Egg chainrings, who remembers them?

[DM]

OK, well the sum of the parts is quite odd!
Maybe it's the height of the bars, being above the saddle?

How high is the bottom bracket?
Is there any drop at all from the axle to BB?

 

[GrahamJohnWallace]

DM wrote: How high is the bottom bracket?

Is there any drop at all from the axle to BB?

Geoff will have the spec for the Cleland TT. But judging by this Highpath Engineering' drawing from 1988, the answer is probably not much!

 

[GrahamJohnWallace]

My latest thinking on using very elliptical rings is to use a triple chain-set with elliptical inner and middle, and a round outer for those occasions when you need to spin at a high cadence. However, finding a front changer that can handle the change in radius from the minor axis of a 23 tooth elliptical to a 48+ tooth round will be tricky. The elliptical middle ring should have about 40 teeth and is wonderfully suited to low cadence, out of the saddle, honking.

For more info on Modern Clelands follow this link.

http://www.retrobike.co.uk/forum/viewto ... ht=cleland

 

[DoctorRad]

Looks like someone else has had the same idea as me, namely that laser-cutting elliptical chainrings would be a great way to do low / custom production:

http://forum.ctc.org.uk/viewtopic.php?f ... 1&p=632018

What I can't work out is how to place the tooth cut-outs for a given number of teeth and eccentricity. It gets easier if the number of teeth is a multiple of four (or two) but it's quite a hard problem from where I sit... anyone have any clues?