Bicycle Front Rack

I needed a small front rack on my gravel bike to avoid the handlebar bag from rubbing in the front wheel and to carry some lightweight groceries. Since each bike/fork has its own bolt pattern, I had to make a custom one for my bike.

The build is relatively straightforward but some metalworking experience is preferred. I'm not the most experienced metalworker but during pandemic and with more time at home I decided to learn stick welding and after many burnt rods I decided to make something useful other than metal scrap to "step up" my welding skills.

The materials/tools you will (probably) need to build something like what I did:

• Small tubing (I used 10 mm with ~1.2 mm wall thickness);
• Smooth flat profile;
• Tube bender (the same size of the selected tubing);
• Weld inverter/Stick welder and welding rods (308 L);
• Drill press and drill bits;
• Pipe cutter;
• Square and measuring tools (rulers, verniers, etc.)
• Files (of the same diameter of the tubing);
• Angle grinder (optional);

I went with a simple rectangular shape. I measured the width of my fork legs at the bolt locations and fixed that as my reference. The height was a little bit bigger but this is entirely subjective to each fork/bicycle/person.

What is not relative is the way you measure it. You need to know the bending radius of your bending tool so that you end up with precise dimensions. If you want a certain length (width or height) to have a total X mm/inch you need to subtract two times the curvature radius of your bending tool and the diameter of the tubing. With that you have the total length of the "non-bent" sections and from that you can define the starting points and, by considering the perimeter of the bend (a fraction of 2 x π x R), you can cut the tube to the total desired length. You can also pre-determine and mark all the points at which the bends will occur. It may take some time and thinking in a first approach but then is quite straightforward.

I fixed the bending tool on a vise and made a mark to help keep the bends in the same plane. I created a guiding line in the tube placing it against something in a fixed position and with a marker on a flat table. Take your time to bend the tube, particularly stainless has it is quite hard to bend. Make sure that your bender is also adequate to the material you want.

While bending keep an eye on squareness, even if you follow the angle marks on the tube bender those will not match to what you want. If you have marked everything correctly, the two extremities of the tube will align perfectly. I must admit that it is quite satisfying seeing that happen.

After that you can weld the two extremities. I used a stick welder because that was all I had (argon is expensive where I live). With adequate electrodes and amperage you can make it work even tough it isn't a clean weld (use a stainless steel wire brush to clean the welds). Make sure to wear eye protection as the stainless steel slag likes to jump everywhere.

With everything welded, I cut two tubes and notched them with a file to match the outside diameter of the tubes. A wood block is helpful to keep the tube in a upwards position. I also cut a U shaped tube to place it in one extremity of the rack and to avoid things falling towards the bicycle headtube. With everything tacked in place, it is time to patiently weld everything trying to change the welding pattern to avoid distortion.

The last piece of the top part was the small flat profile with three holes to provide some adjustment when fixing it to the fork. These were designed for M5 bolts and to be fixed with washers and nuts (no taps needed). This plate was also stamped with my name and year with a letter punch jig I previously published here.

After that I decided to smooth all visible welds just for aesthetics.

With that flat profile welded to the top part I transferred the bolt pattern to a longer piece of flat profile and bent it with an hammer in the vise. The edges were also smoothened with an angle grinder. This piece will provide the top attachment to the fork.

With the top part attached to the fork it was just a matter of cutting the side mounts/tubes to de desired length. I decided to have the rack matching the slope of the frame for aesthetic purposes and to try to avoid things from falling off the bicycle.

With the vise, I just created a flat surface to provide an attachment point through a bolt by crushing the tubing. In my case I had to bend the tubes close to these flat surfaces in advance because the tube would touch the fork legs. Alternatively I could increase the size of the flat surface to avoid the tubing but that is not aesthetically pleasing for me. I find that this solution of crushing the tubing works quite well and does not affect tube resistance significantly.

LastIy, I tacked everything in place to avoid as much distortion as possible (which is impossible to avoid).