CeramicSpeed OSPW RS ALPHA — Shimano Dura-Ace/Ultegra Di2 (9250/8150)

An oversized pulley wheel system that takes free watts out of your derailleur. The CeramicSpeed OSPW RS ALPHA fits Shimano Dura-Ace R9250 and Ultegra R8150 Di2 rear derailleurs, replacing the stock pulleys and cage with a hand-built, ceramic-bearing system that runs quieter, lasts longer, and saves measurable energy on every ride.

Why riders choose OSPW RS ALPHA

Oversized 13T + 19T aluminium pulleys with hardened stainless-steel ceramic bearings. Stock 11T pulleys force the chain through tight bends that bleed watts and wear the chain prematurely. Larger pulleys reduce chain articulation and friction so you save real wattage at threshold and your chain lasts noticeably longer.

Up to 60% less drivetrain friction vs stock. Most riders accept derailleur friction as invisible, but it costs 2–3 watts at race power — exactly when you can least afford it. The OSPW system gives those watts back so you finish climbs and breakaways with more in the tank.

Carbon-fibre cage with sealed pivot. Cheap aftermarket cages flex and let the chain skip under hard sprints. The reinforced ALPHA cage stays rigid through full-power efforts so your shifting stays crisp from the first interval to the last.

Custom seal, 60% better moisture protection. Wet rides and pressure washing kill ordinary derailleur pulleys within a season. The redesigned seal blocks water and grit so the bearing keeps spinning quiet through winter base miles, gravel detours, and every post-ride hose-down.

Plug-and-play install in under 15 minutes. No chain length change, no derailleur recalibration headaches — it bolts straight onto your existing R9250/R8150 derailleur with the supplied tools.

2-year warranty, 60,000 km service interval. CeramicSpeed backs the system for 2 years and the bearings are designed to outlast 3+ chains.

What's in the box

• OSPW RS ALPHA cage with 13T + 19T ceramic-bearing pulleys
• UFO TECH All Round Bearing Grease (5 ml)
• Mounting hardware + install tools
• CeramicSpeed decal

Fitment

• Derailleur: Shimano Dura-Ace RD-R9250, Ultegra RD-R8150 (Di2 12-speed)
• Drivetrain: 12-speed road
• Discipline: Road, Tri
• System weight: 96 g

Confirm your derailleur model code (printed on the inside cage) before ordering. If you're unsure, contact us and we'll confirm fitment for your bike.