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Join Date: Apr 2015
Location: Morris County, NJ
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Bikes: 90's Bianchi Premio, Raleigh-framed fixed gear, Trek 3500, Centurion hybrid, Dunelt 3-spd, Trek 800
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Remove the chainring and lay it on a flat surface to ensure that it's dead flat. Measure from each spider arm to a fixed point on the down tube or seat tube.