You may have seen conspicuously large derailleur pulleys at use in WorldTour races or elite-level triathlons. CeramicSpeed is one of the companies making such pulley systems — which reduce mechanical drag slightly by opening chain-wrap angles — and now the company has a 13/19t system for the latest Shimano Dura-Ace derailleurs.
CeramicSpeed's Oversized Pulley Wheel System (OSPW System) for the new Dura-Ace 9100 mechanical and 9150 Di2 derailleurs can fit cassettes of up to 32t.
CeramicSpeed's other OSPW options for Shimano and SRAM derailleurs use dual 17t pulleys (modern derailleurs typically use 11t pulleys), but the new Shimano derailleurs don't allow for an upper pulley wheel larger than 13t. So, CeramicSpeed opted to enlarge the lower pulley way up to 19t.
CeramicSpeed claims that the new Shimano OSPW System reduces friction by 30 percent, compared to stock Shimano pulleys. In addition to opening the chain-wrap angles, the OSPW System uses ceramic bearings, which roll more smoothly than standard steel bearings.
Dimension Data rider Nathan Haas recently took fourth at the Amstel Gold Race on the CeramicSpeed OSPW System for Shimano 9100.
The system is selling now for $499, and will begin shipping May 9.