Shortly after we told you about the launch of the new Willières Turbine SLR time trial bike with an aerodynamic fairing on the rear derailleur, riders were spotted at the Giro d'Italia using similar components.

Spotted on Giacomo Nizzolo's (Israel-Premier Tech) Factor Ostro VAM, this derailleur cage appears to be similar in design to the SLF Motion Evo Aero (opens in new tab) and appears to be of solid construction. But after a little digging, Cycling News understands that this component is actually an unreleased aerodynamic oversized pulley wheel from marginal profit specialist CeramicSpeed, Triathlete (opens in new tab) reports, The retail price for this component is $800.

According to the same report, the system was developed in collaboration with CeramicSpeed and Drag2Zero, a British aerodynamics consultancy.

At this time, details of the product's construction are unknown, but from the available images, it appears to be a complete pulley wheel system similar to CeramicSpeed's existing OSPW and Absolute Black's Hollowcage. The obvious difference, however, is that the device is covered by an aerodynamic carbon fiber fairing with a rounded leading edge and an open trailing edge

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It is black in color, but easily identifiable by the white spikes extending backward to mimic wind direction.

Those familiar with UCI equipment regulations may inquire about compliance with Article 1.3.024." Protective screens, fuselage-shaped fairings, or other devices added to or mixed with the structure that have the effect of reducing or decreasing resistance to air ingress or artificially accelerating propulsive forces are prohibited."

In the absence of official confirmation from CeramicSpeed or Israel Premier Tech, we asked the UCI for clarification.

"The UCI is aware of this product and is in ongoing dialogue with the manufacturer," explained Michael Rogers, Head of Road and Innovation at the UCI. "The product is considered to be a derailleur cage, a structural part of the rear derailleur."

"The UCI is aware of this product and is in dialogue with the manufacturer.

Rogers also clarified the UCI's rules on commercial availability. "With respect to commercial availability requirements, this product complies with UCI Regulation 1.3.006 (open in new tab).

Although it appears to be a novel idea for limited profit, this is not the first time riders have used sealed derailleur cages. Fabian Cancellara and Lance Armstrong use similar devices from the German company Berner. The aforementioned SLF Motion is just one of the companies touting aero cages as the latest gain for cyclists and triathletes.

There are no official details about this product and therefore no information about the aerodynamic benefits it offers to users. The existing CeramicSpeed OSPW claims a savings of 2 to 4 watts due to reduced friction in the drivetrain. However, the slight gains are only marginal, and each watt is an accumulation of one watt.