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May 18, 2018, 9:58 a.m. -  Shoreboy

As Cam said the imaginary line from the BB up to where it intersects the imaginary reach line is the effective seat tube angle \(ESTA\).  Most companies take an average, some actually state the ESTA for each different size of bike.  The actual seat tube angle \(ASTA\) is if you draw a line down the seat tube to the ground and then measure that angle.  Knollys have their seat tube intersection well in front of the BB, so 68 degrees for a ASTA sounds about right.

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