This year’s buzz: Gas Forks

Gas forks hit the mainstream with Kawasaki's 2016 ZX-10R, but what’s the big fuss?

Every few years, there has to be some new bike tech for us to get excited about. It's been the same since forever – your grandad was every bit as stoked when he saw the first foot gear-change as your dad was when they came out with disc brakes, as you were with USD forks and your kids about launch control. That's the nature of the beast: competitive firms have to try and get the march on everyone else to make their bike the one you go for.

Some of these leaps forward are genuinely great, and have changed biking. Some – not so much. So what category are gas forks in? A game-changer like aluminium frames, fuel injection or ABS? Or a bit of a small, incremental improvement, like Big Piston Forks or ride-by-wire fuel injection? Well, from a technical point of view, there's no doubt that they give a far better damping setup than conventional cartridge forks. The fact they've been using them on MotoGP and WSB/BSB machines for a while now is a bit of a clue there of course. The main external sign is the little cylinder next to the brake calipers. This contains pressurised nitrogen gas, behind a moving piston that keeps nitrogen on one side (the top part of the cylinder) and damping oil in the bottom part of the cylinder. It’s rather like a piggyback rear shock, which has been commonplace for years now.

The trick with the gas cylinder is that this gives a reservoir into which the damping oil can flow into and out of. So when the fork compresses, it pushes some of the oil out the bottom of the fork casting, through damping channels, into the cylinder, pushing the floating piston up a little against the nitrogen pressure. When the fork extends (rebound), some oil flows back into the main fork body, again, through (different) damping channels. Now, if you have adjusting components in these channels, you can adjust how the oil flow is restricted when moving from the main fork to the gas cylinder, and vice versa. That's part of what gives the damping force, and this simpler system allows much finer, more precise adjustment. As a byproduct, the gas cylinder helps keep the damping oil cooler too.

Would a BFF fork make a big difference to the performance of your naked 500cc twin commuter on a wet Wednesday morning on the A50? Well, probably not. And even on a Supersports bike, for most people riding on the road, the extra performance wouldn’t transform their ride. But as the technology on the BFF units trickles down, it will no doubt help make another incremental improvement in generic bike suspension performance.

So why are we seeing these forks now? Well the answer is there at the start. These forks are used on the very best race bikes. Kawasaki wants to sell more of its Supersport ZX-10R. So it's fitted these super-high-performing forks (and the 2017 Suzuki GSX-R1000 is getting them too), to get us all excited about flashy new technology.

And, to be fair, it’s working a treat.

Biog: Alan Dowds (Dowdsy)