Twin-Bolt Aero Seatpost Saddle Clamp

A stronger, rail-safe alternative to the Ritchey WCS 1-Bolt clamp

Designed for time-trial and triathlon bikes that use a cylindrical aero seatpost interface. This clamp replaces the stock Ritchey-style 1-bolt assembly with a twin-bolt design that holds saddle rails the way they were meant to be held.

Each clamp is made to order. Production typically takes 7–10 business days, including metal 3D printing and post-processing (sand blasting + annealing).

The Problem

The Ritchey WCS Alloy 1-Bolt clamp compresses saddle rails from the sides — like squeezing a hot dog. That sideways pinch:

• Bends the rails in a direction they were not designed to handle
• Increases the chance of rail damage over time
• Can allow the saddle to slip downward after a hard impact or bump

On wide aero seatposts (Colnago TT1, Cervélo P5, Factor Slick, and similar), that slip is especially frustrating because the rest of the interface is otherwise solid.

Right now, the only common way to get a proper twin-bolt clamp on some of these TT frames is to replace the entire seatpost with a lightweight aftermarket post from companies like Darimo. That can cost around €500 or more for a ~50 g weight saving — and those posts often sacrifice saddle adjustability. Not everyone wants to buy a new post just to fix the clamp.

The Solution

This clamp keeps the same OEM seatpost interface you already have, but changes how the saddle is held.

• The base still bolts to the cylindrical rod that sandwiches the carbon seatpost (same M5 hardware that came with your bike)
• The upper clamp uses two M6 bolts and sandwiches the rails from top and bottom — like a burger, not a hot dog
• Rails stay straight. Clamping force is applied in the correct direction
• Twin-bolt design also gives you pitch adjustment while keeping a secure hold

You keep your existing OEM aero seatpost, keep full saddle adjustability, and get a twin-bolt rail clamp — without paying for a full aftermarket post.

No more side-loading the rails. No more unexpected downward slip after a bump.

Two Versions — Choose Based on Your Saddle

At checkout, select the version that matches your saddle so you receive the correct stainless thread pieces:

Version 1 — Saddle with cutout

• Uses standard M6 hex bolts
• Bolts install from the top, down through the saddle cutout
• Tightened from above through the cutout

Version 2 — Saddle without cutout

• Uses M6 hex-head bolts
• Bolts are installed upside down and tightened from below with a wrench
• Required when there is no cutout to access bolts from the top
• Saddles without a cutout have more difficult installation compared to saddles with cutout. For example, Wove V8 (in pictures) has difficult initial fitment due to the design of wings of the saddle. 

The aluminum clamp body is the same. Only the threaded stainless pieces change between versions.

Ensure you select the correct kit at checkout: 

• Whether your saddle has a cutout or not
• Whether you would like additional cylinder mounting threads (m5 threaded piece that goes in the seatpost itself)
• Whether you want Full Kit (hardware for with/without saddle cutout & replacement cylinder mounting threads)

Hardware Notes

• M6 bolts are not included. Any standard stainless steel M6 bolts will work.
• Choose bolt style based on the version above (standard hex bolts for cutout saddles, hex-head bolts for non-cutout saddles).
• Reuse your bike’s existing OEM M5 bolts for the seatpost-interface / base clamp.

Materials & Construction

- Main clamp body: AlSi10Mg
- Threaded pieces: 316 stainless steel
- Seatpost interface bolts: OEM M5 bolts (reuse from your bike)
- Rail clamp bolts: Customer-supplied M6 stainless bolts, standard hardware that is easy to source locally

Compatibility

Designed for aero TT / triathlon seatposts that use the cylindrical-rod + sandwich-base interface, including:

• Colnago TT1
• Cervélo P5 and P-Series
• Wilier Supersonica SLR
• X-Lab DB01
• Cube Aerium
• Lapierre Aerostorm
• Bianchi Aquila RC
• Cannondale Super Slice 2019-2025
• Cannondale Super Slice 2026-Present
• Factor Slick
• Ridley Dean Fast (rim & disc), Arena Fast, and Omnium Fast
• Scott Plasma RC 
  

Also compatible with other road or TT frames that use the same seatpost clamp interface.

If you’re unsure whether your post matches, send a photo of the seatpost head and clamp area and we’ll confirm before you order.

What’s Included

• 3D-printed aluminum main clamp body (AlSi10Mg)
• 3D-printed 316 stainless threaded pieces (selected version: cutout or no-cutout)

Not included: M6 bolts (purchase separately — any standard stainless M6 bolts)

Production & Lead Time

Every clamp is printed to order — not stocked.

• Metal 3D printing in AlSi10Mg and 316 stainless
• Post-processing: sand blasting + annealing
• Typical production time: 7–10 business days after order confirmation
• Shipping time is additional

Fit Notes

• Designed for TT / triathlon aero seatposts with the cylindrical rod interface
• Twin-bolt layout allows saddle pitch adjustment
• Rails are clamped top-and-bottom to avoid side-bend

• Contact us with photos of your seatpost and saddle if you want compatibility confirmed first.