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Suspension has been advancing as rapidly as it has been spreading. While the quirks have been mostly worked out of suspension, the technology will continue to advance, so you'll have to invest in it like a computer: buy based on what will meet your current needs.

The latest suspension forks make the bumps undetectable, are impossible to bottom out, and require nearly no maintenance. Rear suspension designs have the entire drive train suspended, making "pogo" a thing of the past. Prices are about the only thing that, sadly, hasn't changed much.

Elastomer Forks

Elastomer is bouncy ball material, and is great at absorbing bumps. Softer elastomers give more easily, dense elastomers take the big thumps, and if you mix them together, you've got a suspension fork that offers the best of both worlds. The Manitou 4 (US$380), for example, has elastomers of three different densities in its "stack." At 3 pounds, the Manitou 4 is about as light as they come.

Elastomers have problems, however. They go hard in cold temperatures, they suffer from poor rebound, and have a slow response and uneven spring rate. And, of course, they're heavy. Compare the Ruby ($490), the 2.6 lb, elastomer/spring road fork manufactured by Rock Shox, with a typical, $100 rigid aluminium fork weighing 1.1 lbs, or carbon aero forks at 0.8 lbs.

Hybrid shocks are also available, which combine the advantages of elastomers and oil-damping or coil springs. Rock Shox produces a line of Judy forks (US$410-$600) which use oil damping to better tune the compression and rebound, and have been enthusiastically received by the racing crowd. The Indy series combines a coil spring with an elastomer of urethane in the Indy C and MCU in the more expensive XC and SL variants. The Rock Shox Quadra 5 (US$200) doesn't combine techniques and thus requires little maintenance, but it shows by bottoming out on big obstacles and bouncing all over because of the lack of damping.

Linkage Forks

Linkage forks use a completely different technology. The fork blades are rigid, with a hanged parallelogram where they meet soaking up the shock at the top. These forks tend to be lighter, absorb shock symmetrically (instead of one side having more give), and only moderately expensive. The Amp (US$350) weighs a mere 2.5 pounds, and is great for aggressive riders that squash other forks. Girvin makes a similarly solid Vector 2 ($450), at 2.8 lbs a smidge lighter than the Indy SL.

Air Springs

These shocks use cartridges sprung, and sometimes also dampened, by air. Air flows between two chambers, regulated by an adjustable valve. Most rear shocks, and suspension for motorcycles, cars, and elevators are all based on this design. The nature of the technology makes it extremely adaptable to rider weight and conditions, giving the full amount of travel in every situation. Air springs are lightweight and offer a decent ride, and are even available in retrofit kits for the Manitou, Judy and Quadra for about a hundred bucks. Air/oil shocks are best with large jolts, and make up the most expensive shocks. Rock Shox's SID ($700) uses an oil-bathed air shock to cut the weight down to 2.4 lbs. However, as more shocks use the cheaper elastomer technology, there is a great opportunity to pick up discontinued Rock Shox Mag21 or Marzocchi XCR2 forks for around US$250.

Unified Rear Triangles

Dualies have long suffered the "pogo" effect, where the drive train is split by the shock, which proceeds to soak up the rider's pedalling effort when mashing the pedals on a hill. The latest designs have unified rear triangles, where the crank and hub are connected with nice, rigid metal, on a triangle that rotates as a whole. Unfortunately, you have to buy the frame with the shock, and suspension frames are not cheap at all, adding at least as much to the price as front suspension.
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