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

[edindave]

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.

That's very interesting. Must admit it surprised me a bit that the number of teeth, and not the shape of the ring, is the key factor.

 

[solidthegreat]

Dude, are you on a wind up? How in the name of all that is pure and good do those work. Surely the chain would jump at half revolution.

 

[RecordAceFromNew]

Hey guys don't knock it, considering how young Stewie Griffin is, to have designed it.

 

[Smurfy]

That's very interesting. Must admit it surprised me a bit that the number of teeth, and not the shape of the ring, is the key factor.

I'm not sure. Maybe the rugby ball shape is too extreme. Here's what Sheldon said about Biopace on a fixed-wheel setup (same link as before):

Biopace and Fixed Gear
People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain tension as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.
There is a slight variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.

 

[Gravity Aided]

http://velobase.com/ViewComponent.aspx?ID=a3f7d39a-d7e2-4775-be62-620152fd416f&Enum=122
Been done before

 

[slowmotion]

Isn't your chain going to get FUBARed from going over such irregular angles on the teeth?

 

[Mr Haematocrit]

http://velobase.com/ViewComponent.aspx?ID=a3f7d39a-d7e2-4775-be62-620152fd416f&Enum=122
Been done before

That reminds me more of osymetric rings personally, they seem to have less extreme appearance than the rugby ball shape

 

[Mr Haematocrit]

I'd give the rugby ball a go on fixed, but only if it was free to try.

Just ordered a set as im really curious, when I'm finished playing your welcome to try them if your iinterested.

 

[Dusty Bin]

I'm waiting for the square ones to come out....

 

[Smurfy]

Just ordered a set as im really curious, when I'm finished playing your welcome to try them if your iinterested.

A set! I presume you've already tried all the other non-round offerings?

 

[02GF74]

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.

as long as the number of teeth engaged is the same, then the shape should not matter ... and a quick look at them rings seems to indicate it is the same.

 

[Mr Haematocrit]

A set! I presume you've already tried all the other non-round offerings?

Yea pretty much, if your interested in having a play with any, I can send you a set.. Not tried any on a single speed though

 

[Smurfy]

Yea pretty much, if your interested in having a play with any, I can send you a set.. Not tried any on a single speed though

I think they'll probably be a bit extreme for fixed, maybe better for single-speed. I'll be interested to hear how you get on, and any comparisons with the other non-round options. My next single-speed project will be an MTB, which I'll be working on and buying parts for over the next few months.

 

[fossyant]

Gadzooks, they are ugly, never mind rotor stuff. Nothing so ugly shall ever adorn my road bikes.

 

[fossyant]

Won't work well at all on single speed with a chain tensioner mechanism as most of these are fixed in place, rather than are sprung like a rear mech.

Technical issues aside (and there are many) the pedalling motion won't be smooth. On a fixed, dead spots are removed due to the nature of the flywheel