Engineering Takeover: How many arms should a folding ebike fork really have?
Interview with Adam, the lead designer on FLIT’s front fork project
Space is a precious commodity for anyone in search of the perfect folding ebike. Whether it’s for commuting, storing at home, or taking on public transport, the size of a folded bike is all important. When designing the FLIT M2, our engineers were well aware of this and from the outset had a clear goal to develop a smaller, lighter and more refined ebike to succeed the FLIT-16.
One of the key elements in achieving this feat was the implementation of a single-arm fork. Removing one of the arms of the M2’s front fork allows the front wheel to sit much closer to the rear wheel when folded, thereby reducing width. This departure from conventional fork designs marked a significant step in developing a more compact and practical ebike, making it a more attractive choice for commuters and urban explorers alike.
Many parts of the M2, including the fork, wheel, and handlebars, must move and interlock harmoniously to create a smooth fold. The single-arm fork on the FLIT M2 significantly reduced the width of the bike when folded and resulted in a much neater form. This enhanced portability when carrying and rolling without compromising the easy fold or ride quality.
The single arm fork allowed the team to take additional steps to increase the functionality and usability of the M2.
“One of the significant changes this allowed us to implement, was the new retaining feature which is built directly into the front hub. The new snap ring style retainer aligns directly with a pin mounted on the rear swing arm to ‘CLICK’ into place with a little push.”Adam, lead designer on the fork project.
The other major upgrade from the FLIT-16 which made the single arm fork desirable is the hydraulic disc brakes on the M2. “Disc brakes require a mount closer to the hub on the non-drive side of the bike, this corresponded to the arm which ended up on the outside of the fold so we could improve the components and keep the narrow design.” Adam explained.
Designing the fork was about balancing decisions which improved the size and functionality whilst also creating a fork which aligned visually with the rest of the bike. The initial design phase involved numerous sketches and brainstorming sessions to envision how the single-arm fork would fit into the overall bike design. “You have to remember you’re not designing one element in isolation but part of something much bigger,” Adam emphasised.
Moving from sketches to reality, the team transitioned to computer-aided design (CAD) and created 3D-printed prototypes to explore how the final product would come together. It was soon obvious that CNC machining was the ideal manufacturing process for creating the fork. This manufacturing method involves removing material from a solid block of aluminium, striking a balance between lightweight construction and robust strength.
The team went through many iterations to ensure they got it just right, resulting in a refined, elegant solution that seamlessly combined form and function. At each stage, the fork was put through rigorous testing which simulated the use cases that the M2 would go through in real-world use. This testing went beyond the required industry standards to ensure a safe and reliable product and accounted for the M2’s unusual design.
In the end, the single-arm fork design of the M2 folding ebike was more than just a practical innovation; it was a testament to the team’s commitment to enhancing the folding ebike experience. While single-arm forks were not a new concept – they have particularly been used for decades on mountain bikes – the team saw this as an opportunity to take things a step further. A smaller fold, a lighter fork, and increased functionality make the M2 a joy to ride, fold and roll anywhere you go.