Bikes of the Bunch: Darren Baum’s Orbis titanium road disc

by Matt Wikstrom


It’s quite unusual for a rider to have the skills to build their own frame let alone make a successful business out of it. Yet that’s what Darren Baum has been doing for the last 20 years. In this edition of Bikes of the Bunch, we take a look at Darren’s new road bike and get his thoughts on disc brakes for the road.


Darren Baum started welding his own frames when he was a teenager and he hasn’t really stopped since. He is a trained aircraft engineer and worked in the industry before he started selling frames with his name on them in 1996. While he is perhaps best known for his titanium frames, he also works with steel and was trained in traditional methods before devoting himself to TIG-welding.

There will always be a potential conflict of interest when talking to any framebuilder about their wares, but few would deny their curiosity when it comes to learning more about the bikes they chose to build for themselves. And in the case of Darren Baum, who has a reputation as a discerning road cyclist that insists on testing every product his workshop offers his customers, there was sure to be a very good reason behind all of his choices.

Which brings us to the Orbis, a titanium road disc frame that is the newest addition to Baum’s catalogue. At face value, it may be just another in a long line of new releases built to satisfy the growing road disc market, however it was a bike that Darren had been waiting to build for quite some time. Indeed, he describes the drive behind the Orbis as very personal.

“For me, road disc is all about a bigger and livelier tyre,” said Baum. “Something that I’d been preaching to people for a long time was bigger-bagged tyres with plenty of clearance. Not for gravel riding, but for riding on the road. For bringing back that nice compliant feel and disc brakes are really opening up the ability to do that. We’ve gone on with this stiffness thing too long.

“When I started building frames, all the tyre sizes were more or less the same, and the components were the same, so I could just tune the frame and there was no need to worry about the bike as a complete package. Now, when we design a bike, we very much look at it as a complete package. We’re not just making a frame, and for me, the biggest challenge is not making the bike too stiff.

“I’ve designed the Orbis as a road bike, and just because it can take a tyre up to a measured 34mm, I’m not saying it’s a gravel-grinder. I think this is where road bikes will end up. But it’s not going to be for everyone. Some people are always going to love 25mm tyres pumped up to 110psi for riding on smooth asphalt roads.”

A false start then a lengthy development period

The Orbis is not Baum’s first foray into road disc. “We had been making road disc bikes but I wasn’t happy where they were with the axles and brake standards,” said Baum. “So we took that model off the market because I didn’t want anybody spending a lot of money on a bike and then all of a sudden it was out of date.”

From that point it would take Baum two years to finalise the design of the Orbis. There were many reasons for the extended design and development period, starting with the slow emergence of a dominant standard for brakes, axles, rotors, and wheels. “All the way through designing this one, I was trying to be on the standard as early as possible without picking the wrong one.”

That didn’t stop his customers from expressing an interest in the new bike, though. “This was the worst kept secret going around,” he said. “It was also the first time that I had people pre-order a product before I’d designed it.”

In the end, Baum had to design and manufacture new chainstays, seatstays, dropouts, and a head tube, plus, incorporate a new bottom bracket standard for the Orbis. In the context of discrete frame sizing, this would have been a massive undertaking. However Darren had to accomplish it all so that each frame member could be scaled and adjusted to the millimetre so that the size and geometry of was completely customisable while preserving the proportions and aesthetics of the frame’s overall design.

“That’s where two years quickly disappeared. It’s not acceptable to tell a customer that their bike is going to look ugly because I haven’t worked out a set of good-looking stays for a tall bike yet. I normally start with a 56cm frame and make that look good and then I work out how it will look at the extremes with a couple of random sizes in between. The annoying thing with this is, when I get all this right, nobody notices it. But that’s the aim for the frame, the fit, and the whole bike.”

The little things matter

Listening to Baum describe all of the effort that went into finalising the design of the Orbis, what struck me most was how much attention he gives to the little details. In some cases, it was a matter of a craftsman getting things to “look right” but his primary preoccupation is always with the utility of the bike. “I want to make a product that will stand the test of time,” he said, “and works so well that you forget about it.”

Take, for example, the chainstays of the Orbis. They originate from the bottom bracket in an oval shape and morph into a square section at the dropouts. A neat display of the workshop prowess, perhaps, but there is a lot more to the thinking behind the design.

“I ride rough country roads and I hate chain-slap,” said Darren, “so getting the drive-side chainstay low enough was a really big consideration. At the same time, the flat mount for the brake on the non-drive-side needed to be quite high.

“So, I decided quite early on that I wanted asymmetrical chainstays. I wanted good heel clearance and a good minimum chainstay length. I came up with a square-oval shape for the chainstays that gave enough clearance for the tyre and a nice flat area for the flat mount brakes that cosmetically I really liked. The engineering was good and it also allowed us to get rid of a fair bit of height for the chain clearance.

“That set off a process of learning how to make a square shape from a round tube, which required a fair bit of research and new tooling. From a practical point of view, we wanted the chainstays to originate from the same plane on the bottom bracket. That meant that the left chainstay needed a compound curve, so it bends outwards and upwards at the same time.

“The final aim was to make that optical illusion where the two chainstays looked the same. When you look at them from above, they look identical, which was important to me, and from the side, it’s hard to spot the difference.”

The dropouts also received the same kind of consideration before they were tweaked to satisfy Darren’s critical eye. “It quickly became clear that we were going to need a proprietary dropout to meet all of our different demands. A lot of the dropouts that are out there were designed around a 13T cog. We planned for a 10T cog and a single chainring, which was something that we had already gone through with our MTB frames.

“I also wanted it to be quite square and angular with slight rounding, so it matches in really nicely with the Dura-Ace flat mount brakes.”

Baum’s experience with building MTB frames also proved invaluable when deciding upon axles for the Orbis. “We found that the Syntace axle works the best from an alignment point of view with skinnier dropout. It’s a system that when it first came out, I kept encouraging everyone to adopt. Other systems work equally as well but when you’re manufacturing and aligning a frame, the Syntace system works the best. It’s the only system where the alignment of the axle can be adjusted because it has an eccentric bush on one side.”

Tyres, head tubes and bottom brackets

Amongst the many challenges that Baum had to contend with during the development of the Orbis was a quiet evolution in tyre sizes and rim widths. Both were on the increase and it wasn’t clear where they would end up. “We had to keep creating more clearance, which lead to us splitting the model [Orbis and Orbis R]. We also had to create a new language for how we talk about tyre size, which is why we now talk about measured sizes.”

This last point acknowledges the impact that the width of a rim can have on the final width of the tyre. As a result, Baum pays attention to what can be measured rather than what is declared on the side of the tyre. Darren eventually settled on a maximum width of 34mm for the Orbis while the Orbis R will take tyres that measure up to 28mm wide.

Making room for wider tyres had ramifications for more than just the stays. A new head tube was also required. “This was the first time we’ve done an internal headset and the reason for that was size-related,” explained Baum. “The bigger tyres that measure up to 34mm wide are also a lot taller, which means the new forks are taller, however our customers weren’t getting any taller.

“The length of our head tubes has always been a resultant that is adjusted to the millimetre to suit the height of the handlebars for each customer. So all of a sudden we had the problem of making a new head tube to the millimetre in-house and that required a new four-tonne machine.

“We also had to find a headset that satisfied our demands for durability, so we had one on a gravel bike for a long time, and it held up. We also put it into some mountain bikes, and it held up, too. So before we released it to the customer, we had ridden it and serviced it and knew that it was really going to hold up.”

A new bottom bracket standard was also adopted for the Orbis. “We decided to go with the T47 because it allows 24mm and 30mm crank axles, internal cable routing for the hydro brake, and is threaded so it won’t creak.

“One thing that took us quite a long time to actually work out was bottom bracket height and ride height. This was the kind of thing that I originally worked out by feel but we didn’t know if the new, bigger tyres actually compressed more. It was quite hilarious. Everyone in the factory got to sit on a bike with scales and measuring gauges and we tested across a range of tyre pressures to see what was going on.

“Bikes have traditionally been built too tall and they’ve probably stayed too tall out of tradition due to older pedals platforms striking the ground. That got solved a long time ago and tyre sizes have been creeping up since then, so it kind of feels as if the industry hasn’t had a reset. So we went back to the formulas we had been using and tested them in the factory to see if we were on the right track with the new tyres. And in the end, our bottom brackets are now a little lower.”

A new bike for the boss

It’s easy to imagine framebuilders could get into the habit of building a new bike for themselves on a regular basis, but in Darren Baum’s case, it doesn’t happen often. “I’m an odd size and really hate obsolescence, so the bikes I build myself are going to be around for a long time. The bike I ride the most, a Ristretto, is 7-8 years old.”

Indeed, his new Orbis is just the 12th bike for his collection that spans some three decades of framebuilding. “Building up a new bike is nerve-wracking because I’m always deciding between building a bike that is truly for me or for testing something like new geometry or the durability of the head tube or a bottom bracket shell.”

Committing to the new bike marked the culmination of the development process for the Orbis and Darren was prepared to indulge a little with an extravagant yet impractical paint scheme. “A paint manufacturer showed us some bright new colours and that sparked it off. It reminded me of a bike that I couldn’t afford when I was a kid, a Fat Chance Yo Eddy, a bike that I always wanted, and so the inspiration came from that.

“I didn’t want to make a direct copy and I hadn’t really ever seen fades in matte. It’s different, kind of being lairy without really being lairy, but it’s really impractical. A bright yellow front end in matte … I wouldn’t recommend it to a customer, so this was just a pure indulgence, making exactly what I wanted.”

Frame: Baum Orbis custom titanium road disc
Fork: Enve Road Disc
Headset: Cane Creek
Groupset: Dura-Ace R9170 Di2, 50/34T cranks, 11-30T cassette, 140mm rotors
Wheels: Enve SES 4.5 AR Disc with Chris King R45D Centerlock hubs
Tyres: Schwalbe Pro One tubeless, 28C
Handlebars: 3T Ergonova
Stem: 3T Arx II
Seatpost: Zipp SL Speed
Saddle: SMP with Busyman Bicycles custom upholstery
Pedals: Speedplay
Bar tape: Busyman Bicycles
Cages: King
Pump: Silca Impero

As for the build, Darren’s choice of components was based on practical considerations as much as aesthetics, along with a little necessity. “The big feature that swayed me with choosing Dura-Ace this time was this: a lot of the time, I ride in the dark and you can’t always know what gear you’re in or see how far up the cassette you are. Having Synchro Shift do the work for you is wonderful. I wouldn’t use it in a bunch, or racing, but by myself out on the back roads where I do a lot of my riding, it’s perfect.”

That’s not the only feature that Baum appreciates, though. He also points to the new 30T cog for the rear cassette, matching cranks with a powermeter (that are on back-order), and Ice Tech rotors for the brakes. There’s also the fact that the ergonomics of the levers are largely unaffected by the braking and shifting options, so he can preserve his fit from one bike to the next.

Darren’s choice of rims and tyres were designed to deliver comfort. “The roads I ride on are coarse chip-rock, bad country roads, off-camber, bumpy, patched. There’s gravel and there’s potholes. I went with Enve’s AR wheels and Schwalbe Pro One tubeless tyres [28C], and that combination comes out at be a measured 32mm. With my weight of 80kg, I run a front tyre pressure of 41psi and a rear pressure of 50psi, and that extra comfort was what I was really looking for.”

As for the hubs, “I’ve been a fan of Chris King hubs for a long time and they don’t go out of fashion. They look good now and they’ll look good in 10 years, which is important for a bike that you plan to hold onto for a long time.”

With a brightly coloured frameset, some might have expected a bit more colour in the finishing kit, but for Baum, the black parts and glossy surfaces ensure that the colours of the frame pop. Of course, with a stem, handlebars, seatpost and pump painted to match the frame, there’s arguably more colour on display than what could be achieved with coloured components.

It’s not uncommon to see Busyman Bicycles’ custom bar tape and saddles on a Baum bike. Baum has worked with Mick Peel for several years and continues to praise his work. “I’d like to think that I’ve made it to being an artisan or master craftsman, or something like that, but coming across somebody that just out-crafts you, it leaves you a little speechless. For me, to be able to get in touch with Mick and show him what I’ve come up with and have him rip it out and match it to perfection is really cool.”

“The thing that I love to hate is the seat. I only ever started riding SMP’s saddles about 10 years ago because some of my customers were asking for them. So I put one on to test it out. It was the ugliest seat I’d ever seen and I didn’t like it, but it has become my go-to saddle. The only time it comes off my bikes now is when I’m testing something new. The shape works really well for me, and if I spend any time off the bike, it’s the one saddle that still feels comfortable when I get back on it.

The remainder of the build comprises parts that are familiar favourites, such as the 3T bars and stem, with one exception. “Quite often, there’s one or two things that I’m testing on my personal bike so I can educate my customers, and the Zipp seatpost is one of those. I really need that first-hand experience at the side of the road when it’s cold and the hands aren’t working the best to understand how it works.”

The final word

“It’s a keeper. I’m proud of how the final product came out. To be honest, first ride, I hopped on it and it did exactly what it was supposed to do and I forgot about it really quickly. That means it did its job.

“It isn’t until I come to a tram line or a rough crossing, where I’d normally brace myself for a harsh impact, that I go ‘Wow, this is smooth.’ We’ve got some bad corners around here, off-camber and covered in gravel, and where I always feel a bit nervous, but on this bike, I just scream around it.

“So, it’s not so much about what it does, it’s what it doesn’t do. What feedback it doesn’t give you, and that, I’m really quite happy with.”

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