Carbon Fiber Bicycle Fork

How to make a carbon fiber bicycle fork

Materials

carbon fiber mat
epoxy
404 High density adhesive filler
foam
MDF
vacuum bag materials
Trash bags

Tools

CNC router
vacuum pump
drill
ban saw
drill press
drill bits
tap and die set
dremel
drill bits

Choose Your Setup

Before you start to design your fork you will need to get your hub, rim, decide on what type of brake you want, and the size of your head tube. The fork I made is going to be for a front wheel drive bicycle so I went with a NuVinci hub, 20" wheel, disk brake, and 1 1/8 headset.

Design and Cut Out the Wheel Mounts

the wheel mounts need to be strong enough to hold the wheel to the fork during high speed braking. The mounts I will use three bolts for mounting. The left mount has a disk brake attachment and the right mount has an attachment for a chain tensioner.

Fork Jig

When assembling the fork you will need the help of a jig to get the wheel mounts in the correct places. When building the jig you will need MDF threaded rod, nuts and washers. Place a fork on a flat table with the steering tube level with the table. measure the distance form the steering tube to the wheel mounts, the distance from the table to the wheel mounts and the diameter of the steering tube. In drawing software plot all the points to establish the mounting locations. The software I used is Autodesk Inventor. Once the three points are in the software then you can design your jig around them.

Design the Fork

using the same points as the jig design the fork.

Design the Female Molds

You will need a top and bottom female mold that splits in the center of your fork.

Cut Out the Molds on the CNC

Epoxy Sand and Wax the Molds

Vacuum Bag the Carbon Fiber

lay down a trash bag
place mastic tape around your mold.
cut out the vacuum bag materials.
wet out your mold with epoxy
wet out your carbon fiber with epoxy
lay in two layers of wet carbon fiber
vacuum bag the mold overnight

Remove the Part From the Mold and Trim the Edges

to trim the edges use a band saw and sand paper.

Fill With Thickened Epoxy

I wanted to make sure this part was very strong so I filled most of the fork with thickened epoxy.
now is the time to glue in the steering tube to one half of the fork
wax another pipe and glue it to the other half
once dry pop off the waxed pipe and it will leave space for when you glue the two sides together.
once dry sand the thickened epoxy

Glue Both Sides Together

use electrical tape to hold both sides together while they dry.
after your fork is dry sand it smooth.

Drill Holes for Your Wheel Mounts

pick out the bolts you want to use find the tap and drill bit that goes with it
place the fork in your jig
clamp your wheel mounts to the outside of the fork
drill the bolt holes
don't tap the holes yet

Wrap the Perimeter in Carbon Fiber

wet out the carbon fiber
wrap the perimeter with a strip of carbon fiber
vacuum bag the fork
once dry use a dremel and open the holes on the inside of the fork don't drill all the way through
tap the holes