Thread: Saddle Setback Between Sizes
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Old 08-02-16 | 05:14 PM
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79pmooney
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Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

For two frames with different seat angles, the setback will differ by the cosines of the seat angles X the distance from the seat to the BB.

Say one frame is 72.5 degrees and the other 73. Say BB to seat is 75 cm. The difference in setbacks is:

cos 72.5 X 75 - cos 73 X 75 = 22.55 - 21.93 = 0.63 cm. (Multiplying your BB-seat distance times 0.63 and dividing by 75 will get you pretty close.)

Ben
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