Ceramicspeed OSPW RS 5-Spoke for Shimano 105 R7150 Derailleur Pulley (Black)

CeramicSpeed's OSPW system replaces the stock Shimano derailleur cage and pulley wheels with a larger-diameter pulley set, which reduces how sharply the chain has to articulate as it runs through the derailleur. Less articulation means less friction, and over a full ride that adds up to a real, if modest, efficiency gain - the whole premise behind the OSPW line since CeramicSpeed introduced it in 2015.

This 5-Spoke version is built specifically for the Shimano 105 R7150 12-speed Di2 groupset, with a 13-tooth guide pulley and 19-tooth tension pulley mounted in a carbon cage, rated for cassettes up to 34 teeth. It's aimed at road, cyclocross, triathlon and time trial setups running 105 R7150 or the equivalent mechanical R7100 build.

It's a straightforward bolt-on upgrade for a 105-equipped bike rather than a full groupset change - the kind of component a rider adds once they're happy with everything else on the bike but still want to chase marginal gains.

Why You'll Like It

Larger pulleys, less chain friction
The oversized 13T/19T pulley wheels reduce chain articulation angle through the rear derailleur compared to the stock Shimano cage, which is the mechanism behind the claimed efficiency gain.

Built for your exact groupset
This version is specced precisely for 105 R7150, so there's no compatibility guesswork versus a generic one-size-fits-all pulley cage.

Cassette range covered
Rated up to a 34-tooth cassette, which covers the gearing most 105 R7150 riders are actually running, including wide-range builds for hillier routes.

Multi-discipline ready
Suited to road, cyclocross, triathlon and time trial use, so it's not a road-only upgrade if you split your riding across disciplines.

Who Is It For?

This is for the 105 R7150 rider who's already dialed in their bike setup and is looking for a bolt-on efficiency upgrade rather than a full groupset change - someone training seriously, racing, or simply chasing a smoother-feeling drivetrain on long rides.

It's a particularly sensible pick for riders doing long weekend rides or multi-day touring in India, where a drivetrain that's already running efficiently pays off more over distance than it does on a short commute.

It also suits a rider who's budget-conscious about upgrades but still wants CeramicSpeed-level componentry - this sits below their higher-tier Dura-Ace-specific options while still delivering the same core OSPW concept.

Good to Know

Have your bike shop check derailleur limit screw settings after installation, since a larger pulley cage can shift the derailleur's resting position slightly compared to stock.

Keep the pulley bearings clean and periodically check for play, especially if you ride in wet or dusty conditions regularly.

Double-check your cassette's largest sprocket size against the 34T maximum before ordering, particularly if you run a wide-range gravel-style cassette on your 105 build.

Technical Specifications

• Material: Stainless steel and ceramic components, carbon cage
• Pulley Teeth: 13T (guide) / 19T (tension)
• Cassette Teeth Max: 34T
• Compatibility: Shimano 105 R7150 (12-speed Di2), mechanical R7100
• Speed: 12 Speed
• Use: Road, cyclocross, triathlon, time trial
• In The Box: 1x CeramicSpeed OSPW RS 5-Spoke Pulley System

Additional Information

• Country of Origin: China
• Imported By: Ensign Sports, 502, Hill Glade, Opp. HDFC Bank Pali Road, Bandra, Mumbai - 400050, Maharashtra, India.
• Net Quantity: 1N