Mercury Wheels have been an under the radar brand for about ten years but they are hoping to burst onto the scene in a big way with their new mountain bike wheelsets that feature a mystery material called Fiber-X.
The American brand have incorporated a strip of the material in the middle of the rim and it is apparently two times as strong as carbon but also more ductile, solving the main two problems Mercury sees with carbon wheels - impact resistance and stiffness. All impacts on the wheels are channeled towards the strip and it is apparently able to absorb them far better than a normal carbon rim.
So what is the material? Well Mercury says that it "absorbs like Kevlar on steroids" and can resist a double impact of 120 joules but they flat out won't tell us what it is. We do know that it is a material that is widely available on the market but by keeping it a secret Mercury are hoping that they can stay one step ahead in the competitive world of wheel manufacturing.
The technology is currently only available in Mercury's X1 wheelset that are available as either an enduro or ebike version in 29" or 27.5". The enduro wheels have a 30mm inner width, 38mm outer width and 24mm depth. The wheels also use Mercury's own hubs that have a 6 pawl system with 3.5° of engagement. The wheels weigh 1,729 grams (29") and retail at $2,399USD for a pair.
More information here