hmm...
You have a lightweight mixte with dual topbars and you attached something akin to a sink disposal motor in wieight to it and have narrow tyres?
Why not use the other gears and get rid of the big thing? I don't see the advantage on that frame, and it's too good to fixie.
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I don't know nothing, and I memorized it in school and got this here paper I'm proud of to show it.