HI Seca,

The diameter of the center holes for sprockets for Top Hat Adapter use have a center hole of approx 2.153"....yes, 9 hole mounting works OK with 36 spoke wheels....Sprocket mounting to minimize wobble and run out can be tedious and time consuming using the factory mounts....using the stock sprocket before mounting another sprocket is no biggie....just a little extra "fun" ;-)

Hope this helps you.

Andrew

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