Big Piston Forks - What are They?
Big Piston Forks (BPF) – what are they? When the oil flows around a conventional 'cartridge' fork under compression or rebound it enters a separate chamber through a sub-piston to flow back to the opposite side of the piston from where it started.Big Piston Forks simply do away with this extra chamber and instead the oil flows through a bigger piston (hence the name) and a single chamber that is located between the fork leg and slider – the whole fork leg becomes a cartridge instead of containing a separate cartridge unit.
The benefits of the Big Piston Forks design are a lighter fork with fewer components and also the bigger piston given more accurate damping as the oil's flow is better controlled.
