A seatpost must match the frame's diameter and section; a dropper also needs a cable route. Diameter is read to a tenth of a millimetre, and a D-shaped or proprietary section takes only its own post.
- How do I know whether a part in this category fits my bike?
- Every part page lists the standards it requires and its computed verdict on each bike in the fleet, with its confidence and sources. An "unknown" verdict means we do not have the measurement on file — not that it fits.