Old 11-21-13, 04:37 PM
  #2  
HillRider
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Join Date: Aug 2005
Location: Pittsburgh, PA
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Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

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The ERD is NOT the same as the ISO diameter and will vary with the rim's depth, nipple seat location, etc. Using just the ISO rim size will give you a wildly wrong spoke length. If the rim manufactures doesn't provide the ERD dimension, there are ways of measuring it. Do a Google search for "Bike rim ERD measurement" and you should find the method.
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