The SP33 Carbon Seatpost is Cervelo's proprietary D-shape post, the piece that drops into the aerodynamic seat tube opening on the Caledonia-5, R5, and R5CX. This is not a round 27.2mm post, and that distinction matters before you order: the D-shaped profile matches the shape of the seat tube itself, so a standard round post will not fit these frames regardless of diameter. If you've cracked a post in a crash, need a spare for a travel build, or want to change your setback, this is the current-generation replacement for the exact frames listed below.

Fitment is specific and worth confirming. Cervelo lists the SP33 as compatible with the Caledonia-5 (2021-present), the R5 (2017-present), and the R5CX (2023-present). The D-shape delivers vertical compliance that a round post in a round tube can't match, flexing fore-aft to take the edge off rough pavement, and the profile keeps the saddle facing forward in a crash rather than rotating in the tube. Carbon construction handles the vibration damping that adds up over long days in the saddle.

Offset is the other decision to make. The SP33 comes in two versions: a 0mm offset that positions the saddle rails over the post centerline for riders who sit forward, and a 15mm offset that moves the saddle rearward for a more traditional road position. Confirm which setback your fit calls for before ordering, since the two are separate parts. The post ships complete with the head assembly, so there's no separate clamp purchase to track down.... Read More