INTERCONNECTION

The purpose of interconnection is to allow the stiffness of the suspension in the pitching direction to be much lower than the stiffness in the bounce direction - or in other words, the stiffness when the wheels move vertically but in opposite directions to each other is lower than when the wheels move up and down together.

For practical reasons, the bounce stiffness of a bicycle suspension must be high to preserve ground clearance and to maintain the height of the saddle above ground for ease of mounting. If the bounce stiffness is too low, the height of the saddle of the bike without rider must be very high so that when the rider's weight is added, the suspension sinks to the correct level making it difficult to mount in the first place.

The behaviour of interconnected suspension is similar to a railway bogie – the closer the springs are to each other, the lower the pitching stiffness, while the bounce stiffness remains the same.

For cyclists, this behaviour will be familiar. Consider what happens when a cyclist traverses a stretch of bumpy ground. The cyclist lifts their weight off the saddle and onto the pedals in anticipation of hitting the bumps. With the handle bars held quite loosely, the rider allows the bicycle to ride over the bumps in much the same way as would a bogie, before transferring weight back onto the saddle and resuming pedalling, and therein lies an important observation...it is very difficult to pedal whilst travelling over bumpy ground. The act of pedalling and negotiating bumps are almost mutually exclusive.

Interconnected suspension reproduces the action of the bogie without the need for the rider to transfer weight off the saddle, thereby making it possible keep pedalling whilst travelling over bumpy terrain, significantly reducing rider fatigue in the process.