We can only speculate about this inverted Fox fork spotted at Sea Otter

A prototype Fox inverted mountain bike fork was on display at Sea Otter, but the brand is tight-lipped on the specs. So we got out our tape measure.
By Jeff Barber
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Close-up of a mountain bike featuring a white and gold frame, a black front fork with the "RAD" prototype label, and a Schwalbe tire. The bike is displayed against a blurred background, emphasizing its detailed components, including a disc brake and sturdy pedals.
Photos: Daniel and Jamieelee Palma

Clearly the inverted Fox mountain bike fork with signature Kashima coating on display was positioned to grab attention. But not too much attention. The brand is being tight-lipped about the prototype, which is shown here mounted to what appears to be a Pivot Firebird, an enduro bike that is normally specced with a 170mm fork. The Racing Applications Development (RAD) fork was also spotted mounted to an Orbea Wild electric trail/enduro bike.

Daniel and Jamieelee managed to get a tape measure up close to the fork, and it appears to offer 150mm of travel, give or take. Estimating the size of the stanchions is trickier based on our angle, but they appear to be in the 36mm range.

Close-up view of a mountain bike's front suspension fork and wheel, showcasing the tire tread, brake system, and frame details on a wooden platform.
Close-up view of the front wheel and suspension fork of a mountain bike. The bike features a black and gold suspension fork with the word "Prototype" printed in green. The tire has a rugged tread design and is labeled with the brand "Schwalbe." The frame is predominantly white with gold accents. The background shows blurred figures and equipment, indicating a biking event or exhibition.
Close-up view of a mountain bike showcasing the front wheel and suspension system, featuring a black and gold fork, knobby tire, and a white frame with gold accents. The background includes blurred shapes and colors indicative of an outdoor event.

Fox reps tell us they’re collecting feedback from pro riders and the overall market (ie bike brands and consumers) to determine if the product will ever be produced.

RockShox is no longer offering their inverted fork, the lightweight and XC-oriented RS-1. Other brands, including Wren and Intend, currently offer inverted MTB forks. The design also allows dirt and contaminants to flush out more easily as the fork compresses.

Without a traditional arch, this prototype Fox fork has the potential to save weight, and possibly accommodate a range of wheel sizes.

 
Close-up view of a mountain bike's front suspension fork and handlebars, featuring a frame labeled "Commencal Bikes." The fork has orange and black components, with blue knobs for adjustments, and the tire shows dirt, indicating off-road use. The background consists of natural greenery.
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