Framework Bicycles presents a clean modern aesthetic while evoking manufacturing techniques reminiscent of the first carbon bikes. This spring we set storytelling reviewer Morgan Taylor loose with Framework to design and review a custom bike to their specifications. In the first of a two-part series chronicling what they’ve come to call the “black rainbow” project, Morgan digs in to the beginnings of Framework and how they intend to shake things up in the custom bike world.

Michelangelo Buonarroti is responsible for some of the most well-known works of the Italian Renaissance. Michelangelo is known for reluctantly having painted incredible frescoes on the ceiling of the Sistine Chapel and for engineering and overseeing the construction of the massive dome at St. Peter’s Basilica, but his heart was in carving sublime sculptures with marble from the famed quarries of Carrara in northern Tuscany.

Of his preferred form of expression, Michelangelo is credited with saying “ogni blocco di pietra ha al suo interno una statua ed è compito dello scultore scoprirla” – that each block of stone has a statue inside and it is the sculptor’s job to discover it. By far, Michelangelo’s most famous piece is his 17-foot tall rendition of a recurring Florentine subject, David. In Renaissance Florence, representations of David evoked the strength and courage of the mythological Hercules.

Of course, the David in question is that of David and Goliath, a classic underdog story referenced well beyond its biblical roots. Jonathan Hornell-Kennedy, the brains behind Framework Bicycles, can’t help but question the way things are done in the bike world. And I can’t help but make an analogy between Framework’s David and the greater bike industry’s Goliath – even the smaller makers in the bespoke custom sphere Framework inhabits.

Approaching making bikes from the perspective of a skilled machinist, Jonathan is looking to disrupt how we think about custom bikes and to do it for less money than the major players. Equipped with high tech milling machines and carefully crafted blocks of 7075 aluminum rather than chisel and stone, Jonathan is showing us how the art of machining can bring some rather impressive results.

Art is subjective, yet Framework’s bikes are objectively interesting. The viewer is invited to look closely, with fine details revealing themselves upon closer inspection. There is a sense of wonder about process, an appreciation for craft. And in an age where additive process – 3D printing – is getting a lot of buzz, Jonathan’s transparency in his reductive approach to manufacturing is making waves among those willing to listen.

Prelude to a Review

When I first came across Framework Bikes on Instagram last year, I saw a super clean modern aesthetic blended with a manufacturing technique reminiscent of the first carbon bikes. And while carbon tubes bonded into milled aluminum lugs will bring back memories for long time bike geeks, there’s a lot more going on at Framework’s shop in Hamilton, Ontario. Of course, Framework doesn’t resemble your usual small frame building shop: it’s bright and squeaky clean, with big milling machines and custom-made fixtures taking up most of the floor area.

When the opportunity came up to work with Framework to design a custom bike for review, my brain whirled with possibilities. Of course I came to the table with ideas in mind, excited for the prospect of a bike built around my unique fit needs and with geometry to my specifications. Jonathan and I threw around ideas and I considered what kind of ride I might like to create. A few messages back and forth and Jonathan had a screen grab of the Solidworks model ready for me to consider.

How Framework Came to Be

As an experienced machinist, Jonathan’s mind is always at work. Historically he’s worked for other people so they can make their products – that includes work for the aerospace, medical, and automotive industries. But since that’s a contract-based business, Jonathan wanted to have something to do in the inevitable downtime. That’s the beginning of the story of Framework Bicycles. A passion project, but hopefully one that can do more than just fill the gaps between contracts.

Not happy to simply make himself a bike, Jonathan sought to create a repeatable process that reduces human labor, prioritizes accuracy, and keeps as much of the production process right in his own shop as possible. With an idea in mind and the machines at his disposal, Jonathan developed a parametric 3D model to build his first bike that would set the stage for every future bike to come out of his shop.

The Parametric 3D Model

The heart of Framework’s manufacturing process is a parametric 3D model, where aspects of frame geometry can be entered and the model will automatically adapt all of the 3D surfaces. While the model does show tubes and wheels for the sake of checking clearances and envisioning the final product, it’s really built around five billets of 7075 aluminum: the head tube, bottom bracket, seat cluster, and dropouts.

The model’s real magic is in its hidden layers: with a click of a button, Jonathan can reveal how each aluminum billet will be held by the milling machine – and more importantly, exactly how it will be milled.

When you change a single parameter, such as making the chainstay longer, the angle of the tube between the bottom bracket and the dropout changes ever so slightly. The software automatically recalculates the angle of all of those joints each time a change is made. Shorter seat tube? Steeper angle to the head tube. Different angle at each end of the top tube.

So the precision is built right in to the model. Every joint is going to be exactly where it needs to be, and the model will tell you exactly how long your tubes need to be to connect them. And this, as a result, is how Framework’s process is so easily repeatable and also so easily scalable.

I was absolutely mystified watching the model recalculate after Jonathan changed a parameter, and asked for a further explanation.

Jonathan asked me to think about what a TIG or fillet brazed frame would look like before any junctions were finalized: tubes mitered to meet each other without any gaps. His model starts from a similar point. From this point, he can specify within the model how much “fillet” to put into the joints, at what radius, and so on. Now keep in mind we’re still talking about a reductive process; there’s no fillet per se. Framework’s aluminum parts are freed from their blocks like Michelangelo intended.

While this part was tough for me to wrap my head around, Jonathan says it’s actually simpler than the milling process – and that machinists are more impressed with how he’s programmed the operations to finish each piece without having to reposition them in a 4-axis CNC machine. Each piece is sculpted in a single operation in the milling machine, which changes its own tools. Jonathan drops the 7075 billets into the machine, and they come out ready for plating.

Materials Choices

While the use of lugged carbon and aluminum is nostalgia-inducing, make no mistake that it is wholly intentional. In implementing different materials in different places, Jonathan describes the idea of breaking a big problem up into smaller problems, and finding the right solution for each of those on their own. He is adamant that aluminum is a great choice for the joints, as it behaves similarly regardless of the direction a force is applied – and that carbon, which responds best when loads are applied in a controlled manner with respect to fiber orientation, offers a lot of customizability in the tubes.

Given the legendary status of titanium in bicycle manufacturing, folks often ask why Jonathan isn’t using ti for the lugs. And to this Jonathan would say why would you? Ti is more expensive to source, much more expensive to machine, and wouldn’t yield a lighter part since aluminum and titanium have functionally equivalent specific strengths. If you follow along on IG, you’ll also see that it’s no secret that Jonathan doesn’t think 3D printing is the best solution: he’s quite proud of his single-step aluminum milling process with no human labor post-work required.

Having seen what Jonathan is up to in his shop, I’m also confident he could be machining his own molds to make lighter weight, full carbon monocoque frames. His response to this comment is that while a full carbon layup might end up lighter, you lose the ability to do true custom geo, and with less precision at the bearing interfaces. By using milled aluminum, the bottom bracket and headset bearing seats are exactly where they should be, and the process is easily adaptable to a different custom geometry each time the machines are loaded.

Another comment I’ve heard repeatedly is the potential issue of galvanic corrosion, where carbon fibers conduct electrical current to a corrosive material and weaken the bond between them. Since (once again) this isn’t my area of expertise, I asked Jonathan how he accommodates for this. His first comment is that any production carbon part with metal interfaces is subject to the same issues, and that bonding technologies are much different than they were in the early days of carbon.

Framework’s approach to keeping the aluminum separate from the carbon is two-fold: the aluminum parts are treated using electroless nickel plating to create a barrier (which also prevents oxidation on the outside surfaces), and the bonding agent uses glass microspheres to prevent direct contact between the tube and the lug. Bottom line, if you’re worried about galvanic corrosion in this context, there are a lot more parts with metal-in-carbon for you to look into.

Perhaps the most intriguing thing about Framework’s approach is how transparent they are in showing off their process. Have a look back through their Instagram page for tons of video content showing exactly how Jonathan makes a frame from start to finish. From Solidworks to machining, winding carbon tubes to gluing up the finished product in the jig, every step of the way is laid bare, and Jonathan’s happy to discuss the process.

Blessings and Curses

With Framework’s parametric model, there really are no limits on what you can do with both fit and handling geometry. This could be both a blessing and a curse. On one hand, you can have a bike tailored to your unique needs, or have something built that steps beyond current norms. On the other hand, you risk commissioning your very own Homer Car – a machine that might express your ideas, but not hit the mark out in the real world.

To a large extent when we commission custom work, specifically a bike frame, we put our trust in the builder to make choices that will align with our needs. To that end, Jonathan is the first to admit he’s not a bike fitter. He’s very much capable of transposing the fit data from your current favorite bike to Framework’s 3D model, or to replicate the geometry of a bike you already like.

But, he still recommends working with a professional fitter to make sure you’ve carefully considered this aspect of the build before the metal hits the mill. Having worked in bike fit myself, I think Jonathan’s partnerships with fit-focused bike shops will prove valuable to his business, even if it costs the customer more to work with these shops. While Jonathan can certainly work from your current bike, the idea of dropping a bunch of money on a fit that hasn’t been fully considered leaves questions unanswered.

As with all custom bikes, the buyer who is going to get the most out of Framework’s process is someone who doesn’t fit the mold (ha!) of a usual bike buyer. Extra tall, extra small, unique fit requirements. But there’s also the buyer who’s simply curious about commissioning a work of art.

With the design and manufacturing side of the business, Jonathan is all about reducing human labor. While those processes are very much dialed and efficient, the customer-facing parts of the custom product world have potential to be a huge time suck. Time will tell if Jonathan finds the customer service aspect of the business significant enough to increase prices.

From Making Fixtures to Winding Carbon Tubes

If the no-post-work finish on the machined parts of Framework’s bikes didn’t tell enough of this story, looking around the shop you’ll also see a number of fixtures, molds, and the frame jig, all made in house. At this point you understand that Jonathan is an extremely skilled problem solver.

While my Framework is built with filament-wound carbon tubes from US-based supplier Rockwest, Jonathan is now making his own tubes to have even more control over the production process. Jonathan’s process of trial and error in moving from off-the-shelf to custom wound tubes over the past six months has been quite interesting.

Taking carbon fiber ribbon and turning it into rideable tubes is another bit of black magic. But, seeing Jonathan work through the challenges of building his own system from scratch has been really cool. With in-house carbon tubes, Jonathan now has significantly more control over the outcomes of his products, with respect to tube shapes, wall thicknesses, and flex characteristics.

Now that Jonathan is making his own tubes, he has control over every part of the frame, and he has his sights set on how he can bring more aspects of the bike into his own hands.

Chainrings, Cranks, and Commitment to Press Fit

In addition to the parametric model for the frame parts, Jonathan has created his own crank and spindle system which can also be adapted based on parameters. This means you can get cranks in any length you want, including extra-short ones if you’re curious or your body needs that. Since numbers matter, I asked Jonathan to make the very first cranks down to the third decimal place: say hello to the world’s only 169.420mm crank arms.

In another move that will irk some folks, Jonathan is a big proponent of press-fit bearings – with a caveat. Bearing seats bonded or molded into carbon frames simply aren’t accurate enough for Jonathan’s standards. He’s confident that the inevitable variation between such frames is responsible for the complaints people have about press-fit systems. To counter those complaints, Jonathan claims his precision-milled components and his process for bonding the frames creates a system more accurate than any thread-in or press-fit bottom bracket.

He’s so confident, in fact, that his custom-made crank and spindle design doesn’t provide any accommodation for bearing preload. Everything is milled to exact dimensions, and an expanding collet locks the crank arm into place when the crank bolt is tightened down. In addition to the parametric crank arm design, Jonathan also makes his own 1x narrow-wide chainrings or spiders to match his cranks to rings of your choice.

As with the crank project – where Framework’s milling machines make every piece from spindle, crank, fixing bolt, and chainring – Jonathan also makes as many of the small parts as he can, including the headset bearing cover that interfaces seamlessly with the head tube and accommodates internally-routed cables, as well as bottle bosses, ports for where cables exit frame tubes, and derailleur hangers.

Downsides and Limitations

Of course, there are limitations to the lugged carbon design. First of all, there’s no question that these frames will be heavier than monocoque carbon layups. Jonathan tells me that his frames generally come in between 1100-1250 grams. That’s 500-600g more than the lightest production monocoque frames, but still a couple hundred grams lighter than a Titanium frame.

Another factor that can’t be ignored is aerodynamics. While Jonathan’s preferred build with internally-routed cables keeps things clean, it’s well known that round tubes are less efficient at cutting through the air. Again, this is only an issue in comparison to monocoque carbon, as metal bikes all have round tubes.

As with all custom frames, there’s a lot of trust put in the builder to have their secret sauce dialed in. Bastion, who make custom frames with 3D-printed ti lugs and carbon tubes, claim to be able to use software to determine your perfect flex point. I find this idea intriguing as I’ve been actively chasing frames with the perfect flex (for me) for nearly a decade. Jonathan and I have discussed this at length and I’ll get deep into that topic in the second part of this story.

Lastly, depending on how much freedom Jonathan gives to individual customers, they may be capable of producing their own Homer Car. But, given the bikes I’ve seen coming out of the shop, I think Jonathan would steer people away from making truly bad decisions. (That said, when designing my bike, Jonathan was sure I was making my very own Homer. That’s another can of worms we’ll open up later.)

How About Price / Why So Cheap?

So, how much will a Framework build set you back?

Having heard all about the process, you’re probably wondering how much these things cost. Being based in Canada, Framework’s products are priced in CAD: $5500 for a frame, fork, and headset (that’s just over $4000 USD at time of writing). Add another $500 for an integrated stem-bar. And a set of those custom-machined cranks with a single ring: $1500.

I’ve questioned Jonathan extensively about the relative “affordability” of his frames in comparison to others occupying a similar space—most notably Bastion—whose complete builds are in the $16-19K USD range. His answer is similar to many small shop builders: at this point he just wants to keep the lights on, and see people riding his bikes. He doesn’t want to charge more just because he can. He laments the fact that partner shops will have to tack on additional cost to his base price to sell Framework frames.

Yet there’s another distinction between Framework’s process and those using 3D-printed lugs like Atherton and Bastion: Jonathan says that his process is significantly less expensive. Currently, additive processes require a lot of post-work: sanding and machining to bring a raw printed part to finished product. Framework’s lugs come off the machine, straight to plating, and are ready for assembly.

Jonathan always comes back to human time being the most expensive part of manufacturing, with the greatest possibility for error. As long as he can get away without hiring more people to do jobs that machines can do, he will keep prices as low as he can. In the future, it’s quite possible we’ll see a more basic “stock geometry” option and a “full custom” a-la-carte option for those who want their own Homer.

Rebirth

The word renaissance is French for rebirth, an idea that I find applies to what Jonathan is doing with Framework. Can precision machining and modern bonding technologies bring about a rebirth of lug-and-tube construction in bicycles? Will this potentially less expensive option disrupt the way we think about custom bicycles? Witnessing Jonathan freeing those sculptural works from blocks of 7075 and connecting them with filament-wound carbon – it’s enjoyable to be along for the ride.

In the follow-up to this piece, I’ll get into the details of designing and riding my custom “black rainbow” build from Framework. Orchestral composer Charlotte Bray refers to a black rainbow as “a metaphor for something sought after but impossible to attain, an alluring ongoing search” and I feel like that perfectly encapsulates the search for the ideal frame. I’ve got plenty to say about frame flex, and finally getting a bike designed completely around my unusual fit geometry. Will I end up with a David, my very own Homer, or possibly both…