Technology – Firefly Bicycles

Tube butting, the process of changing a tube’s wall thickness along its length, has long been held as one indicator of a top-of-the-line titanium frame. It makes frames lighter, stronger, improves ride quality, and is a key tool used to tune the tubeset to the specific rider’s needs.

The easiest and most common way to build a frame with butted tubing is to buy pre-butted tubing and pull specific tubes for specific bikes. But easy isn’t that fun, is it?

After over a year of tooling development, we now externally butt each main triangle tube in house, custom for each rider, each frame, and each tube, and all as a standard feature on our frames. That gives us unprecedented control over the profiles of our tubing. We can make the tubing fractions of an inch thicker around the joints and welded water bottle bosses, for example, while reducing the wall thickness to as low as .026” along the rest of the tubing.

Combined with custom diameter tubing, in-house butting gives us complete control over the ride quality of every frame we make.

We have spent countless hours designing and refining our dropouts to be as mechanically sound as they are beautiful. Well-designed dropouts make our bikes more efficient, more durable, compatible with all modern components, and improve shifting quality and handling.

There’s no better example of that dedication than our flat-mount disc brake dropouts. As the industry settled on flat-mount disc brakes, we spent almost a year designing what became a nearly perfect CNC-machined dropout design. Its only flaw was that the complicated multi-step welding process led to some inconsistencies in production timing. With just that small window for improvement available, and newly able to use 3D printing technology thanks to our experience with our chainstay yoke, we set out to refine and improve our dropout design yet again.

The result is our state-of-the-art, 6/4 titanium, 3D-printed flat-mount dropout design. Printed literally from the ground up, they are designed with the ideal shapes to make production timing more predictable, and to be lighter and stiffer than our previous design, all while retaining our signature Firefly aesthetic. We also offer them in six unique size combinations, including options SRAM UDH compatibility, so that the dropouts now pair perfectly with the full range of chain stay and seat stay diameters, a key to our ability to tune the ride of every bike perfectly to each rider.

We have applied that same level of attention and thoughtfulness to each of our dropout designs, and you will see it as clearly as you can feel it in the ride.

We have spent countless hours designing and refining our dropouts to be as mechanically sound as they are beautiful. Well-designed dropouts make our bikes more efficient, more durable, compatible with all modern components, and improve shifting quality and handling.

There’s no better example of that dedication than our flat-mount disc brake dropouts. As the industry settled on flat-mount disc brakes, we spent almost a year designing what became a nearly perfect CNC-machined dropout design. Its only flaw was that the complicated multi-step welding process led to some inconsistencies in production timing. With just that small window for improvement available, and newly able to use 3D printing technology thanks to our experience with our chainstay yoke, we set out to refine and improve our dropout design yet again.

The result is our state-of-the-art, 6/4 titanium, 3D-printed flat-mount dropout design. Printed literally from the ground up, they are designed with the ideal shapes to make production timing more predictable, and to be lighter and stiffer than our previous design, all while retaining our signature Firefly aesthetic. We also offer them in six unique size combinations, including options SRAM UDH compatibility, so that the dropouts now pair perfectly with the full range of chain stay and seat stay diameters, a key to our ability to tune the ride of every bike perfectly to each rider.

We have applied that same level of attention and thoughtfulness to each of our dropout designs, and you will see it as clearly as you can feel it in the ride.

Few people understand the many intricacies of welding bicycles better than our head welder, Tyler Evans, who has been welding top of the line custom titanium frames for over twenty years.

We TIG (Tungsten Inert Gas) weld our frames, stems, and seatposts, an intimate and complicated technique that gives us more control than any other form of welding. Before we even begin, we check that all of the materials are completely clean, the alloys of the tubing and the filler rod are correct, the argon is flowing out of the torch at the correct volume, and the welding machine is set up properly.

Welding is a delicate dance between the hands, eyes, and feet: one hand holds the torch, the other hand holds the filler rod, and one foot operates a pedal to control the electricity expelled from the torch. All at once we manage the amperage being used to create the puddle (heat), the speed at which the torch moves the puddle across the joint (speed), and how much filler rod is being fed into the puddle (feed). If any one of these details is off, the frame can be twisted out of alignment or structurally unsound.

That’s why we take welding so seriously and value Tyler’s industry-renowned skill so completely. Our reputation rides on every bike we make.

Two qualities distinguish our custom finishes. First is our focus on truly custom design. Anything from a graphic you create to something much less specific, like maybe a snakeskin you saw on a weekend adventure (true story) can inspire us. Whatever the source of inspiration, every custom finish is born from conversations about you, what you like, and how we can translate that into your dream Firefly.

Second is our focus on raw titanium finishes. While we do offer paint, our focus has always been titanium finishes that stay true to the material, including brushed, bead blasted, polished, and our signature anodization.

The anodized colors are illusions of refraction, like oil on water, created by microns-thin layers of clear oxide on the surface of the titanium. We create those layers by applying electricity to the frame through a saltwater solution. By controlling the voltage, we control the thickness of the oxide and therefore the color.

These techniques, plus precise masking, countless hours of experimentation, and a few other secret tricks, give us an unmatched ability to create unique and personal but timeless finishes that are lighter and more durable than paint or decals.

Two qualities distinguish our custom finishes. First is our focus on truly custom design. Anything from a graphic you create to something much less specific, like maybe a snakeskin you saw on a weekend adventure (true story) can inspire us. Whatever the source of inspiration, every custom finish is born from conversations about you, what you like, and how we can translate that into your dream Firefly.

Second is our focus on raw titanium finishes. While we do offer paint, our focus has always been titanium finishes that stay true to the material, including brushed, bead blasted, polished, and our signature anodization.

The anodized colors are illusions of refraction, like oil on water, created by microns-thin layers of clear oxide on the surface of the titanium. We create those layers by applying electricity to the frame through a saltwater solution. By controlling the voltage, we control the thickness of the oxide and therefore the color.

These techniques, plus precise masking, countless hours of experimentation, and a few other secret tricks, give us an unmatched ability to create unique and personal but timeless finishes that are lighter and more durable than paint or decals.

Integrated Seatposts (ISPs) look great, giving bikes a racier, more unified, more tailored look. The challenge, however, has always been to build ISP frames that do not create any sacrifice to ride quality or function. Too often, ISPs will use oversized seat masts that create a harsh ride, or strange seat clamps that limit adjustability and/or are difficult to adjust to start with.

Our proprietary tapered carbon ISP solves all of those challenges. The custom mandrel rolled tube, made for us by Enve Composites in Utah, is larger at the base, smaller at the top, and laid up specifically to ensure a stiff drivetrain and smooth ride. The outer layer of woven carbon reinforces the tube so we can safely cut it to size and clamp on our exclusive titanium ISP topper. That topper offers 1.5cm of adjustment, up and down, providing more than enough room for normal fit changes, and is precisely machined to fit Enve’s easy to use and super secure 2-bolt seat rail clamp design.

Our Carbon ISP has been extensively tested by elite cross racer Dani Arman on the gnarliest of Colorado adventures. Read all about her feedback here. TLDR: she loves it.

Big tires, road chainrings? Bigger tires, road chainrings, shorter chainstays? Maybe make the tires just a bit bigger?

We have received request after request for more tire clearance on Gravel and Road Plus bikes, for good reason. Bigger tires have more traction and are more comfortable, making a bike more capable on rough terrain. At some point, though, we are limited by the ever decreasing gap between the chainrings and the tire. There is only so much you can squish a tube. So we decided to stop using a tube.

Our 3D-printed titanium chainstay yoke threads the needle between road compact chainrings and up to 700cx45mm or 650bx53mm tires (or even bigger, depending on the exact component and geometry options) with the shortest possible chainstay length. Designed to plug neatly into a 1” chainstay and with two latticed support ridges printed laterally in the yoke, it delivers category leading tire clearance and remarkable stiffness in an elegant and lightweight package that has passed the strictest fatigue tests with flying colors.

Big tires, road chainrings? Bigger tires, road chainrings, shorter chainstays? Maybe make the tires just a bit bigger?

We have received request after request for more tire clearance on Gravel and Road Plus bikes, for good reason. Bigger tires have more traction and are more comfortable, making a bike more capable on rough terrain. At some point, though, we are limited by the ever decreasing gap between the chainrings and the tire. There is only so much you can squish a tube. So we decided to stop using a tube.

Our 3D-printed titanium chainstay yoke threads the needle between road compact chainrings and up to 700cx45mm or 650bx53mm tires (or even bigger, depending on the exact component and geometry options) with the shortest possible chainstay length. Designed to plug neatly into a 1” chainstay and with two latticed support ridges printed laterally in the yoke, it delivers category leading tire clearance and remarkable stiffness in an elegant and lightweight package that has passed the strictest fatigue tests with flying colors.

We offer three different head tube options to match your desired ride quality and component preferences.

The 1 ⅛” head tube is perfect for rim brake road bikes where a classic look and smooth ride quality are top priorities. It is also a great choice for touring bikes with steel forks. This is the base option on our Road and Utility models.

The Straight Oversized Head Tube is one of our two oversized head tube options. Its larger diameter makes it significantly stiffer than a 1 ⅛” head tube, and most importantly makes it compatible with forks that have tapered steerer tubes, as almost all carbon forks do. The Straight Oversized Head Tube is one diameter from the top to the bottom and fits a partially external headset, providing a modern feel with a more classic look. This is the base option on our Road Plus, All-Road, Cross, and Mountain models.

The most advanced option is our Tapered Oversized Head Tube. It also fits tapered forks like the Straight Oversized Head Tube, but it does so with a more sleek integrated headset instead of an external headset. We fully redesigned our Tapered Head Tube in 2020, and now build each head tube in house with a proprietary 3-piece design. The result wastes significantly less Ti during machining, allows us to build head tubes to any length to the mm, and reduces the weight compared to both the Straight Head Tubes and the previous Tapered design. And because the head tube parts are machined by the same machinist as makes our headsets, seat collars, and stem and seatpost parts, the Tapered Head Tube now better matches the design language of the rest of the frameset.

We offer three different bottom bracket shell options. As with the head tube designs, we can select different bottom brackets to match your desired ride quality and component preferences.

The standard option on most of our frames, and the option we usually recommend, is a BSA threaded bottom bracket. It is the easiest to service, fits almost every crankset available, and is compatible with the widest range of bottom bracket manufacturers.

There are a few scenarios in which one of our two oversized bottom bracket shell options, PF30 and T47, can be helpful. The PF30 and T47 shells are 50mm in diameter, making them slightly stiffer than the 38mm BSA shells. If you are seeking maximum stiffness, a PF30 or T47 bottom bracket shell will help us deliver that feel.

The larger diameter of PF30 and T47 (same diameter, but threaded) bottom bracket shells is especially helpful with Ti-Carbon frames. We will use a 42mm carbon fiber down tube when our goal is to maximize stiffness on a Ti-Carbon frame. Because that down tube is round and can’t be bent, we need to use a larger bottom bracket shell to match that larger down tube diameter. That is not necessary with full Ti frames because we can ovalize the Ti tubing to fit any bottom bracket shell.

The final scenario in which a larger bottom bracket shell is helpful is when riders want to use cranks with oversized axles (like SRAM AXS, eeWings, or Praxis) and need to fit Di2 or dynamo light wires through the bottom bracket shell. A BSA bottom bracket does not leave space for both, but a T47 of PF30 makes that combo a breeze.

In our experience, properly installed T47 and PF30 bottom brackets are both super reliable, so some of the choice between the two just comes down to what bottom brackets are available to match the crank specifications. However, some folks understandably prefer the ease of maintenance that comes with a threaded bottom bracket, and in that case the T47 is the perfect choice.

All three bottom bracket styles are available in 68mm and 73mm widths for road and mountain cranksets, respectively. We can also build fat bikes with 100mm wide BSA bottom brackets.

The tire and chainring clearance challenges that we first solved with our 3D printed chainstay yoke for Gravel and Road Plus bikes is an even bigger challenge for mountain bikes, especially as riders seek super short chainstays. Not only do we have to create clearance for both wide tires and the chainring, but we also have to add extra space behind the seat tube so the tire doesn’t hit the frame. Our new 3D clearance system for ATB and Mountain models solves that puzzle.

The 1x specific yoke threads the gap between 29×2.6” tires and up to a 40t chainring with a 52mm chainline, all with super short 430mm chainstays. (The design also gives us flexibility to accommodate up to 42t chainrings with a 47.5mm gravel chainline, which just reduces tire clearance to 29×2.2″. Choose our Gravel model for bigger chainrings.). The 3D printed seat tube knuckle then shifts the seat tube forward, creating space for the tire behind the seat tube while giving the frame a perfectly consistent seat tube bend for a precise frame geometry and saddle position every time. The short design of the knuckle also allows for a longer straight segment above the bend than with a simple curved tube, leaving plenty of space for long travel dropper seatposts.

Carbon Neutral Manufacturing