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Bike component fitment: bottom bracket, headset, seatpost, axle

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Parts ranked by diameter

34.9 mm
34.9 mm seatpost has the highest diameter in the dataset, at 34.9 mm.

Which part has the highest diameter?

34.9 mm seatpost, at 34.9 mm, tops the 6 parts we hold a published diameter for. The full ranking is below.

#PartsDiameter
134.9 mm seatpost34.9 mm
231.6 mm seatpost31.6 mm
330.9 mm seatpost30.9 mm
430.6 mm seatpost30.6 mm
527.2 mm seatpost27.2 mm
625.4 mm seatpost25.4 mm (1 in)

Data as of 2026-09-06.

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