Weaving

Weaving of Bike Bag’s Fabrics

We zoomed in on yarn manufacturing processes, now we’re zoom out to look at the big picture of the fabrics that these yarns are woven into. Actually, we’re mostly zooming in here as well, as we examine all of the processes that go into weaving the fabric of the bicycle bags we know and love. Beginning with setting up the yarn for the looms, continuing onto how the weaving process works with a variety of style of looms, then considering how this leads to the various weave patterns and wrapping up with fabric measurements.

As with our yarn guide this guide will focus on the weaving processes utilized for nylon, polyester, and UHMWPE fabrics. The weaving process significantly influences the performance characteristics of bike bag fabrics, including strength, durability, water resistance, and overall appearance. By understanding these processes, we’ll grow our knowledge of how different weave structures and techniques contribute to the amazing functionality and reliability of the bicycle bags we sell here at Campfire.

Yarn Preparation

After yarn is manufactured, packaged and transported to a weaving facility, it undergoes several steps to prepare it for the weaving loom. This critical phase ensures the quality and consistency of the yarn before it enters the weaving process, leading to smoother more efficient weaving operations as well as contributing to the quality of the resulting fabric.

Winding

The winding phase is where the weaving operators first take-over responsibility for the yarn, receiving it from the spinning phase and preparing it for weaving. The first step is taking the yarn packages and rewinding with optimal tension and precise clearing of any faults in the yarn. While very similar process, there are some key differences between the winding of warp vs. weft yarn namely the size of the yarn packages.

• Clearing Yarn Faults: During rewinding, the yarn passes through an electronic yarn clearing device that detects and removes thick, thin and other defects in the yarn. When a defect is detected, the yarn clearer triggers a cutting mechanism to remove the faulty section then automatically splices the yarn to continue the winding process.
• Warp Yarn Winding: Warp yarn winding machines transfer yarn from the yarn packages onto larger cones (typically 5-10kg). During this process, the wound tension is precisely controlled. Winding machines hold 6 or more cones of yarn. As the yarn runs out from each smaller cone, modern winding machines automatically splice the yarn from the next cone, typically utilizing air splicing for nylon and polyester and thermal splicing for UHMWPE.
• Weft Yarn Winding: For nylon, polyester and UHMWPE, weft yarn is rewound from yarn packages onto cones called cheeses with pronounced tapered shapes, optimized for rapid, tangle free unwinding onto shuttleless looms. Weft yarn preparation also includes applying specialized lubricants typically by spraying it on as the yarn is wound. Weft yarn is prepared for weaving after the winding process whereas warp yarn requires a great deal more processing as detailed below.

Warp Beam Preparation

Layering yarns onto the weaver’s beam is like laying the foundation of a house before it is built, all of the yarns must be laid out precisely to allow for the fabric to emerge. The warping, sizing and drawing-in process are all foundational to prepraing the warp yarn. Conversely, preparing the weft yarn is much simpler and is completed with the previous completed winding process.

Warping

• Creeling: Large quantities of yarn cones are loaded onto a creel frame. The yarns are drawn into guides which maintain tension and alignment as the yarn is pulled off of the cone. The ends of the yarn are then attached to the warper’s beam using a variety of methods.
• Sectional Warping: This process involves winding the warp yarn section by section onto specific sections of the warper’s beam. Sectional warping is preferred when multiple types of yarn are being combined. It allows for easier implementation of reinforced areas in the fabric structure as well as better tension control. It also is preferred for frequent design changes.
• Direct Warping: For this version of warping, the weaving beam is positioned to receive all of the yarns directly from the creel at the same time. Direct warping is preferred for more efficient production of simpler, uniform fabric styles. It also is reduces risk of weak points that can occur at section boundaries in sectional warping.

Sizing

Sizing solutions enhance yarn strength and reduce friction during weaving. Sizing solutions are specific to the type of fabric, designed to work with the polymer’s properties.

• Preparing the Sizing Solution: Solutions are mixed in large vats, typically 15-20% sizing materials, 80-85% water. Beyond water, sizing solutions contain:
  1. A Base Sizing Agent
  2. Additives: Lubricants, Plasticizers, Anti- Static Agents
  3. Optional Additives: Water Repellent Agents
• Application of Sizing Solution: Sizing solution is processed as the warp yarns are passed through and immersed in the sizing solution within a sizing box. Various heating and press rollers are used to insure adequate coating of the yarns.
• Drying: The coated yarns are then passed through drying cylinders or a hot-air drying system. The water is evaporated and the sizing solution solidifies and sets on the yarn.
• Splitting: The drying warped yarns can form a sheet like structure. The coated yarns are separated at this phase to insure that they are separate yarns.
• Beaming: The sized yarn are finally rolled onto the weaver’s beam under controlled tension.

Weaving Processes & Looms

The weaving process involves the interweaving of warp and weft yarns. As the warp yarn rolls off of the beam into the loom, the weft yarn is passed back and fourth between the warp yarn in the shedding process. In this section we describe the details of this process and the loom mechanisms that support it as well as the various styles of looms.

Drawing-in

Setting up the loom for weaving is the most labor intensive part of the weaving process. Passing thousands of yarns through the drop wire, heddle and reed is very time consuming. Automated machinery has been developed to speed up the process.

• Weaver’s Beam to Back Roll: Yarns are unwound from the weaver’s beam and passed over the back roll. During weaving, the back roll is synchronized with the take-up roll and is essential in maintaining a constant level of yarn tension as well as a consistent angle of the yarn as it passes through the loom.
• Drop Wire: Yarns are passed through drop wires. These are thin wires with a small eye through which the yarn passes. During weaving, if a yarn breaks or runs out, the drop wire falls, triggering a mechanism that stops the loom.
• Heddle: Each yarn is threaded through the eye of a heddle, which is attached to one of the two heddle harnesses. Weave patterns are determined by the arrangement of heddles between the two heddle harnesses. During weaving the two heddle harnesses alternately lift and drop, creating the shed through which the weft yarn is passed.
• Reed: Yarns are passed through the reed. During weaving the reed presses the weft yarn into the shed forming the fabric through the beating-up motion.
• Take-up Roll to Cloth Roll: The drawing-in process is completed by passing the yarns over the take-up roll and securing them to the cloth roll. During weaving, as the fabric is woven, it is pulled forward onto the take-up roll. The speed of the take-up roll controls the picks per inch (the number of weft insertions in the fabric per inch). The finished fabric finally wraps up onto the cloth roll.
• Manual vs Automated: Manual drawing-in involves threading thousands of warp yarns individually through the drop wires, heddles and reed by hand. This very time-consuming process is standard for smaller-scale weaving operations. For large-scale operations, very complex drawing-in machines automatically thread the looms, significantly speeding up the process and reducing labor costs.
• Tying-in: Once a loom has been drawn-in, if the weave pattern is being maintained for the next weaver’s beam of yarn, the tying-in process dramatically speeds up the transition. Either a manual process or a tying-in machine can be used to knot or splice the ends of the initial yarns to pass through the loom to the starts of the yarns on the weaver’s beam.

Weaving

The weaving of the high-quality fabrics utilized in bike bags relies on complex, highly-technical loom setups and processes. A series of systems must each be precisely optimized for their specific role while being synchronized within the overall weaving process.

• Synchronization, Speed and Tension: Timing is everything as they say. For a loom to operate effectively and efficiently in the production of high-quality fabric, the mechanisms that control all of the processes described below must be precisely configured.
  • Synchronization is critical as every one of these processes directly and continuously feeds into the other at a very high pace. For example, dwell time, the period that the warp shed remains open, must be just enough time for the weft yarn to be inserted in the picking process and the reed to press in the weft yarn in the beating-up process.
  • The speed, acceleration and deceleration of all mechanisms must be fine tuned within the constraints of the overall loom synchronization. The motion of each mechanism must ramp up, move and slow down at a smooth, controlled pace.
  • The consistent maintenance of optimal warp and weft yarn tension throughout the entire weaving process is one of the most important outcomes of accurately controlling a loom’s synchronization and speed. Precisely controlled yarn tension is essential in the production of high-quality fabric.
• Warp Let-Off: Warp yarns, are gradually released from the warp beam at a controlled rate under precise tension.
• Shedding: During each weave cycle, one of the loom’s two heddle harnesses is raised into the up-shed position, while the other harness is dropped into the down-shed position. In this position the warp yarns are formed into a shed, through which the weft yarn is passed through in the picking process. After the weft yarn is picked and beaten-up into the fell of the fabric, the two heddle harness reverse positions, creating the next shed.
  • Shed Size and Angle: The height and depth to which the heddle harnesses lift the warp yarn and the point at which the yarns come together to form the fabric at the fell, create the shed size and angle. This size and angle are crucial for allowing the smooth passage of the weft insertion mechanism in the picking process. The geometry of this opening also is tuned to minimize the friction between warp yarns and optimize the even formation of the fabric.
• Picking: Also known as weft insertion, this is the process through which the weft yarn is propelled through the shed. This process varies tremendously depending on the picking mechanism. The various loom types are named for their picking mechanism, including shuttle looms, rapier looms and air-jet looms.
• Beating-Up: After the weft yarn is passed through the shed. it is pressed into the fell, the position where the warp yarns converge to form the fabric. The weft yarn is pressed by a mechanism called the reed, a comb like devise mounted to the loom’s sley, the mechanism that moves the reed back and fourth. The degree to which the weft yarn is pressed into the fabric is a crucial aspect of fabric density and thereby its durability, water resistance and structure.
• Fabric Take-Up: The woven fabric is rolled onto the fabric beam under precise tension and synchronization with the other loom mechanisms.
• Other Loom Processes:
  • Stop Motion: This process detects faults and broken yarns during the weaving process and automatically stops the loom. Broken warp yarns are detected when a drop wires fall. Broken weft yarn are detected by electronic tension sensors. Electronic sensors are also used to detect inconsistencies in both warp and weft yarns.
  • Yarn Joining: After the loom is stopped, the yarn must be rejoined before the loom can be restarted. A variety of processes can be used to rejoin yarn. For modern looms weaving nylon, polyester and UHWMPE air splicing or thermal splicing are the most commonly used processes. Both of these processes create smooth, strong joints in the yarns, maintaining the fabric’s uniform look and strength.
  • Selvages: The tightly woven edges on either side of the warp direction of the fabric are necessary for preventing fraying and maintaining the fabric’s structural integrity while the fabric roll is being handled and transported. Selvages are typically not incorporated into bike bag designs and are cut away during the fabric cutting phase of construction. Tucked or leno selvages are most commonly used in the weaving of nylon, polyester and UHWMPE fabrics. Tucked selvages involve tucking the weft yarn back into the edge of the fabric, while leno selvages uses two extra warp yarns that twist around and interlock with the weft yarn. Often times stronger specialized warp yarns are used for the selvages.

Loom Types

The previously described weaving processes are the standard processes across looms. Now, we’re exploring the aspects of these mechanical processes that are optimized either for their speed or for their complexity and adaptability in ways that significantly differentiate the looms.

Loom types are primarily defined by their shed mechanism and their weft insertion mechanism. We’re focused on the combinations of these two mechanisms within the looms most commonly used for weaving the nylon, polyester and UHMWPE fabrics found in bike bags. The six typical loom configurations used to weave these fabrics, range from the high-speed, basic-pattern oriented Cam/Air-Jet loom to the slower-speed, complex-pattern oriented Jacquard/Rapier loom. See our chart below for the common use of these configurations. But first, we’ll look individually at shed and weft insertion mechanisms.

• Shed Mechanisms: The pattern with which the warp yarns are simultaneously lifted and dropped in the shedding process, determines the weave pattern of the fabric. Shed mechanisms style are defined by their different systems for grouping and moving the heddles. The cam, dobby and jacquard shed mechanisms support an increasing degree of weave pattern complexity as well as the ability to easily change between patterns from one fabric roll to the next.
  • Cam: The simplest of the shed mechanisms, cams are typically used for the high-speed production of simple, repetitive weave patterns, such as plain weaves or basic twills, most typically in nylon and polyester. The cam mechanism is directly connected to the heddle harnesses, with each cam typically controlling one harness. Cam looms are best suited for fabrics requiring a small number of harnesses (usually 4-8). The simple and robust nature of cam looms makes them low maintenance and cost effective for high volume production of basic weave patterns.
  • Dobby: Ideal for weaving fabrics with moderately complex patterns and only operating slightly slower than cam looms, dobby looms are widely used for producing the moderately complex fabrics used in bike bags. During each weft insertion cycle, the dobby selects which harnesses to raise or lower, typically through an electronically programmed system. Dobby looms can typically handle patterns with up to 24 to 32 harnesses allowing for a wide range of woven patterns.
  • Jacquard: Enables the individual control of each warp thread, allowing for the creation of extremely intricate and detailed weave patterns. While typically slower and more expensive than other shedding mechanisms, jacquard looms are particularly valuable when weaving fabrics that require intricate patterns, specialized textures, variable colors or the integration of multiple functional properties within a single fabric structure. During each weft insertion cycle, the electronically programmed jacquard head individually selects which harness cord (a form of heddle particular to jacquard looms) to raise or lower the warp yarn or group of yarns.
• Weft Insertion Mechanisms: The development of the flying shuttle and then the power loom during 18th century were some of the most influential inventions in propelling the world into the industrial revolution, by automating and vastly speeding up the previously arduous manual process of weft insertion. Since that major break through, the weft insertion mechanism in looms have continued to advance with increasingly faster, more efficient and more precise methods for passing the weft yarn through the shed. In the weaving of the fabrics used in bike bags, air-jet and rapier are by far the most common weft insertion methods. Other methods such as water-jet and projectile are utilized occasionally as well.
  • Air-jet: Uses a jet of compressed air to propel the weft yarn through the shed at very high speeds (up to 1500 picks per minute). A main nozzle launches each weft yarn with relay air-jet nozzle guiding the yarn through the shed. The weft yarns used in air-jet looms need to be smooth, strong, and relatively lightweight to withstand the force of the air jet, making nylon and polyester particularly well-suited. UHMWPE, while more challenging to weave with air-jet looms due to its low-density and high-strength properties, can be optimized for this high-speed production method using specialized air-jet settings.
  • Rapier: Uses a thin rod to carry the weft yarn through the shed or two rods where the yarn is transferred at the center from one rod to the other (double rapier). Rapier looms offer a balance of precise control for more complex weave patterns, sufficient speeds (up to 700 picks per minute) and adaptability to delicate or high-strength yarn such as UHMWPE, multifilament, monofilament and textured. Their precision control includes the ability to more easily be setup for multiple types of weft yarn. Used in combination with dobby and jaquard shed mechanisms, the overall higher mechanical complexity requires higher maintenance as compared to the simpler air-jet loom setups.

Shed Mechanism	Air-jet (High-Speed)	Rapier (Adaptability)
Cam (Basic Patterns)	●	◯
Dobby (Moderate Patterns)	●	●
Jacquard (Complex Patterns)	◯	●

Legend:
● = Common
◯ = Less Common

Weave Patterns

Weave patterns result from varying the pattern with which warp and weft yarns interlace with one another. The simplest pattern is the plain weave, where each weft yarn passes over then under each successive warp yarn, alternating this pattern with the next weft yarn. This creates a simple checkerboard effect and serves as the foundation from which other weave patterns are derived.

Amongst the broad array of weave patterns beyond the plain weave, it is important to note that there are often overlaps where the variants of two differently named weave patterns are actually the identical weave pattern. The nomenclature used to define weave patterns is often an identification of the weave structure combined with fabric’s overall properties and intended uses. Consider the example of a 2×2 basket weave and a 2×2 oxford weave. While pattern wise these are essentially identical, the terminology used to contrast these two fabrics has to do with the comparing the end products which despite having the same weave pattern may differ substantially for a whole of other design factors. The confusion between overlapping weave patterns underscores the importance of considering a fabric’s overall properties rather than just the weave pattern itself.

• Pattern Fundamentals: Weave patterns emerge through four main variation to the pathway of the weft yarn, through the creation of floats. A float is anytime a warp or weft yarn passes over or under multiple opposing weft or warp yarns. Every weave pattern other than the plain weave contains floats. The patterned arrangement of floats is essential to what weave patterns are.
  • The weft yarn can pass over two or more warp yarns before passing under the next, creating weft floats.
  • One or more subsequent weft yarns can repeat the path through the warp yarns, rather than alternating, creating warp floats.
  • OR the next weft yarn can take the path opposite to its previous path, creating alternating weft floats.
  • OR the next weft yarn can take a completely different path over and under the warp yarns, potentially creating unique weft and warp floats and resulting in more intricate designs, like satin or Jacquard weaves.
• Plain Weave: The plain weave is simply the alternate passing of the weft yarn through the warp, creating a checkerboard pattern across the fabric. As simple as it gets, the plain weave is also the most commonly used weave amongst the fabrics found on bicycle bags.
• Ripstop Weave: A variation of the plain weave, the ripstop weave uses thicker, stronger yarns interwoven at regular intervals in both the weft and warp directions to create a grid like pattern which reinforces the fabric and inhibits tears from spreading. The ripstop style comes in many variations, from the classic grid pattern to mini grids to diamond or honeycomb patterns. Other variants can include using all imaginable styles of reinforcement yarn and more complex blends of ripstop patterns as well as integrations with other weave patterns. Many variations of ripstop fabrics are commonly found throughout bike bags and are appreciated for both their light-weight strength and visual appeal.
• Twill Weave: Characterized by its diagonal pattern, the twill weave typically involves the weft yarn passing over two warp yarns and then under one warp yarn (in a 2/1 twill). Each successive weft yarn follows the same over-two, under-one pattern, but shifted one warp yarn to the side, creating the characteristic diagonal lines. This pattern varies in angle and prominence depending on the specific twill variation used. Common variants include 2/1 twill, 2/2 twill, and 3/1 twill. Twill weaves are known for their strength and durability. Their staggered yarns create a denser fabric that is more resistant to tearing and abrasion. Compared to plain weave, twill fabrics are more flexible with better drape, allowing them to conform to a variety of shapes.
• Basket Weave: Yet another variation to the plain weave, the basket weave could be summarized as the plain weave plus. Where the plain weave has single weft and warp yarns interweaving with each other, the basket weave has two or more yarns following the same pattern. Common variants of the basket weave includes 2×2, 3×3, or 4×4 basket weaves. Basket weaves are known for their increased texture, which adds to their visual interest and grip. They also offer more flexibility and softness, better drape, increased air permeability and increased abrasion resistance. Basket weaves are often utilized in outer facing applications on bike bags.
• Weaves Less Commonly Found in Bike Bag Fabrics:
  • Oxford Weave: A variant of the basket weave, the oxford weave typically involves a single weft yarn passing over and under pairs of warp yarns, creating a fabric with similar characteristics to the basket weave. In fact, the 2×2 oxford weave and 2×2 basket weave are essentially the same weave pattern. Its textured, slightly rough surface is a defining characteristics of the oxford weave which often incorporates a heavier, double yarn in the warp direction and a lighter yarn in the weft.
  • Satin Weave: Typically used only in the liners and for decorative flares in bike bags, the satin weave is characterized by a smooth, lustrous surface achieved typically by floating the weft yarn over multiple warp yarns before interlacing. This results in fewer intersections between the yarns, creating a sleek, shiny fabric with a softer feel. While it can offer good water repellency due to smooth surface, it typically is only used in liners on bike bags due to its lower durability and potential snagging. Typical variants include 4×1, 5×1 and 8×1 and many other variants abound.
  • Leno Weave: In this specialized weaving technique, pairs of warp yarns are twisted around each other using specialized doup heddles which turn back and fourth to twist each pair of warp yarns after each weft pass. This twist creates an open, mesh-like fabric that is lightweight yet stable and resists fraying due to the interlocking of the yarns. The breathable nature of this weave makes it excellent for external pockets for holding wet items as well as lightweight internal pockets and dividers.
• Weave Pattern’s Structural Impact: Beyond dramatically effecting a fabric’s visual appearance, weave patterns impact the structural properties of the fabric. A fabric’s structure is of course the combined effect of the weave pattern and the yarn’s structure. Practically speaking, understanding fabric structure is generally much more of an art than a precise science. Scientific principals can be applied in improving our understanding of the structural properties of various weave patterns, however comprehensive studies and data that fully models out specific fabric’s structural properties are generally unavailable. Please see our fabric structure property for the basic principles of how weave patterns effect the fabric’s structure.
• Fabric Construction Variants: The following techniques involve broader structural changes or combinations of materials, without changing the fundamental weave pattern. These methods can be applied to any weave pattern to enhance characteristics like strength, durability, insulation, or functionality.
  • High-Density: This weave variant involves increasing the number of warp and weft yarns to achieve increased density. Increased density enhances fabric properties including durability, water resistance and UV resistance. Specialized looms with finer, more closely spaced shedding mechanisms are required for accommodating the typically finer yarns. The tightly packed together nature of the fabric results in a smoother fabric enhanced with water and wind resistance. This weaving technique is very commonly applied to nylon and polyester fabrics. Less common in UHWMPE due to extra high costs, it is non-the-less used for very high-performance applications.
  • Multiple Yarn Types: In this technique different types of yarn are combined within any of the above weave types to enhance the fabric’s overall performance. The unique properties of each of the yarn types is leveraged to its maximum benefit and to work synergistically together. Different yarns can be used in specific areas of the fabric to provide targeted performance, such as reinforcing high-stress zones with stronger yarns while keeping other areas lightweight and flexible. Yarn types can be combined to meet specific needs, such as increased abrasion resistance, improved moisture management, or reduced weight.
    • Nylon + UHMWPE:
      • Combines nylon’s flexibility with UHMWPE’s strength
      • Used in high-wear areas
    • Polyester + Nylon:
      • Blends polyester’s UV resistance with nylon’s strength
      • Common in all-weather bike bags
    • UHMWPE + Polyester:
      • Pairs UHMWPE’s strength with polyester’s affordability and UV resistance
      • Used in high-performance, durable fabrics
      • Adds stretch to fabrics for flexible pockets or adaptable bag designs
    • Nylon or Polyester + Elastane:
      • Adds stretch to fabrics for flexible pockets or adaptable bag designs
  • Multi-Layer: AKA double weave or multi-ply, this weave variant involves weaving two or three layers of fabric simultaneously during the same weaving process. Requiring specialized looms that support separate warp and weft yarn systems, multi-layer fabrics are much more complex to weave than single-layer fabrics. Fabrics woven with this technique are distinct from laminated or bonded multi-layer fabrics in that they are essentially a single fabric woven all-at-once with multiple interconnected layers. Typically consisting of two or three distinct fabric layers, manufacturers can utilize any variety of weaves to strategically select and combine weave patterns, engineering fabrics that offer custom functionality, superior strength, flexibility, abrasion resistance, and other desirable properties. Multi-layer fabrics are commonly woven with nylon, polyester and nylon/polyester blends, however they are rarely woven with UHMWPE yarn.
    Applications in bike bags can include:
    • Reinforced Panels: Enhanced durability, abrasion and water resistance in high-wear areas of bags.
    • Structural Support: Built-in shapes, inherent thickness, stiffness and structural integrity without additional layers or inserts.
    • Padded Straps or Back Panels: Woven-in cushioning can include variable thickness to optimize for design.
    • Built-In Compartments: Pockets or compartments are woven directly within the fabric itself. Layers are connected or separated during weaving to form openings or enclosed spaces.
    • Ventilated Areas: Provides structure and protection while allowing for air circulation.
    • Insulated Sections: Layers incorporate insulating materials woven into the fabric for thermal protection.

Fabric Measurements

Now that we’ve considered the full process of how fabrics are manufactured and peered into all of the weave patterns that are produced, we are summarizing the various ways that fabrics are measured. Understanding the nomenclature used in fabric measurement can be very confusing for the uninitiated with a variety of overlapping and sometimes illogical terms (see thread count). We’ve written this section to organize and compare all of these terms in as digestible a way as possible.

Also, see the end of our yarn guide for related in-depth overview of yarn related measurements.

Density & Mass Fabric Measurements

Measurements relating to the density and mass of fabric are crucial indicators of a fabric’s physical properties. Understanding fabric density and mass enables bike bag manufacturers to optimize material selection for specific applications, balancing factors like durability, weather resistance, and overall bag weight.

Thread Count

Thread count is the total number of warp and weft yarns in a specified area of fabric, usually measured per square inch (in²) or per 10 centimeters (cm) square in metric systems. Thread count is a crucial measurement in fabric construction as an indicator of the density of the fabric.
***Thread count is an especially confusing term in that we are counting yarns not threads. It would make much more sense if it were called yarn count, however tradition and market inertia prevail.

• Units of Measure:
  • Threads Per Inch (TPI): The total number of warp and weft yarns counted within one square inch of fabric. This is the most common unit used in the United States.
  • Ends Per Inch (EPI): The number of warp yarns (ends) in one inch of fabric length.
  • Picks Per Inch (PPI): The number of weft yarns (picks) in one inch of fabric width.
  • EPI × PPI: This format provides a clear understanding of the fabric’s construction density in both warp and weft directions.
  • Threads Per Centimeter (Threads/cm): In metric systems, thread count may be measured per square centimeter. For higher precision, counts per 10 square centimeters are used.
    ***In metric systems, Ends Per Centimeter (EPC) and Picks Per Centimeter (PPC) as well as EPC x PPC are utilized for detail of warp vs. weft yarn count.
• Example Fabrics with Approximate Thread Counts:
  • 500D Cordura® Nylon Fabric – 48 EPI × 38 PPI
  • 600D Polyester Fabric – 60 EPI × 40 PPI
  • 70D Ripstop Nylon Fabric – 104 EPI × 104 PPI
  • 1680D Ballistic Nylon Fabric – 34 EPI × 34 PPI
• Fabric Properties Indicated by Thread Count:
  Thread count is an important indicator of various key fabric properties. While thread count alone generally does not determine these fabric properties, thread count in combination with yarn material, yarn denier and weave pattern influence these properties.
  • Durability: Higher thread counts generally contribute to higher durability. Abrasion, tear and puncture resistance all can be a positive benefit of denser tighter weave. A higher strength to weight ratio if often a result of increasing thread count.
  • Water Resistance: Higher thread counts typically result in better natural water resistance as tighter weaves leave less space for water to penetrate.
  • Structure: High thread counts can make fabrics stiffer, affecting how the bag conforms to its contents or how it can be packed. Higher thread counts can also produce a smoother fabric texture, which may be preferred for aesthetic reasons or to prevent snagging.
• Thread Count’s Interconnection with Other Measurements:
  (The following comparison summaries are based on scenarios where only the listed measurement is altered and ALL other factors remain equal.)
  • to Fabric Density = Strong, Direct Correlation
    This is a highly correlated relationship. Higher thread count leads to a denser fabric, as the tightness of the weave (thread count) determines how closely yarns are packed, influencing the mass per unit volume. In fact thread count is often considered to be an approximate measurement of fabric density.
  • to Denier = Strong, Inverse Correlation
    This is an inverse relationship. Higher denier yarns correlates to a lower thread count fabric.
  • to Fabric Weight = Strong, Direct Correlation
    Heavier fabric correlates with a higher thread count though the relationship is not proportional.
  • to Fabric Thickness = Moderate, Direct Correlation
    Thicker fabric typically correlates with a higher thread count due to the increased number of yarns occupying space within the fabric.

Fabric Weight

Fabric weight is the measure of the mass of the fabric per unit area, indicating how heavy or light a fabric is. This is a crucial measurement for determining the fabric’s suitability for specific applications, affecting durability and performance.

• Units of Measure:
  • Ounces per Square Yard (oz/yd²): Commonly used in the United States, indicating the weight in ounces of one square yard of fabric.
  • Grams per Square Meter (GSM): The most common unit internationally, indicating the weight in grams of one square meter of fabric.
  • Conversion: 1 oz/yd² ≈ 33.91 g/m²
• Example Fabrics with Approximate Fabric Weight:
  • 500D Cordura® Nylon Fabric – 6.5 oz/yd² (220 GSM)
  • 600D Polyester Fabric – 7.1 oz/yd² (240 GSM)
  • 1000D Nylon Fabric – 10.3 oz/yd² (350 GSM)
  • 70D Ripstop Nylon Fabric – 2.1 oz/yd² (70 GSM)
• Fabric Properties Indicated by Fabric Weight:
  • Durability: Heavier fabrics tend to be more durable and resistant to abrasion, making them suitable for heavy-duty applications. Often correlating with higher tensile strength and load-bearing capacity, heavier fabrics can offer better protection against punctures, impacts, and environmental factors.
  • Structure: Lighter fabrics tend to be more flexible and easier to handle, while their heavier counterparts may be more rigid.
  • Weight: As it says in the name of the measurement, lighter weight fabrics will help reduce the overall weight of the bike bag.
• Fabric Weight’s Interconnection with Other Measurements:
  (The following comparison summaries are based on scenarios where only the listed measurement is altered and ALL other factors remain equal.)
  • to Denier = Strong, Direct Correlation
    Higher denier yarns correlates to a higher fabric weight.
  • to Fabric Density = Strong, Direct Correlation
    Higher fabric density correlates to a higher fabric weight.
  • to Thread Count = Strong, Direct Correlation
    Higher thread count correlates to a higher fabric weight.
  • to Fabric Thickness = Strong, Direct Correlation
    Higher fabric thickness correlates with a higher fabric weight.
  • to Fabric Ply = Strong, Direct Correlation
    Multi-ply versions of a fabric will increase weight proportionately with each additional ply.
  • to Multi-Ply Yarn = Strong, Direct Correlation
    Fabric made with multi-ply yarn will increase weight proportionately with each additional yarn ply which effectively multiplies the yarn’s denier.

Fabric Thickness

The distance between the top and bottom surfaces of a fabric.

• Units of Measure:
  • Millimeters (mm)
  • Inches (in)
• Example Fabrics with Fabric Thickness:
  • 500D Cordura® Nylon Fabric – 0.5 mm thick
  • 1000D Nylon Fabric – 0.75 mm thick
  • 70D Ripstop Nylon Fabric – 0.1 mm thick
• Fabric Properties Indicated by Fabric Thickness:
  • Durability: Thicker fabrics tend to be more durable and resistant to abrasion as compared to their thinner counterparts.
  • Structure: Thinner fabrics tend to be more flexible and easier to handle, while their thicker counterparts may be more rigid and bulkier.
• Fabric Thickness’s Interconnection with Other Measurements:
  (The following comparison summaries are based on scenarios where only the listed measurement is altered and ALL other factors remain equal.)
  • to Denier = Strong, Direct Correlation
    Higher denier yarns correlates to a higher fabric thickness. Using higher denier yarns increases the overall fabric thickness because thicker yarns occupy more vertical space in the fabric.
  • to Multi-Ply Yarn = Strong, Direct Correlation
    Like denier multi-ply yarn typically correlates to a thicker fabric with each additional yarn ply effectively multiplying the yarn’s denier.
  • to Fabric Ply = Strong, Direct Correlation
    Multi-ply versions of a fabric will increase fabric thickness proportionately with each additional ply.
  • to Thread Count = Moderate, Direct Correlation
    Higher thread count typically correlates to a thicker fabric. With more threads interwoven, the fabric can become thicker as the yarns may overlap or compress vertically.
  • to Fabric Weight = Moderate, Direct Correlation
    Higher fabric weight typically correlates with a thicker fabric though the relationship is not always proportional.
  • to Fabric Density = Moderate, Inverse Correlation
    For a given fabric weight, increasing thickness decreases fabric density.

Fabric Density

Dividing the weight of a fabric by its thickness yields its mass per unit volume, known as its density. This measurement indicates how closely the yarns are packed together within the fabric structure and is a crucial measurement for understanding the compactness and firmness of a fabric.

• Units of Measure:
  • Grams per Cubic Centimeter (g/cm³)
  • Kilograms per Cubic Meter (kg/m³)
  • Fabric Density = Fabric Weight (GSM)​ / Fabric Thickness (mm)
• Example Fabrics with their Fabric Density:
  • 500D Cordura® Nylon Fabric
    • 220 GSM / 0.5 mm = 0.44 g/cm³
  • 1000D Nylon Fabric
    • 350 GSM / 0.75 mm = 0.47 g/cm³
  • 70D Ripstop Nylon Fabric
    • 70 GSM / 0.1 mm = 0.70 g/cm³
• Fabric Properties Indicated by Fabric Density:
  • Durability: Higher fabric densities generally contribute to higher durability. A denser fabric has yarns packed more tightly, enhancing abrasion, tear, and puncture resistance.
  • Water Resistance: Denser fabrics typically exhibit better natural water resistance, as tightly packed yarns leave less space for water to penetrate.
  • Structure: High fabric density can make fabrics stiffer, affecting how a bag conforms to its contents or how it can be packed. Denser fabrics may also have less stretch and more dimensional stability.
• Fabric Density’s Interconnection with Other Measurements:
  (The following comparison summaries are based on scenarios where only the listed measurement is altered and ALL other factors remain equal.)
  • to Thread Count = Strong, Direct Correlation
    Higher thread count correlates to a higher fabric density, meaning more yarns are packed into a given area, increasing the mass per unit volume of the fabric.
  • to Denier = Strong, Direct Correlation
    Higher denier yarns correlates to a higher fabric density, however the relationship can be complex as denier affect both mass and volume components of density.
  • to Multi-Ply Yarn = Strong, Direct Correlation
    Like denier multi-ply yarn typically correlates to a higher fabric density with each additional yarn ply effectively multiplying the yarn’s denier.
  • to Fabric Thickness = Strong, Inverse Correlation
    Higher fabric thickness inversely correlates with a higher fabric density.
  • to Fabric Weight = Strong, Direct Correlation
    Higher fabric weight typically correlates with a higher fabric density though the relationship is not always proportional.

Fabric Ply

Fabric ply refers to the number of distinct layers in a fabric that are woven, bonded or laminated together to create a single, unified fabric structure. Each layer, or ply, can serve a specific function, and combining them allows manufacturers to create fabrics with tailored properties to meet specific needs.
***Fabric ply is distinct from yarn ply, which refers to the number of strands twisted together to form a single yarn.

• Units of Measure:
  • Number of Plies: 1-ply, 2-ply, 3-ply, etc.
    (Also referred to as single-ply, double-ply and multi-ply.)
• Example Fabrics with their Fabric Ply:
  • 2-Ply Ripstop Polyester Fabric
  • 3-Ply UHMWPE Composite Fabric
  • 2-Ply Laminated Nylon Fabric
• Fabric Properties Indicated by Fabric Ply:
  Fabric ply can indicate a broad variety of fabric properties because of the properties influenced by the combination of the multiple layers as well as the fact that each individual layer can be differentiated for specific properties.
• Fabric Ply’s Interconnection with Other Measurements:
  Fabric ply has relatively straightforward relationships with most measurements because it acts more as a multiplier of existing properties rather than creating complex interactions.
  (The following comparison summaries are based on scenarios where only the listed measurement is altered and ALL other factors remain equal.)
  • to Fabric Thickness = Strong, Direct Correlation
    Higher fabric thickness correlates with more fabric plys.
  • to Fabric Weight = Strong, Direct Correlation
    Higher fabric weight correlates with more fabric ply.

Dimensional Fabric Measurements

Measurements relating to the length, width and area of fabric are fundamental standards in fabric manufacturing. These measurements are also crucial for optimizing fabric usage when manufacturing bike bags.

Linear Meter or Yard

The measurement of the the length of fabric measured along its lengthwise direction.

• Units of Measure:
  • Linear Meter (m): The standard unit for fabric length in most countries.
  • Linear Yard (yd): Commonly used in the United States.
• Applications:
  • Calculating the total length of fabric required for manufacturing bags, accounting for all components and pattern pieces.
  • Fabrics are often sold by the linear meter or yard. This measurement helps determine how much fabric is needed for a project.
• Related Measurements:
  • Cut Length: Fabric sold in specific lengths as requested, rather than in full rolls, allowing bag designers, small scale and custom manufacturers as well as DIYers to buy only the amount needed, minimizing excess inventory.
  • Roll Length: The total length of fabric wound onto a roll. This is important for inventory management and planning production batches.

Usable Width

The width of the fabric that can be utilized in production, excluding selvedges and any non-functional edges.

• Units of Measure:
  • Centimeters (cm): The standard unit for fabric width in most countries.
  • Inches (in): Commonly used in the United States.
• Applications:
  • Critical for accurate material estimation and pattern layout.
  • Ensures that pattern pieces are only placed within the usable area to avoid defects and maintain quality.
• Related Measurements:
  • Full Width: The total width of the fabric that can be utilized in production, from one selvedges to the other. This is important for Important for understanding the maximum possible width of pattern pieces.
  • Selvage Width: The width of the non-functional edges on both sides of the fabric.

Square Meter or Yard

The measurement of the fabric’s area calculated by multiplying the usable width by the length.

• Units of Measure:
  • Square Meter (m²): The international standard for measuring a fabric’s area.
  • Square Yard (yd²): Commonly used in the United States.
• Applications:
  • Used for pricing, costing, and inventory management when fabrics are sold or purchased by area.
  • Essential for calculating the total fabric area needed for a production run.
• Related Measurements:
  • Fabric Consumption: The total area of fabric required to produce one unit of a product, including allowances for seams, hems, and waste.
  • Marker Efficiency: The percentage of fabric area that is utilized by the pattern pieces in a marker layout. Optimizing marker efficiency reduces material costs and environmental impact.
  • Pattern Dimensions: The area, length and width of each pattern piece that will be cut from the fabric. Determines how patterns are arranged on the fabric (marker making) to minimize waste.
    ***Also related to Usable Width and Linear measurements.