This blog post is another pictorial “recipe” for creating or retrofitting frame bags that are very stable and can carry more gear. The pictured bag has a capacity of more than 15 litres, and is loaded with water and gear. The key to maximizing the stable usable volume are internal composite stiffening panels fastened to portions inside the sides, back, and top of the fabric bag. If you’re retrofitting an existing bag just cut it down the centre line and then add a width strip to your needs (including Velcro OneWrap daisy chains), and the internal panels. This project took about 20 hours to complete. The materials and design are intended to accessible to folks. Several thousand hours of prototyping and field-testing have been incorporated into this design. While this implementation is ultra-light and not inexpensive, you can get creative with found and upcycled materials.Avoid using coiled zippers if you want to create a durable and high-performing project.
Overview: 14 litres of water in three bladders, plus the other gear pictured below. The left side internal composite panel is visible in the lower triangle of the bag. The perimeter of the bag is attached to the frame with Velcro and a few zip ties. This bag is made from Challenge Sailcloth Ultra 200 and weighs about 300 grams. All seams are taped with Challenge Sailcloth Ultra TNT. The combination of the materials and rain cover on the zipper create a highly water resistant bag. Ultra 200 is a UHMWPE fabric (Ultra High Molecular Weight Polyethylene), and is extremely strong and durable.
The spare fatbike tube (white rectangle, top right) sits in the bottom of the bag. The three bladders are then stacked in the frame bag, with the remaining gear sitting on top. An MSR hydration hose can be attached to any of the bladders and routed out through a front or back port.
Both upper and lower zipper tracks are stiffened to maintain tooth alignment. YKK #5 Vislon zippers represent a durable yet lightweight choice. Coil zippers will fail prematurely.Top view with the bag loaded and the zipper closedDrive side view. I prefer the zipper on the left side for ease of access while riding, and when the bike is stored in my tent vestibule.Some of design elements become visible. The width has been optimized for Q factor and pedaling clearances. The combination of the external fabric and internal composite panels securely hold the contents from vertical and lateral movement.
Two DIY frame bags for #19, a 29’er hardtail. The bag on the left was constructed in January 2024 and incorporates all the design details outlined below. The bag on the right was built in early-2020 without the benefit of using internal composite stiffening panels and elements. The Velcro OneWrap daisy chain on each bag is used to directly secure the bag onto the centre-line of the frame. The bag on the right has many thousands of kilometers of backcountry usage.
Two of the industrial Hook Velcro VHB backed mounting patches on the frame. The lower downtube patch is ~3/4″ wide to match the exposed Loop OneWrap on the frame bag. A typical frame mounting system consists of seven to ten 3/4″ x 2″ Hook Velcro pads aligned to the centre-line of the frame. I cut these from a roll, Velcro Part #90197. A few zip ties are added at key locations to tension the bag in the frame and eliminate any movement. The dropper post cable gets routed immediately behind and below the installed frame bag.
Checking crank and drive clearances on the completed fat bike bag.
Overall construction steps: This design of framebag is based on a single cardboard template that has been carefully shaped to completely fill the main triangle of a bicycle frame. Seam allowances are added to the edges of all panels. All of the perimeter panels are measured based on the four sides of the cardboard template, plus seam allowances. The cardboard template will also be used to size the two composite stiffeners for the side panels.
Left side of frameRight (drive side) of frame. The seam allowance on all sides adds 3/4″ to each edge of the panel. You may be able to reduce this to 1/2″.A single piece of cardboard serves as the cutting template for the side panels. Adjusting your layout of all the panels will help minimize waste. In this example, another framebag was made for a different bike with the two pieces of triangular “waste”. Overall waste was very minimal.
Velcro OneWrap bar tacked to three edges enables secure mounting to the frame.The bottom of the framebag has a loop Velcro panel that matches with a hook Velcro panel on the Pinion bridge of the frame. This panel may not be needed with a conventional bottom bracket.This width of bag (~5.5″) works flawlessly for my “zero-contact” riding needs on the fat bike. The left image shows all of the main panels cut and assembly started. All edge panels are the same width to aid in precise control of the final shape of the bag.Bottom seam in the zipper cover formed from a strip of Ultra 200. A composite stiffener [aka string trimmer line 🙂 ] will be inserted into this resulting pocket.Adding a second seam to the upper zipper track. This creates another pocket near the back edge of the zipper. A second composite stiffener will be inserted into this pocket.Adding another seam to the lower zipper track. This forms a pocket for insertion of a third composite stiffener. The zipper cover is formed by a folded strip with the upper zipper track sewn to only one side of the fold.Sewing the zipper into the left panel. It is CRITICAL that the left and right side panels are exactly the same size and shape (mirror images). I typically make the zipper side panel slightly larger and then trim it to perfectly match the other side, and double check the cardboard template. This ensures that the completed bag has no twists or deformation when mounted in the frame.OneWrap bar tacked with 2″ spacing. The front end of the panel has Velcro attached to create a closable port for cables or hoses. Reverse side of the same panel with the TNT tape applied with a silicone pressure roller. I prefer to allow 24 hours for the TNT tape to cure in place before sewing the bag together.Detail of outside and inside of one of the larger perimeter panels.Joining the zipper (left) side panel to the perimeter panels.Adding the drive side (right) panel.Using a zipper foot to complete one of the closing seams.Using a standard foot to bar tack all of the corners. These joints will be sealed with TNT tape later in the process.Sewing details…keeping everything aligned and symmetrical.Using a commercial grade of line helps ensure sustained performance of the bag. Look for items that have rated performance (cycles, temperature) on the packaging.Warming the line ends with a lighter to create a smoother element.Adding 0.095″ string trimmer line to the three pockets in the zipper and rain cover. In this example Husqvarna line gets the nod. Half of the width of tape is applied to one side and then carefully folded over onto the matching face.Nearing completion of the TNT tape application and pressure rolling.Adding TNT tape to all edge and zipper seams.Lower left side panel. The height of the panel is determined by pedal sweep plus an allowance forward of the pedals. If unsure, start with a larger panel and trim it down, if appropriate.The raw weight of the four panels, prior to the addition of stiffeners, edge tape, and VHB mounting tape. The bag and all panels must be test fitted on the bike frame prior to proceeding further. The length of the shortest (top) panel is personal preference. I’m looking to have the frame bag “play nicely” with my custom large StraddleBags.Cutting and shaping the corroplast panels.Adding VHB tape to the top (left) and back (right) panels. The back panel is sized to keep that plane of the bag in tension. Once installed with the Velcro attachment system and zip ties the competed bag is extremely stable.Inserting two lengths of string trimmer line into top edge of each side panel. These help eliminate any bulging in a sides of the bag. An internal tensioning system can also be added.Preparing the panels for applicationWhile not easy to see, the side panels have 2″ Outdoor Repair tape applied to the top edges and the inside of the fabric. TNT tape also works in this application. Adding side panels. Tools and spares with 36″ of OneWrap sitting directly on top of the Pinion bridge of the bike frame.MSR Reactor stove placed onto the items at left.Test fitting some of my typical gear. A high volume mini floor pump is in the back drive side corner.The stiffening system is just visible in the zipper tracks and cover. The cover is being held open with my left hand while taking this picture. Normal position of the zipper cover. Zip ties are just visible at the junction of the top and seat tubes. There are adjacent Velcro patches on both tubes.Zipper and mounting detailsThe dropper post cable has been routed behind and below the bag. The heads of the zip ties in the top rear corner are again just visible. The edges of the upper and lower Velcro patches on the frame are visible as a line on the frame tube.Completed bag loaded with about 17 kg of gear. A zipper pull has been added to ease opening and closing, particularly while riding.
This is one of those real-world trail images that highlights this frame bag design and construction. I’d packed the bike up at about -20C after a winter overnighter. The framebag holds all water, food, stove & fuel, spare parts and belt, and some quick access outer layers. Perhaps about 15 kg of contents loosely dumped into the bag. Despite this lack of packing there’s no sag from all this weight and lack of organization.
After several thousand kilometers of Fall, Winter, and early-Spring fatbiking I’m really happy with this design and construction. At risk of over stating things …. this bag has FUNDAMENTALLY altered my bike-packing practices. Food, water, stove, fuel, tools, spares, etc. all have a stable and secure space inside ALL dimensions of a bicycle frame. The handling of the bike has noticeably improved with the overall lowered centre of gravity. The rear prototype CompressionPanniers and Sara’s new Bikepackers Foundry HandlebarBag+ (size Large) and a pair of custom StraddleBags (size Large) yield a solid expedition luggage system.
