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HOLISTIC SUSPENSION – CHAPTER 4 -THE CROWN

The crown of a fork has to take up all riding and braking induced loads, transmit them to the steerer tube and ultimately the frame. It also has to follow your steering input as accurately as possible. All that is handled by a carefully shaped piece of aluminum. The crown of the F 535 ONE looks completely different to all the other fork crowns on the market. The reason to this is not only the design process, but also a different production method. Check out how the crown comes alive.

The forging

At the beginning there is a round alloy bar. A bending machine gives the solid bar the basic form. The forging machine applies a force of 800 t to form the rough shape of a F 535 ONE crown. During that process the temperature of alloy rises to approximately 550° C.

What comes out of the forging machine has got the rough shape of the crown. But it comes with a thick flash, excess metal which is squeezed out of the cavities and has to be removed. Two sets of specially made tools are used to remove the flash. In a first step the gross of the flash is cut off. The second trimming removes all but a small bit of the flash.

To make the raw part ready for the next work steps, the remaining bit of the flash is sanded by hand, leaving perfectly smooth surface. To remove all sharp edges and to create an uniform surface, the raw crown is then tumbled. Tumbling takes place in a big tank filled with small ceramic grains. The whole tank vibrates at a high frequency, leaving a smooth and uniform part finish.

CNC machining

What makes the production of the crown completely different to all the other forks is the next step. After forging the rough shape, the crown is taken to a five axis CNC machine where the whole upper section of the F 535 ONE crown is 3D machined. This ensures a precision fit of the covers and seals and it let us manage precisely the strength to weight ratio. No one else does this in the bike industry, this is where high tech produces high precision and allows a unique design for the F 535 ONE.

Three different machines and multiple fixations are required to machine all interface sections of a F 535 ONE crown. The first step is to machine the stanchion and steerer seats.

The second step is where all the 3D processing takes place. The whole upper area including the through holes from the steerer to the stanchion bore are made on a high speed five axis machine.

The final operation is the drilling of the cable guide holes needed for the remote version of the F 535 ONE fork.

Finalization

After all the machined interface areas have been covered, the crown is ready to receive a powder coated base layer. This layer protects the aluminum surface and evens all imperfections in the surface for a clean and durable finish.

Part to protect the base layer, part for stealthy looks, the F 535 ONE comes with a flat black powder coat finish.

Stanchions and steerer are pressed in, the crown unit is ready to ride. What follows is the assembly process with the addition of damping and spring top caps, the adjuster as well as the aluminum covers complete with custom made alloy bolts.

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