The FOX GRIP cartridge project scope was originally to make a low-cost mountain bike fork damper. Suspension engineer Damon Gilbert came to FOX in 2013 with plenty of suspension experience, and created our best performing, lowest friction, and most durable damper. Gilbert based his design on off-road motorcycle forks developed in the `90s, forks still being refined and used on high-performance motorcycles. It’s been proven to be durable, easy to work on and highly tunable, so why not apply it to mountain bikes?
The release of the FOX GRIP damper for MY2017 was relatively quiet since low-cost alternatives don’t excite the market very much. As more riders tried the FOX GRIP forks, though, people began to realize it performed better than the premium Factory Series forks. The GRIP damper was soon applied to the FOX Factory Series products.
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The high durability of this damper comes from its ability to ingest oil into the bottom of the cartridge and bleed it out of the top. This keeps oil fresh and circulating through the “closed cartridge” design and also keeps the oil and air separated to avoid cavitation and an emulsion situation. Since the top and bottom are both removable, it’s also really easy to work on.
Other dampers use rubber bladders to separate the oil and air, but rubber is porous and over time the air leaks from the bladder and mixes with the oil, causing foaming and inconsistent damping. FOX uses pistons with low-friction rubber O-rings to separate oil from air, but O-rings have much less surface area than bladders, so the chance to mix oil and air is exponentially reduced.
Our motorcycle engineering team took Gilbert’s patented technology (now on its second generation) and began applying it to V-twin use a year ago, leading to the recent introduction of the 49mm and 41mm GRIP-Street Performance cartridge fork kits for Harley-Davidson touring baggers.
ALL HAIL THE GRIP DAMPER!