How Bike Frames Are Made in 5 Steps

how bike frames are made
how bike frames are made

Ever wondered how bike frames are made?

Bicycles are one of the most popular modes of transportation around the world. In fact, there are 1 billion bicycles that stroll across the globe, outnumbering cars by two to one.

Especially with the current pandemic situation, an increased momentum for cycling has surfaced, which lifts bike sales sky high and give long-time biking advocates new hope to look forward to.

There are plenty of reasons why this biking popularity is taking place. During lockdowns, the number of motor vehicles on the road took a plunge.

This results in the increased number of people who turns to using bikes as their major means of transportation, moving speedily and safely through once congested streets

Another reason why cycling has attracted more people is because of nationwide gym closures. Gym Goers found an alternative fitness routine through cycling, and this also made way for the rise of more biking communities.

This sudden fad in biking gave bike manufacturers more demands to meet in producing bikes to cater to commuters all over the world. In line with that, let’s find out how the most important part of a bike is manufactured, the bike frame.

Table of Contents

The Raw Materials

The most common frame design for a bicycle is based on the safety bicycle,, and comprises of two triangles: a primary triangle and a paired back triangle. This is called diamond frame.

The diamond-shaped frame is a vital part of a bike because it links all the other components to form this eco-saving mode of transport. The bike frame provides strength and rigidity to the bicycle. It also determines how one can handle the direction of the bicycle.

The frame consists of front and rear triangles: the front triangle forming the quadrilateral of four tubes while the rear triangle consists of the chainstays, seat stays, and rear-wheel dropouts.

Of course, the beginning of bike frames is considered to be outdated. The first bike frames were made up of steel and alloy steel that is strong but relatively heavy.

Flash forward to the 1970s, frame material has greatly improved to increase strength, rigidity, lightness, and durability.

During this era, a new generation of bike frames used more versatile alloy steels that could be welded mechanically, which results in the increased availability of light and inexpensive frames.

In the 1980s, lightweight aluminum frames became the favored material when constructing a bike frame. Although more lightweight, it also comes with a price: aluminum may fatigue within three to five years.

On the other hand, heavier metals like steel and titanium have a life-expectancy spanning decades.

Hope was shed during the 1990s when bike manufacturers used lighter and stronger frames made of composites of structural fibers such as carbon. This material is anisotropic, which makes it strongest along an axis of the fibers.

By using carbon, it can be shaped into single-piece frames, providing strength where needed.

The Manufacturing Process

1. The Manufacturing Process

When creating world-class bike frames, it should start with premium-grade raw materials. Here in Cyclenatics, we only use top-quality solid blocks of steel. These blocks are then pierced and drawn into tubes through several stages.

These steel tubes can be manipulated to increase and decrease the weight by altering the thickness of the tube walls. This process is called butting. 

The differences in wall thickness also helps improve the resiliency of the frame.

There are 4 kinds of butted tubes depending on the placement of the thickened ends: 

  1. Single butted where one end is thicker;
  2. Double-butted where both ends are thicker than the center;
  3. Triple-butted where either end have different thickness, and;
  4. Quad-butted, which is similar to a triple, but with the center thinning towards the middle.

These tubes are then assembled into a frame by either hand-brazing or welding by a machine, which is more labor-intensive, therefore, may cost more.

Tubes may be joined by using strong industrial glue or plastic binders, then final adjustments are made by skilled bicycle builders.

2. Tailoring the tubes

The metal composites are softened by heating and hollowing out the insides to form “hollows” or “blooms.” These are heated again, submersed in acid to remove scales, and lubricated. 

Then, tubes will proceed to a machine where they will continuously be measured, cut, and precisely mitered according to the appropriate dimensions. Next, the hollows are fitted over a mandrel or a shaft attached to a drawbench. 

To achieve the proper and exact gauge, the hollow needs to pass through dies that stretches them into thinner and longer tubes. This process is called a cold drawing.

The tubes can be shaped into a variety of lengths and designs depending on the configuration. The taper-gauge fork blades will pass through more than a dozen operations to achieve the correct strength, weight, and resilience.

3. Brazing, welding, and gluing

There are three ways to connect a tube to another to form a joint: brazing, welding, or gluing. 

Brazing is essentially welding two tubes at a temperature of about 1600°F or lower. Gas burners are arranged around the lugs evenly, which are heated, forming a white flux that melts and cleans the surface, preparing it for brazing.

The brazing filler is typically brass or silver, which melts at lower temperatures than the tubes being joined. The filler is applied, and as it melts, it goes around the joint, sealing it.

Welding is the joining of two tubes using a hotter temperature, up to 2500°F to 2700°F. Due to a higher temperature, the metal in the two tubes melts together. They become a part of each other as the molten metal cools down and hardens. 

Gluing is the process of joining two tubes without the use of extreme heat. Industrial grade glue is applied at the end of the tubes and is adhered together to form a frame. 

4. Aligning and cleaning

While the frame is still hot and malleable, it will be placed into jigs and checked for proper alignment. If adjustment is needed, a worker will manually correct and align the tubes according to the proper alignment. 

The excess brazing metals are cleaned off in two ways:

  • By pickling the frame in acid solutions
  • By washing and grinding the brazing metals until it is smooth

After the metals have cooled, further precision alignments are made, which are typically done with the assistance of laser-emitting computers. 

5. Finishing

Cooled off frames will now proceed to paint for protection, as well as to create a more finished look. 

The frame is first painted with an undercoat and then painted with colored enamel. Paint may be applied by hand-spraying or bypassing the frames in automatic electrostatic spraying rooms

Finally, if the design requires it, transfers and lacquer are applied to the frame. Chrome plating is also available on components such as the fork blades.

Conclusion

Getting a new bike is considered to be an investment, so it is essential to get a hold of a durable and long-lasting bike frame. Here at Cyclenatics, our goal is to give you premium-grade bike frames and other bike components at an affordable price. 

If you have manufacturing concerns, please reach out to our online support team, and we will handle them.

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