Full on the milling machine: Home visit & bike check at CNC specialist Actofive
Max Fuchs
· 19.12.2024
Rough industrial park ambience, steel-grey sky and faded graffiti on the walls - I couldn't have imagined a better setting for an East German bike manufacturer. As I look around the courtyard and the autumn chill is already creeping up my trouser legs, a heavy fire door flies open next to me. "Hi, are you Max?" Simon Metzner - sporty build, casual jeans outfit, three-day beard - extends his hand towards me. He is the founder of the Actofive brand, the mastermind behind the CNC-milled mountain bikes from Dresden. The fact that the mechanical engineer has a skilful knack for mountain bikes first made the rounds in 2020. Back then, he launched the first trail bike with a high-pivot rear triangle. Actofive was thus the pioneer of a trend that would primarily affect the enduro segment.
In the meantime, Metzner has led me into his hall compartment. Bare frames hang over a metre-long workbench. Milled parts reminiscent of seat struts spill out of the Euro boxes on the floor next to me. And massive aluminium blocks are stacked under a metal staircase leading to a small gallery with an office. The 130 square metres seem like the wet dream of every mechanical engineering student. And in the centre of this technical oasis stands the I-Train - Metzner's latest creation. Incidentally, the engineering graduate took the name from a shuttle bus at Helsinki airport: "I have a personal connection to Helsinki, and the city inspired me during development." The key data of the bike: 140 millimetres of suspension travel, a four-bar rear triangle and 29er wheels. Sounds like an ordinary trail bike - at least as far as the facts are concerned.
But: there are plenty of eye-catchers on this bike. It starts with the frame. The shiny metallic surfaces feature the characteristic milling grooves of Metzner's Portatec Basic. For the main frame, the 3-axis portal milling machine eats its way through a 94.5-kilo aluminium blank (7075-T6) for twelve hours. The resulting half-shells are then glued together. The chain and seat stays come from the same milling table, but are hollow-cut from one piece. Including the two-piece milled rocker link and the bearings, the milled work of art weighs 3300 grams. This is not a peak value, but it ensures that the frame can also withstand worst-case scenarios.
Actofive I-Train: the true all-rounder
And yet the degree of innovation of the CNC chassis is limited. Competitors such as Pole have been using this manufacturing process for years. The true strength of the I-Train lies in the detail. It wasn't supposed to be another trail bike for everything and nothing," says Metzner. Rather, the motto for the development was to create optimum customisability for the widest possible range of uses. The 11,500 euro bike is therefore not only compatible with 140 mm forks, but also covers the entire suspension travel range from 120 to 150 millimetres. Thanks to modular dropouts, the I-Train can also be ridden with a small 27.5-inch rear wheel! And of course, an angled headset is also on board. There is also a flip chip in the lower shock mount for fine-tuning the bottom bracket height.
The facts about the Actofive I-Train
- Price: 11 500 euros (frame 5990 euros)
- Fork / Shock: Rockshox Pike Ultimate / Canecreek DBAIR IL
- Gears / range: Sram XX Eagle Transmission / 520 %
- Brakes: Magura MT7 Pro
- Wheels: Duke carbon rims, Nonplus hubs (hand-built by Litewolf)
- Tyres: Schwalbe Nobby Nic Soft / Racing Ray Superground Speed; 29x2.40
- dropper post / stroke: Bike Yoke Divine / 160 mm
- Total weight: 13 kg without pedals
- Guarantee: for life
- Max. System weight: 120 kg
- Special features: CNC-machined frame, variable main pivot point, angled headset, damper flip chip
But that's still not enough. When it comes to kinematics, the Dresden mastermind has created a world first: the first variable main pivot point. Its height can be adjusted in four stages via a flipchip, which changes the anti-squat behaviour of the rear triangle. The higher the pivot point, the smoother the rear end remains under chain tension. The disadvantage: The higher the pivot point, the more the rear triangle elongates during compression, which leads to increased pedal kickback. This is why Actofive only recommends the highest setting in combination with O-Chain systems, in order to decouple the suspension from the drive influences. In practice, the concept enables XC-level propulsion, an optimised wheel lift curve and minimal pedal kickback at the same time - if that doesn't get to the heart of the all-rounder concept of a trail bike.
More bikes from the CNC milling machine
The geometry from our BIKE test lab
Driving report: Actofive I-Train
We were able to test ride Metzner's sample bike during our visit to Dresden. Our setup: Frame size M, 29er wheels, a 140 mm fork and 130 millimetres of travel at the rear. The flip chip for the bottom bracket height and the angled headset (65 degrees) are both set to neutral. The adjustable pivot is in the second-highest position. In theory, this means good anti-squat values with medium pedal kickback. The test lap on Metzner's home trails confirms this. When you pedal, the rear suspension remains quite stable. However, in the second-lowest position there is no aha experience.
The pedal kickback is all the more noticeable. The riding position is super-compact due to the very steep seat angle - not for long tours on flat terrain, as this puts a lot of pressure on the hands. However, this position is ideal on steep climbs. Paired with medium-length chainstays, the I-Train impresses with excellent control on tricky climbs. The same applies to fast descents. Flat head angle, generous reach - the I-Train keeps its cool even at high speeds. The I-Train also deserves a big like when cornering fast.
Conclusion from Max Fuchs, BIKE test editor
At first glance, the I-Train didn't knock my socks off - I'd seen CNC-milled frames before. But the closer you look, the more Metzner's latest creation turns out to be a fascinating piece of engineering. The technical details make the I-Train a one-off that will make the hearts of tech nerds beat faster. It also impresses off-road.
Max Fuchs
Editor
