About FiftyOne

FiftyOne began in 2016 when former international rider Aidan Duff set out to put fit and feel back at the top of high-end bike design. The brief was clear: pair bespoke carbon craft with geometry that serves the person on the bike, not a spreadsheet. We started in Dublin with hand-built custom road frames - our halo, and still our benchmark. That same craft now drives our factory platforms for gravel and road, the Assassin and Sika, different paths, same standards. Every frame carries the same signatures: clean routing, tight tolerances, carbon placed with purpose, paint with intent, and a ride that feels right from the first corner.

Cycling is a unique sport, one in which teams compete but individuals win and lose. Every team has its designated leader, and the only way for the team to win is for every other member to work in service of the one. So, when race numbers are handed out, the leader’s dossard always ends in “1”, 11, 21, 31 - a subtle sign that sets them apart.

For over six decades of Tour de France history, dossard number 1, worn by the defending champion, was the most prized, and the most successful. Then, four times in nine years, the Tour de France was won by the rider wearing 51. And these were no ordinary Tours.

Eddy Merckx rode to his first win, in his first Tour, in 1969. Merckx was absent in 1973 when outsider Luis Ocaña crushed the competition in both the mountains and the time trials, winning by over 15 minutes. Bernard Thévenet effectively ended the Merckx era, and took the Tour, with a dramatic attack on the Col d’Izoard on Bastille Day 1975. In 1978 a new era arrived as Bernard Hinault took the first of what would become five yellow jerseys. Four of the greatest stories, and the greatest champions, in Tour history.

Ever since, race number 51 has carried a special mystique that sets its bearer apart, a quiet way for organisers to honour a rider with something extra. That mystique is alive today: in 2025, Pauline Ferrand-Prévot won the Tour de France Femmes wearing dossard 51. We took that number as our name because the principle is the same as FiftyOne: Built with the individual in mind, by an obsessive, disciplined, and hard-working team.

At FiftyOne, we believe that every customer is unique. Our priority is to create the best possible riding experience for you, one that feels calm, confident, and tailored to your specific needs, because we understand that this varies from one rider to another.

To achieve this, we focus on two key elements. First is craftsmanship: we pay meticulous attention to geometry and use high-quality carbon, selecting and placing materials for optimal responsiveness without sacrificing comfort. Second, we prioritise understanding your needs: we listen to you, assess your fit and riding style, and learn what you truly want from a bike. When craftsmanship and understanding come together, the result is a bike that feels perfect the moment you start pedaling.

These values are at the heart of everything we create. Our exceptional custom builds represent the pinnacle of our work, featuring personalised geometry, fit, and finish. Our Assassin gravel frame carries this same ethos into a factory platform, equipped with flip chips in the front and rear that allow you to adjust the ride to suit various terrains and styles. Our Sika road platform offers a balanced, confident feel for modern road riding, providing the comfort and refinement needed for long rides.

We collaborate with you to ensure that the build is just right, including the aesthetics. Our custom paint process is well-guided, involving thoughtful choices and clear direction to help you explore options until you find a design you’ll love every time you hit the road.

At FiftyOne, 'Custom' means more than just fitting; for a bike you'll truly cherish, we ensure it’s a personal experience.