CeramicSpeed first introduced the original OSPW aftermarket derailleur cage in 2015, and in addition to claiming to be the fastest derailleur cage on the market, it certainly had the highest price tag of any derailleur cage on the market. The OSPW is one of the most polarizing upgrades to have happened in the seven years since, and it’s about to become even more so now that CeramicSpeed unveiled its OSPW Aero system today.
First spotted at the Giro and Ironman World Championships last month, CeramicSpeed has now officially announced the OSPW Aero rear derailleur that puts an aerodynamic twist on its aftermarket derailleur cage and claims to make the world’s fastest pully wheel system even faster. to make.
Internal chain routing anyone?
The OSPW is a marginal gain in every sense of the word, with some suggesting that the system built around the large pulley wheels offers only a single watt improvement in efficiency. While even CeramicSpeed’s efficiency claims don’t put the improvements much higher at just two to four watts. Still, a watt is a watt.
While the improved drivetrain efficiency claims associated with oversized pulley wheels are fairly widely accepted, many have questioned whether such modest improvements to the original OSPW are negated by an increase in drag from the larger derailleur cage. Oh and the price, many have wondered if saving between one and four watts was worth that much money.
CeramicSpeed has moved to blast at least one of those question marks with the OSPW Aero introducing a significantly redesigned derailleur cage with a new aero profile, which certainly looks a lot faster. Aero-shaped oversized derailleur cages aren’t exactly new, with Fabian Cancellara riding Tour de France time trials over a decade ago with similar setups. While it may resemble Cancellara’s cage from a decade ago, CeramicSpeed’s new OSPW is the result of a collaboration with aerodynamicist Simon Smart, known for Drag2Zero, Enve and F1, and a two-year design process involving multiple design iterations and wind tunnel tests. have been researched.
Since this (the derailleur cage and pulley wheels) only represents about 1% of the total system drag, we knew we had a challenge, especially since the rear derailleur cage sits at the most complicated flow area on the bike, and also considering the position and angle changes. This is one of the most complex parts of the bike to develop.
Simon Smart, founder of Drag2Zero.
The process involved testing “alternative pulley layouts that improved aerodynamics,” but were ultimately deemed too expensive in terms of reduced powertrain efficiency. The end result of the design process is a new derailleur cage that effectively encases the existing OSPW pulley wheels and a mechanically optimized design in an aero shell. A bit like a fairing, but certainly not a fairing if the UCI asks for it.
CeramicSpeed and Drag2Zero wind tunnel tests show that the OSPW Aero locally reduces drag by an average of 40% and up to 60% compared to a standard derailleur cage and pulleys. While that sounds like a huge savings, it’s worth considering that this is 40% of the 1% a derailleur cage contributes to the rider’s overall drag. CeramicSpeed claims these savings translate into a pro rider saving 2.5 seconds on a 25km time trial at 50km/h. In other words, not enough for Fignon to fend off Lemond, but easy enough for Serhiy Honchar to have Laurent Jalabert overhauled and avoid the painful three seconds he suffered at the 1997 World Time Trial Championships, the closest finish ever between the first and second at the event.
The savings would be much greater over longer distances with CeramicSpeed, suggesting that a competitive age-group triathlete riding at 30 mph will save 1:15 over a full-distance Ironman with the OSPW Aero compared to a stock derailleur.
Weight-wise, the new cage adds about 50g compared to a stock derailleur cage, although it was never intended to be a weight upgrade.
CeramicSpeed has released a white paper detailing the aero testing procedure and results, but priced at US$799 / £635 / €729, for many the marginal aero gain may not be enough to cover the overpriced price tag or maybe to justify even more questionable aesthetics.
A question mark in the shape of a fairing
The UCI regulations state: “A fairing is defined as the use or modification of a part of the bicycle in such a way that it encloses a moving part of the bicycle, such as the wheels or chainset. Therefore, it should be possible to pass a hard card (such as a credit card) between the fixed structure and the moving part.”
The OSPW Aero certainly seems to violate this rule enclosing the moving pulley wheels. However, the UCI has approved the OSPW Aero for use in competitions. The only explanation (read loophole) we can imagine is that CeramicSpeed managed to fit a credit card lengthwise along the new cage wall and between the top and bottom pulley wheels.
Regardless of how it passes the UCI inspection and how many watts it saves, I want an OSPW Aero partly for any aero gains, but mostly because I could legally have a fairing on my bike.
Now if manufacturers could find a loophole for head tube and down tube fairings to enclose hoses and cables for externally routed internal cable routing, wouldn’t the world be a better place?
The CeramicSpeed OSPW Aero is now available with compatibility options for Shimano Dura-Ace and Ultegra 12speed Di2 9250/8150, Shimano Dura-Ace and Ultegra 9100/8000, and SRAM Red/Force AXS.