I'm hoping somebody knows what's what with small granny gears.
My tourer is fitted with a 74mm BCD, 26 tooth ring on the front. The cranks are made by Sugino and the rings are aluminium. I'd like to change the granny gear to a smaller, ideally, steel 24t ring, for lower gearing and better durability.
I don't know whether all 74mm rings are interchangeable/compatible. The bolt holes on Sugino rings are slightly recessed or countersunk, ie. the top of the bolt sits almost flush with the surface of the ring when fitted. I wonder if all chainrings are the same and if other brands will fit properly?


