Product Description

SHIMANO 10021 IDLE GEAR B S (RD18905)

Restore Your Reel’s Precision

The Shimano 10021 Idle Gear B S is a genuine OEM replacement component designed to restore the smooth oscillation and drive performance of your Shimano spinning reel. Located within the reel’s body assembly, this small idle gear (Position B) is critical for transferring power from the drive gear to the worm shaft, ensuring perfect line lay and consistent operation.

If you are experiencing grinding noises, inconsistent spool movement, or gear slippage, a worn or damaged idle gear is often the culprit. Replace it with this authentic Shimano part to ensure exact fitment and factory-standard durability.

Product Specifications

• Part Name: Idle Gear B S (Small)

• Manufacturer: Shimano

• Part Number (MPN): 10021

• Alternate Part Number: RD18905

• Material: High-strength composite/plastic

• Installation Position: Internal body assembly (Drive/Oscillation system)

Compatible Models

This part is engineered for specific Shimano spinning reel series. Always verify compatibility with your specific reel size and generation.

• Shimano Stradic FL Series:

  • ST1000HGFL (Stradic 1000 HG FL)

  • Note: May fit other sizes in the FL series (e.g., C2000, 2500). Please verify against your schematic.

Installation & Reference

To ensure this is the correct part for your specific reel model, please cross-reference the part number RD18905 or 10021 with your reel's exploded diagram.

• Schematic Diagrams: For detailed PDF schematics and part location verification, please visit www.reelschematic.com.

• Alternate Part Number: RD18905

   

Note: Proper installation may require disassembly of the reel body. We recommend consulting the schematic to identify the correct orientation of the Idle Gear B S during reassembly.