Inside Actofive Factory Tour: German CNC-Machined MTB Gems, A Closer Look - Bikerumor

With the Bespoked custom bike show returning to Dresden starting tomorrow, let’s take a look inside Actofive Cycles, who machines beautiful mountain bikes in the German city. We’ve been closely following Actofive for a few years – from the development of their variable travel trail to enduro bikes, to their chainrings and modular cranksets. But we also had the unique chance to get a closer look behind the curtain on one of our last visits to Dresden.

Check out these machined aluminum gems with us, and some rare up-close looks at the inside of their machined masterpieces…

Fully CNC-machined, Actofive produces some of the most refined mountain bikes you will find anywhere in the cycling industry. But they are actually quite a small specialist manufacturer, sitting inside an old industrial building on the edge of Dresden, Germany.

Beneath, those old-school riveted steel trusses and tucked in with several other types of small manufacturers is a more contemporary box hiding the modern capabilities of Metzner Engineering and the home of Actofive Cycles.

Once inside the inner sanctum, a number of Actofive models and development prototypes hang on the wall of the unassuming workshop.

Really, there are 2 secrets that make Actofive.

One is the man behind the brand, Simon Metzner. And the other, the precise Portatec CNC milling machine. Working together, these two create every Actofive mountain bike and component.

The CNC-machine and several of its unique features are produced by the company of Simon’s father, primarily for the aerospace industry. But instead of taking over the business, Simon always had other ideas of how to use these machines. And with mountain biking being his passion, Simon Metzner went out on his own to start up Metzner Engineering, a contract CNC-manufacturing company created to allow him to also further his MTB component and bike development.

So by mixing his expertise in manufacturing process optimization, the CNC capabilities of his small workshop, and deep mountain bike design knowledge, Simon has developed Actofive into a sought-after small German mountain bike manufacturer creating true CNC-machined MTB gems.

We were first really introduced to Actofive’s high-pivot alloy P-Train about 3 years ago. But Simon has been working on that first adaptable-travel enduro bike for at least a few years longer, since 2018. That’s when he hung out his own shingle as Metzner Engineering, after leaving the family CNC machine production business.

In its first iteration, the bike started with a welded steel front & rear triangle joined together with CNC-machined alloy links. And it has continued to evolve in many iterations along the way. That original steel bike now sits in Simon’s office with a machined rear end quite similar to today’s production P-Train.

And while CNC-machining aluminum has always been kind of in Simon’s blood, he isn’t entirely beholden to one material, or even the subtractive machining process. He’s toyed with other materials – like titanium – and also with the potential of modern 3D-printing capabilities.

But machining aluminum has defined the development of Actofive’s bikes and components these last 6 years, especially the use of intricate and well-thought-out milling designs. And it forms the basis for Actofive’s unique clamshell, or sandwich construction.

And Simon continues to show that he has more ideas on how to refine both his designs and their manufacturing. So there’s plenty evolution left to do in CNC-machined aluminum.

Looking around the Actofive workshop during our factory tour showed a pretty good sample of their complete offering, in various stages of completion.

Here are a couple of I-Train trail bike front triangles. The two halves have each been machined from both sides – the outside that we can see, plus the intricate inside webbed truss structure that Actofive doesn’t let anyone else see.

We had a peek, and it’s even more impressive that the fine tool marks you see on the outside. The design of the inner structure allows Actofive the ability to fine-tune strength and stiffness at various locations within the mountain bike frame, while keeping it lightweight.

But Actofive is wary of giving away the secrets of how they achieve their balance of lightweight-to-strength. And especially resistant to give away the design of their interlocking system that is used to bond the two halves of a frame together to create the complete bike.

We also had a chance to watch some Actofive crankarms be machined in their first step during our factory tour.

The heart of everything that Actofive produces starts out as simple slab of aluminum billet.

And really, most of Actofive’s components come down to machining one side to get the final outside shape. Then, flipping it over (and securing it to a negative fixture on the milling machine) to hollow out the second side.

The simplest parts like their more affordable Signature X crankset, the P-train rear end, and the I-Train seatstays leave it at that, where you can see both sides that have been machined. But more complex hollow parts like the mountain bike front triangles & Signature cranks, get 2-sided machining for each frame half that are then bonded together to create the more complex hollow structure.

But of course, moving big heavy chunks of aluminum around is quite difficult before all that extra material is machined away (and collected for recycling). So Actofive has this nice little crane in their machining room, which allows Simon the ability to easily maneuver everything on his own.

And then, once held down on the milling machine’s worktable with a strong vacuum pressure, the intricate designs can be carved out of the raw billets of aluminum. Most often in densely packed, nested layouts to optimize the most amount of components out of a single piece of raw aluminum material.

Everything that Actofive produces in made in-house in the factory that we toured.

Simon has a design office upstairs directly over his machining room.

There everything is designed and refined in SolidWorks, creating the computer-aided design (CAD) data to drive the computer-aided manufacturing (CAM) processes one floor below.

Actofive’s specialty is creating 3 things. CAD/CAM data, metal filings, and out of that… precision machined alloy components.

The Portatec CNC mill is the brawn. But the brains of the Siemens controller manages all the machining processes, tooling, and where those tool cut. While Simon can remotely operate everything from his computer upstairs, for production, everything is handled directly at the machine. There’s so much raw data governing the machining process, this ensures that any potential minor breakdown in communication couldn’t negatively affect the final work.

Besides data, Actofive’s factory is covered with these small aluminum filings we saw in our tour.

Sure, the bulk of material gets efficiently collected for recycling, but plenty of chips fly around. That’s why machining happens in its own completely enclosed room. But every time Simon moves around to control the process, filings stick to his clothes & shoes. And since they’re not magnetic, it’s a chore to totally keep under control.

So he has separate clothes and shoes for working on bikes & components in the shop. And just resigns himself to regular cleaning and swapping to separate clothing before leaving the workshop.

Lastly, specialized machined alloy components. Actofive is the bike brand that drives Simon Metzner’s passion. And from that we get full-suspension Actofive mountain bike frames, cranksets & chainrings.

But he does plenty of contract manufacturing too. There’s certainly a bit of crossover in the bike industry – things like bashguards, top caps, and even some more advanced elements like rocker links & seatstays for other bike companies. But there’s plenty of other industrial machining, too. Simon explained that he spends the vast majority of his development and production time on the Actofive mountain bike side of things, but still more than three-quarters of his profit comes from contract machining.

Signature X cranksets were a big shift in making Actofive components more affordable, from just under 400€.. or half the cost of the original hollow Signature cranks.

Actofive direct mount chainrings add 120-150€ on top of that.

The rocker link on the I-Train is another great example of Actofive’s creative 2D manufacturing. Like most of their MTB components, it is made by simply matching two halves (from both sides) that are then joined together with a simple keyed interface and a single bolt for simple strength.

MTB frames start from 6000€ for the simpler I-Train frame set. A P-Train will set you back at least 7000€.

Interestingly, one way to get a hold of an Actofive mountain bike frame for a bit cheaper might be to lay your hands on a show demo. With Bespoked on the horizon, Actofive is offering deals in their online shop on previous versions of the I-Train that were already shown. And they are even offering the custom mk2 I-Train bike in advance, that will be on display in the Dresden Airport show over the weekend.

Of course, one of the cool benefits of an all-machined-alloy mountain bike (or components) is the ability for some flashy anodized finishes. Actofive has a partner manage their eye-catching colors, but they can even do some fun stuff with two-done finishes one side to the other.

I especially like the half blue + half silver race bike of Czech enduro World Cup racer y Vojta Bláha/DVO who showed off his bike to us for the DVO Prime launch earlier this summer.

OK, so here’s a real rare sneak peek inside an Actofive…

This red/orange I-Train front triangle is manufactured in 2 halves with a clamshell design. By machining each side individually, Actofive can creates the exact smooth outer shape that they want for the bike, but can vary thicknesses throughout various sections of the frame, much like you find with butted tubing.

But in reality, the inside of the I-Train is much more complex that that, featuring a series of reinforcing webs that vary the tube wall thickness much more than could be achieved by any tube-to-tube style construction.

And then the real secret comes with the mechanically overlapping finger joint from one side of the frame to the next. This greatly increases the surface contact area between the two halves, resulting in a strong bond when the frame is assembled with adhesive. And it also reinforces the joint at the top and bottom edges of the frame, protecting it against impact with rocks or other obstacles.

One thing I really love about Actofive’s bikes is how you can see the machining marks that show how the CNC tooling cuts back and forth into the aluminum billet. But of course, since they machine the inside of the frame just as much as the outside, our Actofive factory tour also gave us an up-close glimpse at how those tool paths are even visible inside of the frame.

Like on the inside of this I-Train’s headtube.

That was pretty much it for our Actofive factory tour. We got to watch some Signature X cranksets be machined – 60 crank arms at a time in that batch. And Simon revealed us a bit of what was coming soon this year. Think UDH compatibility across all frames, of course, including the ability to retrofit all of the frames they had previously produced. And these newly machined, open-back seatstays that replaced the I-Train’s original welded tubing stays.

Plus, there’s even more that we will see over the coming seeking with more next-gen P-Train & I-Train updates.

Stay tuned for that!

And with that, we’ll leave you with Actofive ‘After Dark’.

Much of Actofive’s CNC-machining processes take 8 hours or more to complete. So Simon tries to schedule it so that he can set up a machining task at the end of his workday, to run overnight. And he’ll often even reducing tool speeds a bit to ensure less chance of any trouble when the machines are left to work on their own.

Actofive has a webcam in the machining room so Simon can dial-in to keep tabs on progress – whether he’s upstairs working at his desk on another project, or back home for the night.

And while the lights go out in the human side of the Actofive workshop, the light often stays on all night as the CNC robot chugs away, machining mountain bikes through the lonely night.

Actofive.com