“I wouldn’t have asked you to come along for this if the shock isn’t as good as it is.” I’m Eddie Arnet and that was what RC told me while loading coffee, herbal tea, riding gear and cameras into the Isuzu Trooper. What Richard was talking about was the new 5th Element shock. Progressive suspension, the manufacturer of the new technology, had invited us out to ride their newest production example of the radical suspension.

The 5th Element shock was brainstormed by suspension guru and American Honda tech Charles Curnutt. Roy Turner had purchased the idea from Charles and licensed Progressive Suspension to manufacture it. Richard had already tested the shock with Charles Curnutt’s son sixmonths earlier. Richard liked what he had seen and was already sold on the technology. “You’re soon going to feel just how much potential this shock has,” added Richard. I nodded in agreement as we made our way through the desert and up the backside to Mountain High. Richard didn’t have to convince. I had understood and knew about the system for over four years and ever since I did a tech piece on the Curnutt shock for Motocross Action. In simplest terms the big news about the 5th Element shock is that it has self-generated position sensitivity.

The shocks that we are all riding now use a charged compensator chamber (reservoir). The compensator chamber allows the shock to be assembled so that the hydraulic damping circuits won?t be compromised by air bubbles. As the shock compresses and oil is forced through the damping orifices, the compressed fluid is pushed against the compensator piston. As the piston is pushed it increases the pressure within the compensator chamber. What Curnutt has done is to use the rise in compensator chamber pressure to automatically increase compression damping as the shock moves. By adjusting an external compensator chamber volume control and by chamber air pressure the rider can tune how far into the shaft travel that the shock reaches its compression threshold. (The point when a force against the shock is great enough to open the main compression valve.)

What this means on the trail is that the rider can tune exactly at what point they want the rear suspension to get harder. By adjusting how soon and how much of a compression wall the shock hits up against the rider can adjust at what point the shock moves on big hits. The advantage here is that the rear suspension rides level against the threshold and allows the bike to be sprinted without activating the rear suspension. Even though the shock doesn’t feel like it’s moving when you’re pedaling, it still absorbs small irregularities in the terrain. That’s because the suspension is working freely in the lighter damped, negative travel portion of the stroke.

Think of it as a shock lockout that automatically engages a third of the way into the shock’s travel. The bike absorbs small bumps in that first third of travel yet pedals firmly like a bike with the rear suspension locked out. Best yet, the rider doesn’t feel the suspension moving in the beginning of the shock stroke. All they feel is a solid pedaling bike that is more absorptive to small and large bumps than anything they’ve experienced in the past.

What Roy Turner did is to take the Curnutt technology and added adjustable high- and low-speed compression circuits. That gives the 5th Element its namesake five adjustments: 1) External rebound damping adjuster. 2) External compensator chamber air pressure adjustment. 3) External compensator chamber volume adjuster. 4) External hi-speed compression damping adjuster. 5) External low-speed compression damping adjuster. The 5th Element is just as applicable to downhill bikes as it is to cross-country bikes. Downhillers ride bikes that actually can be pedaled, and cross-country riders have supple damping on a bike that pedals like the lockout is engaged. Incredibly, the 5th Element has a third of the internal parts of a conventionally-damped shock. The October issue of MBA has the complete technical scoop on the inner workings of the Curnutt and 5th Dimension shocks.

So what’s the ride like? Roy Turner was quickly able to tune the six inch travel rear end of the Intense Uzzi SLX to pedal better than any other full suspension XC race bike on the market. After climbing 1500 feet to the top of Mountain High without power wasting suspension movement I was able to blast the downhill course on a supple, six inch travel bike. Amazing.

The Curnutt and 5th Element technology will be available to fit all types of downhill and cross-country rear suspension configurations. We expect the damping to soon be applied to forks as well. With both the front and rear suspension holding firm against the compression threshold it would redefine the current thinking on frame geometry and suspension travel. Just imagine riding an eight inch travel bike that pedals like a hardtail, turns like a slot car and glass coats the Kamikaze. To get a jump of the technology call Progressive Suspension at (760)948-4012
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