Oval chainrings???

[Venod]

Never used them, but I have a further question; do they make the position and operation of the front derailleur rather problematic?

No, makes no difference to the operation, changes just the same as roundrings.

 

[I like Skol]

No, makes no difference to the operation, changes just the same as roundrings.

But you do have to set the clearance at the highest point of the oval. Will get rub and binding otherwise and could potentially mangle a perfectly good front mech during a gear shift.

 

[Venod]

But you do have to set the clearance at the highest point of the oval. Will get rub and binding otherwise and could potentially mangle a perfectly good front mech during a gear shift.

Of course

 

[I like Skol]

Of course

You probably wouldn't believe the number of people that do not understand such concepts. Crikey, I am starting to sound like MrBeanz!!!

 

[The happy cyclist]

Never used them, but I have a further question; do they make the position and operation of the front derailleur rather problematic?

Great question! I hadn’t thought about that to be honest

 

[I like Skol]

Great question! I hadn’t thought about that to be honest

You sir fail the Beanz test!

 

[Crackle]

I'm not absolutely sure but I think Froome still races on oval chainrings. Of course he's a pro athlete and has a team of mechanics to sort his bikes, I'm not sure the rest of us would gain the same advantage they might give him or could be bothered with the faffage.

 

[derrick]

I have been using Rotor Q rings for years. Love them never had a problem with front Mech. But I do use Di2. The only time I feel like the difference is when riding someone else's bike which has round rings.

 

[The happy cyclist]

I'm not absolutely sure but I think Froome still races on oval chainrings. Of course he's a pro athlete and has a team of mechanics to sort his bikes, I'm not sure the rest of us would gain the same advantage they might give him or could be bothered with the faffage.

Well he doesn’t ride by the book in fairness with the way his arms are spread

 

[KneesUp]

The Shimano Biopace ones had the timing wrong the Absolute Black rings are different giving better advantage on the power stroke, I have some Biopace on an old MTB, I have indexed them to be more usefull.


View: https://www.youtube.com/watch?v=A557LYuFkSM

The timing was not wrong on Biopace, it was different. I like them, and shall be sad when mine wear out - although I admit I was taken in by the 'they're back to front' argument way back when they were new, and swapped mine out (for a Shimano 600 chainset I bought off a mate for a bargain price and was bloody lovely) I think they weren't marketed very well. Lord Sheldon has this to say:

To a casual glance, Biopace chainwheels resemble elliptical chainwheels, but on closer examination they turn out to be the opposite of the classical elliptical design. The product of extensive research and computer-aided design, 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.

Biopace chainwheels are particularly suitable for touring cyclists and time trialists, or any application that involves a steady, fairly constant cadence. They allow healthy, efficient pedaling at slower cadences than is possible with round chainwheels.​

https://sheldonbrown.com/biopace.html

 

[GuyBoden]

I still have a biopace on my good 1980's Racer, I've also had the ovaltech copy.

 

[KneesUp]

I still have a biopace on my good 1980's Racer, I've also had the ovaltech copy.

I presume you can just roatate a biopace ring to make it wotk the 'other' way, and vice-versa?

 

[GuyBoden]

I presume you can just roatate a biopace ring to make it wotk the 'other' way, and vice-versa?

I presume so, but I've never tried.

They do have a notch thing look here:

 

[KneesUp]

I presume so, but I've never tried.

They do have a notch thing look here:
View attachment 480283

Yes - I have 2/3 Biopace on my bike - I had to replace the middle ring, so that's now round. I don't really notice any difference, unless I'm thinking about it.

 

[fossyant]

It's the latest 'fad' with MTB's. Not for me. Don't like wobbly things.