King of the Hipsters
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
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"All of this leads me to believe that the EAI cog must be a couple of millimeters thicker than the Dura-Ace."
Sheldon Brown has an online table somewhere that gives the thickness of the various manufacturer's cogs.
I have three cogs by three different manufacturers (Soma, Dura Ace and EAI), and they have significant differences, not only in oveall width, but as to where the center line of the cog teeth falls in the overall width.
If I put all three of them on a flat table, the teeth don't line up in the same plane with each other, and dramatically so.
The same applies to the two chainrings.
They not only have a different overall thickness, but the stock Sugino chainring has slightly biased teeth, so that flipping it over could move the teeth left or right, but I find the whole design so assymetric and confusing I can't tell.
The Sugino/SR chainring sold by Harris (43t, 45t, 47t, 50t and 52t) has a completely different and symmetrical design, very simple in nature; it seems intended as a track ring and of much better quality than the stock ring.
This combination and placement of chainring and cog represents a happy accident.
I didn't do this intentionally, and only noticed it after playing with the parts for awhile.
With the EAI cog and the Sugino/SR chainring, it only works with the cog flange against the hub and the chainring in the outboard position.
I suspect other cog orientations, chainring sizes and chainring postions on the star will acheive the same result.
This one, however, works and I wanted to report it.
Also, putting the chainring on the outboard position of the star makes enough room for even a 52t chainring to clear the chainstay.
I haven't put a 52t ring on to verifiy this; it just looks like will fit, easily.