This article originally appeared on BikeRadar
Danish bearing friction specialist CeramicSpeed is moving slightly outside of its comfort zone for its latest product: a complete rear derailleur pulley and cage assembly that the company says will save you up to 3W (based on a 250W output). The idea that bigger pulleys run faster is hardly revolutionary. The real question is how many folks will be willing to pay through the nose to get there.
CeramicSpeed outfits its new Oversized Pulley Wheel System with two enormous 17-tooth pulleys that will supposedly save nearly 2.5W over a stock Shimano Dura-Ace 11-tooth setup – and that advantage apparently grows another half-watt when using a less-than-perfect chain. According to CeramicSpeed, this is because the larger pulleys force the chain to bend less (and more slowly) per link for the same given rider speed, the pulleys themselves spin slower, and there's less tension in the lower span of the chain.
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As compared to typical 11-tooth pulleys (at right), CeramicSpeed's new 17-tooth pulleys look comically large
Naturally, CeramicSpeed also equips the machined-and-anodized aluminum pulleys with its own hybrid ceramic bearing cartridges, which are built with tighter tolerances than the ones used in the company's standard-diameter pulleys to better handle the increased side loading.
Despite the huge increase in pulley size, CeramicSpeed says that swapping to its OPWS assembly will only add 8-10g to a standard Shimano Dura-Ace rear derailleur. The cage plates are molded from lightweight carbon-reinforced polyamide plastic, and the pulleys are very liberally machined. CeramicSpeed wouldn't divulge exact figures but the company also claims that there's essentially zero increase in aerodynamic drag with the bigger cage – at least when accounting for a realistically wide range of wind angles.
You can read more at Cyclingnews.com
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