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Wizards of Aus: Inside custom bike builder Bastion

In-depth
7 Aug 2019
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This article was originally published in Issue 87 of Cyclist Magazine

Words Peter Stuart Photography Matt Ben Stone

A laser fires and a blinding light begins to radiate over a pile of titanium dust. White-hot metal particles streak off the build plate like tiny fireworks.

The dusty pile seems to be growing as the laser moves very slowly back and forth over the powder.

Beneath that powder – almost magically – a titanium lug has grown from the base of the machine. It feels like some sci-fi vision of what the future of bicycle manufacturing might look like.

In reality, it’s how Bastion builds parts for its frames today.

Every element of the production process takes place at Bastion’s facility in Fairfield, in the green suburbs of Melbourne, Australia. The showpiece is the 3D titanium printer, but it’s not the only technical marvel on display.

‘We’re engineers and we like to use technology,’ says Ben Schultz, Bastion’s founder and CEO, with a laugh as he shows us around the facility.

In one room sits a filament winder, which weaves ribbons of carbon fibre into tubes, all controlled by computers and robots. There’s an alloy CNC machine, a paint shop and a large heat-treatment furnace, as well as various ovens, industrial fridges and a blasting cabinet. It’s a bike geek’s paradise.

Bastion’s core staff all come from an automotive background, straight from Toyota’s R&D department. Their vision was to rethink bike design with far more control over customisation.

That meant considering not only the size and shape of the rider, but the ride quality and performance of the bike too.

Building by numbers

‘Technologically, our bikes are the most advanced out there,’ says engineering director James Woolcock. ‘Are they the most advanced in every aspect?

‘Well, no, because they don’t have any aerodynamic development.’

At Bastion, the focus is optimising ride quality through the manipulation of materials.

Back in the room where the carbon tubes are made, a strip of carbon fibre rolls slowly off a spool and is fed through a resin bath and wound over a mandrel to form a carbon chainstay, which will be attached to Bastion’s titanium bottom bracket.

The stunning chevron-weave pattern of the tubes is an unintended consequence of the production process, but has become an aesthetic signature for the frames. By creating its own carbon tubes in this way, Bastion can tune in any amount of stiffness it chooses.

To keep things simple for clients, the brand sticks to three options of torsional rigidity – regular, stiff or extra-stiff – but that’s just one aspect of the build that is customisable. The client can also decide how they want the bike to ride.

Once the customer has had a bike fit (done either in Fairfield or through a network of bike-fit partners around the world), Bastion can tweak a bike’s geometry to find a sweet spot of handling and performance that mimics other popular bikes.

In practice, that means a customer could ask for a sprinkling of Trek Madone mixed with a bit of Cannondale Synapse if they so desire.

‘Dean McGeary, our technical director, built our own simulation tool, mapping how certain material and geometry parameters influence the ride, based on parameters from other frames from other brands too,’ says Schultz.

‘Then we tested the first 30 to 40 bikes to see if they matched that simulation, and they did.’

These lugs are hysteretical

The custom-tuned carbon tubes are enough on their own to make Bastion stand out from the crowd, but there’s no doubt the real magic of Bastion’s frames is in the titanium lugs.

They are certainly stunning to look at, however the brand didn’t opt for them out of aesthetics.

‘Coming from a car background, we’ve done lots of work with suspension design,’ says Schultz. ‘Carbon fibre has what’s called hysteretic damping, or hysteresis.

‘What you normally have in a car is a fluid-based suspension system that will both spring back on large impacts and dampen smaller turbulence.’ Bikes made purely of carbon fibre don’t offer the same type of suspension because of their innate hysteresis.

‘The problem with carbon is when you vibrate it at 50-100 hertz it tends to lock out and doesn’t provide the same level of smoothness you get from a titanium or steel bike.

‘We found that by using just titanium at the joints you get the same effect on the ride quality as using a full titanium frame, so we still get that smooth ride but with the low weight, stiffness and vertical flex that carbon offers.’

Schultz adds, ‘Carbon lets you control the stiffness of the bike by controlling the layup of the fibre, so it’s the best material to use for the tubes. For the joints, though, we strongly believe titanium is the better option.

‘Aside from the hysteresis, carbon fibre has lots of quality issues in the joint areas. You have to use large amounts of it in lots of different directions to handle the loads.’

Bastion isn’t the only brand blending carbon tubes with titanium lugs, but it claims its process is unique.

‘Other custom builders make the titanium joints by welding tubes together,’ Schultz says. ‘That gives you the ride quality, but because it’s welded it lacks that torsional stiffness we get.’

Testy titanium

Bastion’s expertise in 3D titanium printing has provided it with a useful sideline in providing consulting services for other industries – ‘That’s growing quicker than the bike sales, to be honest,’ says Schultz – but while you may think the knowledge of 3D titanium printing came before bike design, it was actually the other way round.

‘We had zero experience of printing in titanium before Bastion, but we did have experience of additive manufacturing,’ says Woolcock.

‘We’d been using plastic printing for prototyping – just fitment trials and things like that. Then we heard about metal 3D printing. We thought the benefit would be that there is no real tooling [of moulds] so there’s no real cost.

‘Of course now we realise there are significant costs in time, with every bike being remade on the computer and pre-processed for printing, and there is a fair bit of labour in setting it up differently every time.

‘But there’s no tooling. We aren’t spending £20,000 tooling for each bike we make.’

The technology has its drawbacks compared to non-printed titanium, though.

Titanium has an underlying crystal structure, often called a grain, just like steel does. When you stretch, squeeze or crack those crystals it sacrifices the strength of the metal, and printing it from powder can interrupt that crystal structure.

However, the printers have come on significantly since their first inception. Where older machines sintered balls of metal together in a way that didn’t offer a huge amount of structural strength, the newest technology is very different.

‘The new machines now are melting or fusing the metal together,’ says Schultz. ‘The term “selective laser melting” is more accurate for our machine – really, it’s like a micro-welding process.

‘It starts on a plate of titanium and it welds the shape onto it and then it drops it by a tiny amount – 30 microns, less than a human hair.

‘The powder delivery system wipes a very thin layer of powder over the top of that and then the powder melts into the layer below it. It just keeps working its way up.’

The lugs also go through a heat-treatment furnace, to help create the grain structure that may have been fragmented by the printing process.

The result is titanium that isn’t as strong as machined billet titanium, but is much thinner and able to be controlled in more precise ways.

A close look at the finished lugs reveals the tiniest sculpted edges and even the thinnest-walled parts are effectively hollow, the insides made of an intricate latticework.

Straight off the printer, the lugs look like some kind of sci-fi set design, with thin towers of titanium propping up each part of the lug.

‘Those are supports,’ Woolcock explains. ‘The reason for those is if you’re building an overhanging shape and you’re melting each 30-micron layer it will eventually begin to sag under its own weight.

‘We design them [the supports] to snap in a structural way that doesn’t damage any part of the lug afterwards.’

With the supports snapped off, and heat treatment done, the lugs then travel to the blasting cabinet for finishing, and finally the titanium lugs and filament wound carbon are bonded together using aerospace adhesives to complete the frame.

From there it’s off to be painted in the paint shop, and then onwards to the customer.

Small is beautiful

The intricacy and customisation of the whole process means it is hard to envision Bastion scaling up its production. So is Schultz worried about a factory in the Far East picking up Bastion’s methods and doing it faster, bigger and cheaper?

‘The good thing is that the majority of the cost is actually the machine itself. Whether you get that in China or you buy that in Australia, the machine costs what the machine costs. It’s also still quite slow.

‘It’s well suited to a company building less than 200 bikes per year, but any more than that and it just doesn’t stack up. Those guys want the economies of scale where if you build 20,000 bikes, each one is a fraction of the cost compared to if you build 200.

‘So it’s not an attractive technology to the bigger manufacturers.’

With the patience and cost required for a build, it seems as though Bastion bikes will always target the niche, luxury side of cycling: ‘Whether it’s a Swiss watch or a supercar, I really believe that people yearn for something personalised and something unique,’ Schultz says.

‘Whatever the future holds for cycling, I really hope that there will always be a place for that in the bike market.’

Finished product

The Bastion Road can be built however you want it

With lugs printed in 6-4 grade titanium to any angles and dimensions, the Bastion Road can be adapted to any spec, physiological requirements and tyre clearance, opening a wide spectrum of possible ride qualities. What’s more, the lugs can be etched with any pattern or name.

‘People very regularly request their names to be etched on the bike, or their children’s names,’ says Ben Schultz, Bastion’s founder and CEO.

In terms of ride quality, the engineering team at Bastion tunes the geometry and stiffness to a specific ride criteria – or to match whichever type of bike you may be used to – and presents it in a ‘Custom Engineering Report’.

Back in issue 59 of Cyclist, we reviewed our own custom-made Bastion Road Disc (which has sadly long since been returned) and requested it to ride somewhere between a Cervélo R5 and Parlee Z-Zero.

The result, from our point of view, was impressively precise, with an engaging mixture of titanium smoothness and carbon rigidity.