SL8 Seat Clamp Bolt Weight: 7.1 g TiNE vs 19.5 g Stock (12.4 g Off)

The Specialized Tarmac straight-head seatpost is held in the frame by a single titanium bolt — the gold-colored bolt visible at the top of the seatpost clamp in TiNE's reference build. The stock steel bolt weighs 19.5 g. TiNE's direct-fit titanium replacement, sold as a matched bolt-and-nut set, weighs 7.1 g — a 12.4 g saving on the single fastener that locks your saddle height in place.

What This Bolt Does

The bolt threads through the seatpost clamp at the top of the frame, just below where the saddle sits. When tightened, it squeezes the clamp around the seatpost and locks saddle height in place. It's a single fastener doing a single job — but it's also the only thing standing between you and a sudden seatpost drop mid-ride, so it sees real load. Pro mechanics rebuilding race bikes often replace this bolt with titanium for weight savings, since the swap is one-for-one: stock bolt out, TiNE bolt in, torque to spec, ride.

Frame Compatibility

TiNE's bolt-and-nut set is cut for the straight-head seatpost — the round-post design used on the Tarmac SL6, SL7, and SL8. Fitment is determined by the seatpost shape, not the frame generation, so the same bolt also works on any Tarmac (including the SL9) that runs a straight-head seatpost. Riders on the SL9 with the dropped-aero seatpost shape will need a different fitment.

Material and Manufacturing

Grade 5 Ti-6Al-4V titanium, CNC-machined from solid bar stock. The bolt and nut are anodized in eight colors: gold, blue, sugar-color, silver, ink, pink, green, and dream. Color-matched builds on stock SL8 frames are popular — the gold variant pairs well with the rose-tinted raw carbon finish on certain SL8 colorways. For stealth builds, silver blends in with the stock bolt visual weight without drawing attention.

The clamp force required to hold a saddle at full rider weight (roughly 60–90 kg on the saddle) is well within titanium's elastic range. The bolt threads into the frame's integrated nut, and torque values follow Specialized's stock spec — no special procedure required. Riders report no slippage under sprint loads, no saddle tilt migration, and no creaking after hundreds of install cycles.