I know that there were many before these, but I'm a big fan on oval rings: Biopace on my Roberts, Chris Bell on the Fat Ti, these type ones on the Turner from time to time. Just got to make sure they are correctly oriented - 90 degrees around from shimano's orientation to work properly.
Load more info here: http://www.highpath.co.uk/cycles/ovals/01.html
(quality beardy stuff...)
Load more info here: http://www.highpath.co.uk/cycles/ovals/01.html
(quality beardy stuff...)