Three years ago, I came up with the idea to make my own custom bike. For the first year, I was skeptical if I should buy a new bike rather than taking the harder path of making it myself. Despite the risks of failure, I still encouraged myself to go with the more difficult option and to spice things up I wanted to make a full-suspension frame.
I spent a lot of time on the internet learning about frame building and thanks to websites like Pinkbike I got a lot of information that I wouldn't have otherwise. All the forums and videos were very helpful at the beginning. Next, I started making frame geometry, initially on paper and then soon after on a computer where I continued 3D modeling using Autodesk Inventor. I was also using the Demo version of Linkage X3. Although you don't have access to some of the program functions it's still helpful. This process of learning, planning, designing took me about 18 months because I didn’t want to overlook anything I could later regret.
For me, the frame is the heart of the bike, the geometry really needs to suit you well. This is why I think frames with custom geometry are just on another level.
For the material, I choose 4130 Chromoly steel because it is suitable for beginners to work with and more important its ride quality.
The jig I built is from 40x40 mm Aluminium extrusions. It's kind of affordable and good for beginners. With the lathe, I also made a couple of aluminium holders, mounted on 90° joints, for holding the bottom bracket, seat tube and head tube. What I really like about it, is that you can easily change it and make whatever kind of bike you want.
For tube mitering I was using Bosch hole saws, mounted on a milling machine. Because everything was held together securely, without any movement, the fit between tubes was tight. I was relieved when I saw on the 3D model that I am not going to have to bend any of the tubes because there is a lot required to master bending those tubes. For the next build, I will make sure to try some bending to learn that skill.
Mitering hole for the main pivot.
SRAM DUB PressFit bottom bracket bearings as pivot bearings.
Next, I was thinking about what kind of linkage should I make. Given that this was my first frame I didn't want to make it too complicated, for this reason, the answer was simple. A single pivot.
Another question I had to ask was what kind of bearings should I use for the swing arm? I decided to go with bottom bracket bearings, more specifically with SRAM DUB PressFit bottom bracket bearings, and I am glad I made this decision.
They are strong, well-sealed, and I never had any problems. Also one of the unique parts of the bike is the dropouts. They are made out of 7075 Aluminum. I can easily make another pair of them a couple of millimeters longer if I ever wanted in the future.
One of the stages of making dropouts on a milling machine.
I didn't have a lot of experience welding TIG before because I started learning it like 1-2 months before it was time to weld frame. I spent a lot of time cleaning tubes before welding because it makes big difference. Tight connections between tubes are also important. Not the best-looking welds, but for the first frame I built, I am very happy with how it turned out. Because the frame jig was straight I didn't have to align the frame after welding.
I am very satisfied with how the finished product looks, and more importantly how it rides. After testing it now for quite some time I can say that the ride is impressive.