effect they have when cycling in easygoing flat conditions is minimal. However the greater the resistance to pedaling, be it from an incline, headwind or softground, the more marked the improvement in efficiency over round rings.

You get even more of an improvement when you're carrying luggage.

 

[GrahamJohnWallace]

The optimum gear shape possible would be one were the bicycles speed remains constant during pedalling. With enough torque in the power-stroke to replace the energy lost through air resistance, rolling resistance or overcoming the effects of gravity on a hill, but not that much torque that the bike continuously speeds up and then slows down again during the dead-spot. (you could call this phenomenon power-stroke' "speed bobbing").

However the 'pulse' nature of the bicycle drive chain makes the totally smooth delivery of torque imposible, and the greater the resistance to pedalling forces the more inefficient a round-chainring based system will become. This explains the long held practice amoungst EggRing users of making the chainrings increasingly elliptical from the large to the small cogs. It also explains why very elliptical EggRings work best with a slower cadence, when each stroke is delivering a lot of torque.

DoctorRad wrote: You get even more of an improvement when you're carrying luggage.

Carrying luggage will increase the inertia (resistance to acceleration) of the bike. To overcome this you need the extra torque of a lower gear which could then cause excessive acceleration during the power-stroke and so "speed bobbing". An elliptical chainring could indeed be used to to reduce this effect.

 

[cyfa2809]

The optimum gear shape possible would be one were the bicycles speed remains constant during pedalling.

so like 'mechanical cadence' i.e. the bikes keeps a good pedalling rythm rather than having to do it yourself?

i did mechanical science at college but its damn hard!!!! :evil:

 

[cyfa2809]

the question on my lips is: are egg rings better or not?

 

[GrahamJohnWallace]

cyfa2809 wrote: "the question on my lips is: are egg rings better or not?"

Good Question. The answer is that it depends on the resistance to pedalling effort involved.

With only a little resistance like when cycling along a flat road, there is little or no benefit to using a very elliptical chainring.

With higher levels of pedalling resistance like when climbing steep hills, very elliptical EggRings become more efficient. The climb will be less jerky and you will have used less energy to get you to the top. The less steep the hill, the less elliptical the EggRing needs to be, in order to smooth out the jerks.

This is evident in video footage I have taken of the same 44% hill being climbed, first with a round ring and then a 45% elliptical Eggring.
The EggRing climb appears to be much smoother and the climb took visibly less effort.

The same benefit would also be found when riding soft ground or battling against strong headwinds.

However, no EggRing could be as efficient as the continuous and smooth drive of a good electric motor.

 

[cyfa2809]

electric !!!!!!!!!!

yeah i get it. so generally for flat riding i.e. canal paths save your money and get some round ones. if you go up hills often the benefit is worth the cash

 

[DoctorRad]

This is evident in video footage I have taken of the same 44% hill being climbed, first with a round ring and then a 45% elliptical Eggring. The EggRing climb appears to be much smoother and the climb took visibly less effort.

Can we see this video footage on YouTube please Graham?!? A doubter over on STW said they would like to see someone climbing a 44% gradient...

If you need help editing it into a mini-documentary with suitable music, let me know

Thanks,

Dr. Matt...

 

[sworksm2]

Rotor Q rings on the pros bikes

OK Guys , someone earlier mentioned that if , (I'll use the term non round rings to avoid the debate on shape) Non round rings, were so good how come everyone isn't using them. Well I recently went to have a look at the World MTB Champs in Canberra and guess what I noticed! There were a significant number of top XC racers using Rotor Q rings. So many I had to investigate the possibilty of aquiring some. At about $389 Australian I'm going to wait until I need new rings. I heard figures of 8% more power but can't verify that at this stage. There were lots of Specialized guys using S works carbon cranks with Rotor rings.
I have a feeling everything old is new again and this debate is only just getting going.
The guy at importers tent with the Rotor rings got all worked up when he told me it was all new technology and I mentioned Biopace. (yeah I know the orientation and shape is different but the problem is the same and the approach similar )

 

[DoctorRad]

Re: Rotor Q rings on the pros bikes

Well I recently went to have a look at the World MTB Champs in Canberra and guess what I noticed! There were a significant number of top XC racers using Rotor Q rings. So many I had to investigate the possibilty of aquiring some. At about $389 Australian I'm going to wait until I need new rings. I heard figures of 8% more power but can't verify that at this stage.

To try them on the cheap, get hold of some old BioPace or OvalTech rings and get them correctly orientated. I'll be doing a How-To on this once I have my recently acquired OvalTech set on a bike.

Q-rings seem to have a remarkably similar 'ovality' to the old school rings.

 

[GrahamJohnWallace]

DodtorRad wrote: "Can we see this video footage on YouTube please Graham?!? A doubter over on STW said they would like to see someone climbing a 44% gradient..."

I shot the video in 1080p High Definition, so need find a way of reducing the resolution and file size to one that can be posted online.

My EggRing geared bike has only once failed to climb my 44% benchmark hill. This was when the rear wheel slipped on some loose chalk near the top.

I am now looking for a slightly steeper short hill of average 45% or 46% gradient, in order to find were my bikes' climbing limit is.