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by Dave Rome
May 14, 2020
Photography by Corima
Corima, the French carbon racing wheel company, has tossed its flannel beret into the gravel wheelset ring. The company’s new G30.5 merges modern tubeless technology with Corima’s unique use of a structural foam-filled rim, a beam-type rim design, and French-made construction, too.
A common theme across Corima’s entire carbon wheel range — and something that’s been true for more than 20 years now — is the use of a carbon fibre “bar” for the entire rim bed, upon which the rest of the rim is built. Dubbed “torsion box technology”, Corima claims it produces a rim that’s stiffer, stronger and more resistant to compression under inflation.
The structural foam fill is another feature that’s something of a signature of Corima’s wheels, something the company claims helps to absorb vibrations and deaden noise. Specific data on such a claim is limited, but at the very least, the structural foam core would assist in carbon compaction and improving impact resistance, two things that can’t hurt in a wheel designed for riding off-road.
Corima’s “torsion box technology” forms the structural foundation of the rim.
What is new is the “TSS” (tubeless straight side) rim profile, otherwise known as a hookless bead. Here Corima has chosen a 22 mm internal width with a 28 mm external dimension. That width is perhaps a little narrow compared to the latest gravel wheels coming from trend-pushing American companies but is rather progressive by French standards. Corima states that the sidewalls are reinforced for impact protection.
Rim dimensions and a rough graphic showing the construction of Corima’s wheels.
Speaking of French standards, the new G30.5s are said to comply with the ETRTO tubeless standards. Whether that’s the existing or upcoming rumoured new-and-improved standard is somewhat unclear. I’m guessing it’s the latter as Corima claims a 72.5 psi maximum tyre pressure, coincidentally (or not) the same as what Zipp also states for its brand-new 303 S wheels which feature a hookless bead.
The rim design requires the use of rim tape to create an airtight tubeless seal. Meanwhile a patented system, given the catchy name of “Internal Foam Core Overpressure Protection System”, offers a check valve to relieve air pressure from the foam-sealed rim if the tubeless rim tape fails.
A reliable base.
The wheels are built around the always dependable, and newly updated, DT Swiss 240 EXP centerlock hubs. This also means it’s easy to source the parts and make the switch between whatever freehub fitment you desire. They’re laced up with 24 Sapim CX-Ray spokes, front and rear.
Including tubeless valves and tape, Corima claims the wheels weigh 725 g and 825 g, front and rear respectively. That gives a total wheelset weight of 1,550 g — not bad, but perhaps telling that the unique rim technology does carry a penalty. They’re available in a 700c size, and for disc-brake use only.
Expect to pay US$2,000 for a pair of these wholly European-made hoops.