First elliptical rings, then osymetric rings and now...

[Mr Haematocrit]

Rugby ball rings

If you already thought Rotor Q-Rings or Osymetric chainrings were unusual looking, turn away now. Rosset Ogival's take on non-round chainrings is far more radical with their (American) football shape and decidedly pointed ends. Despite appearances, the basic thinking behind them is similar to that of Rotor and Osymetric, which is to increase the effective gear ratio where you're putting out the most power but decrease it in the dead zones in order to facilitate a smooth and efficient pedal stroke. We have a set of road-specific Rosset Ogival chainrings on hand here but the company also offers mountain bike versions – including a thick/thin variant for SRAM's XX1 drivetrain.

€56-109 each

www.ogivalring.com

 

[Smurfy]

Can I use that on fixed-wheel?

 

[Mr Haematocrit]

Can I use that on fixed-wheel?

They have one for the single ring gear SRAM XX1 group set, so I can't see why not.
Would you want to try it then?

 

[Andrew_Culture]

In all seriousness I'd rather put one on my SingleSpeed than smash my front changer on my geared bike!

 

[Andrew_Culture]

Hang on, am I being daft or would they plain and simple just not work on a fixie?

 

[Mr Haematocrit]

Hang on, am I being daft or would they plain and simple just not work on a fixie?

I've no idea, but I would be interested in your reasoning

 

[edindave]

Hang on, am I being daft or would they plain and simple just not work on a fixie?

Wouldn't work. At two points in a pedal stroke the chain would be so slack it would be trailing on the ground.

If you check your current fixed you'll see what difference there is in chain tension at various points in the crank rotation and that's with the minor irregularity of a circular ring.

 

[Mr Haematocrit]

The XX1 SRAM has a single ring gear with no chain catcher or mech and it works on these, could you not use the same on a fixie?

 

[themosquitoking]

Are you thinking of lose chain issues?

 

[Mr Haematocrit]

Wouldn't work. At two points in a pedal stroke the chain would be so slack it would be trailing on the ground.

If you check your current fixed you'll see what difference there is in chain tension at various points in the crank rotation and that's with the minor irregularity of a circular ring.

Yay and someone saves me from my stupidity.... My hero, nice one
I forgot about the rear much taking up chain slack.... Doh

 

[edindave]

I'm guessing it has some sort of chain tensioner type component?

 

[youngoldbloke]

In all seriousness I'd rather put one on my SingleSpeed than smash my front changer on my geared bike!

- just how could a front changer work with those?

 

[Smurfy]

- just how could a front changer work with those?

With a lot of crunching and grinding noises?

 

[Smurfy]

Wouldn't work. At two points in a pedal stroke the chain would be so slack it would be trailing on the ground.

If you check your current fixed you'll see what difference there is in chain tension at various points in the crank rotation and that's with the minor irregularity of a circular ring.

The 'minor irregularity' problem is due to eccentricity. If the rugby ball shape always has the same number of teeth engaged then no problem provided it is concentric with the bottom bracket.

The late Sheldon Brown claims to have run Biopace rings on several fixed-wheel machines (see 'The Cadence Issue' at this link). I'd give the rugby ball a go on fixed, but only if it was free to try.

 

[mickle]

I'd like to see a picture of of them on a bike with a front derailleur. Also - I bet the teeth at the ends wear out really quickly.