Bonding different materials on bicycle frames

Field Cycles was born of a desire to bring back authentic handmade craftsmanship to the world of bike making. In the beginning, Harrison and his team focused mainly on crafting bike frames made entirely out of stainless steel. To bond parts of the frame together, they would use brazing, a process whereby two metals are joined together by melting bronze around them. This process is so old that even the ancient Egyptians were doing it.

In more recent years, however, Harrison has looked to use other materials for his frames than just steel. These vary from other metals to composite materials such as carbon fibre. This all came from the realisation that his bikes may be better served, and also more unique, by trying out other materials in his frames.

A new bonding solution

However, this desire to blend frame materials meant that a new bonding solution was required. Carbon fibre, for example, is incompatible with brazing - it generates too much heat and damages the substrate. This challenge led Harrison to contact several adhesive companies.

"I reached out to a few different adhesive manufacturers, including some of the big ones," he recalls. "But the way that Permabond's technical service team dealt with me was just outstanding. From day one, they treated me as if I were a big company, even though they knew that I wasn't. Other companies basically just ignored me."

In this specific case, the adhesive application was bonding lugs made out of carbon fibre to a titanium frame. A suitable solution was soon suggested - Permabond ET5428. This highly tough, two-part epoxy adhesive offers fantastic adhesion on composite materials. Harrison tested the adhesive and found it to be perfect for the job at hand, and production of the bike began soon thereafter. Handmade, bespoke craftsmanship and design nevertheless takes time, and from Permabond's first contact at the end of 2022 to now being able to showcase the bike, the company has supported where it can every step of the way.

Having made the transition to mixed-material frames, Harrison is happy with what he's achieved. "There's no one else building bikes quite the way I do," he says. "Having a mix of materials and tech in one frame is quite rare. Normally, one material is used throughout the entire bike. Visually it's also quite different due to the different colours and materials."

A core benefit in combining materials lies in the ability to build in rigidity where it's needed, and more flexibility where it isn't. It's also good for lightweighting - especially in the case of carbon fibre.

Looking to the future, Field Cycles isn't in any rush to become the next Halfords. With customers becoming ever more environmentally and carbon-conscious and looking to buy from more traditional, 'slow' sources, the company is in a great position to leverage its natural advantage here. The focus will continue to be on making things locally with great care, precision and craftsmanship.