Layup Schedule

Summary

A layup schedule is a detailed plan that defines the number, orientation, and placement of composite fiber layers—typically carbon fiber—used in a bicycle frame or component. It directly controls the structure’s stiffness, strength, compliance, and weight distribution, making it a foundational aspect of carbon bike engineering.

Key Facts

  • Introduced: 1980s (adopted from aerospace engineering)
  • Category: Technology / Manufacturing / Concept
  • Also known as: Layup chart, layup matrix, fiber schedule
  • Used by / Found on: Carbon bicycle frames, forks, rims, cockpits, and small parts
  • Core function: Controls mechanical behavior and manufacturing precision
  • Materials involved: Prepreg carbon, aramid, fiberglass, hybrid laminates
  • Managed by: Composite engineers and material technicians

Overview

In carbon fiber manufacturing, the materials themselves tell only half the story. Two bike frames may be made from “T800 carbon,” for example, yet feel completely different on the trail or tarmac. That difference often comes down to how the material is used — and specifically, the layup schedule.

The layup schedule is the structural blueprint for a carbon fiber component. It details exactly how many layers (or “plies”) of material go into each section of a frame or part, what direction the fibers are oriented, how those layers are stacked, and where overlaps or reinforcements are needed. It’s like an architectural plan for the internal skeleton of a composite product.

Each ply in the layup has a specific purpose. Some resist torsion, others reinforce high-load areas like the head tube or bottom bracket. Some add compliance to the seat stays, while others help control flex at the fork crown. The schedule organizes these layers into a roadmap for manufacturing — one that ensures every part performs as intended, not just in terms of stiffness and strength, but in ride feel and longevity as well.

What sets high-end carbon frames apart is often not the material itself, but the refinement and complexity of their layup schedules. Brands with deeper composite expertise, or access to aerospace-grade engineering, can fine-tune ride characteristics with surgical precision. That’s why the best layups aren’t just strong — they’re expressive.

How It Works

A layup schedule begins as a design document, typically created by a composite engineer using CAD software and simulation tools. It is translated into a table or chart that maps out each layer of the composite structure.

1. Ply Specification

Each ply is defined by three primary parameters:

  • Fiber orientation: The direction the fibers run — typically in angles like 0°, 45°, 90°, or -45° relative to the axis of the frame.
  • Material type: Different grades of carbon (T700, T800, M30, etc.), or hybrid materials like aramid or fiberglass, depending on the area’s needs.
  • Placement and shape: The exact cut of the sheet and where it fits in the mold.

Ply orientation is fundamental. A 0° ply adds stiffness along the length of a tube, while ±45° plies help resist twisting. By varying these directions and stacking them carefully, engineers create a tailored laminate that balances strength, stiffness, and flex.

2. Region-by-Region Planning

The schedule breaks the component down into zones — for example:

  • Head tube: Needs high torsional stiffness and impact strength
  • Top tube: Requires vertical compliance with lateral rigidity
  • Seat stays: Often tuned for vertical flex to improve comfort
  • Chainstays and BB shell: Must withstand pedaling forces and lateral loads

Each zone has its own sub-layup, with specific instructions for ply counts and orientations. Some premium frames may feature over 500 pieces of carbon in a single frame, each meticulously planned.

3. Symmetry and Balance

Engineers also ensure laminate symmetry to prevent warping, distortion, or residual stresses. For instance, if a ply at +45° is added on one side of the tube, a corresponding -45° ply is often mirrored on the other.

4. Manufacturing Execution

Once the schedule is finalized, layup technicians follow the plan — either manually or via semi-automated machinery — layering each sheet into the mold in precise order. The part is then molded (often using bladder molding), cured, and inspected.

Quality control is essential. Any deviation in ply orientation or placement can compromise performance or lead to structural failure.

Importance in Frame Design

The layup schedule is one of the most powerful levers a designer has to tune ride characteristics. It’s what transforms raw carbon into a bike that climbs crisply, descends confidently, or smooths out rough terrain. Here’s how it shapes performance:

1. Stiffness-to-Weight Optimization

By varying the number and type of plies, engineers can reinforce critical areas while trimming unnecessary mass elsewhere. This is especially useful for race bikes where every gram counts.

2. Ride Feel Tuning

Not every frame needs to be a board-stiff race machine. Endurance bikes, gravel rigs, or trail frames benefit from compliance zones — areas designed to flex slightly for comfort or traction. The layup controls this behavior down to the ply.

3. Fatigue Resistance

Proper ply arrangement helps distribute stress evenly through the frame, reducing hot spots that lead to cracks or fatigue over time.

4. Size-Specific Design

Some brands tailor the layup by frame size, so that stiffness and flex scale properly with rider weight and geometry. Larger sizes may receive extra plies in key zones for this reason.

Notable Implementations

  • Cervélo RCA: The company’s halo project used a highly optimized layup schedule to create a 670g frame with elite stiffness and ride quality.
  • Specialized S-Works Tarmac SL7: Features a size-specific layup schedule tuned for different rider weights and stiffness targets.
  • Santa Cruz Blur: Santa Cruz uses dedicated layup engineers to fine-tune frame feel across models and sizes.
  • TIME Alpe d’Huez: TIME’s RTM layups are built layer-by-layer with aerospace precision.
  • Look 795 Blade RS: Layup is combined with RTM molding for high-fidelity frame production.

Related Terms

References

  • TIME Sport Layup Engineering Docs
  • Cervélo RCA Project White Paper
  • Santa Cruz Composite Engineering Overview
  • Composites World: Carbon Layup Techniques
  • Specialized Carbon Engineering: SL7 Technical Sheet
  • Look Cycle Manufacturing Background
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