Shimano BB-UN300-K Square Type Bottom Bracket

The Shimano BB-UN300-K is a durable square taper bottom bracket designed to deliver consistent performance. Its cartridge bearing system ensures smooth rotation and long-lasting reliability, ideal for various cycling applications.

Precise Compatibility: With a 68mm BSA threaded shell and a 122.5mm spindle length, the BB-UN300-K is compatible with a wide range of square taper cranksets. This bottom bracket also includes a 0.7mm spacer for precise fitment, ensuring optimal alignment and functionality.

Enhanced Durability: Built to withstand rigorous use, the BB-UN300-K features Shimano’s renowned quality and performance. The sealed cartridge design keeps out dirt and moisture, providing a maintenance-free solution that stands up to challenging conditions.

Optimized for Chaincases: Specifically designed for chaincase systems, this bottom bracket is a great choice for bikes with enclosed chain setups. It ensures smooth drivetrain operation while offering protection against environmental elements.

The Shimano BB-UN300-K is user-friendly, with straightforward installation for mechanics and DIY enthusiasts alike. Whether upgrading or replacing, it offers excellent performance and reliability for square taper cranksets.

We ship across India. Shipping is free on orders above ₹2,000, and ₹99 is charged on orders below ₹2,000. Cash on Delivery is available for orders up to ₹20,000, with additional COD charges based on order value. Most orders are delivered within 3–6 working days, though delays may occasionally occur. Please note that most Shimano products may take longer to ship. View full shipping policy.

Returns can be initiated within 7 days of delivery. Items must be unused, in original condition, and returned with all tags and packaging intact. Returns are available only on select categories such as apparel, helmets, jerseys, gloves, and similar items. Wetsuits and products discounted above 5% are not eligible for return.

Returns are not accepted for compatibility-related issues unless the product description on our website was incorrect. Return shipping must be arranged by the customer, as pickup is not available.

For eligible returns, you can choose an exchange, store credit, or a monetary refund. Refunds are processed after deduction of applicable shipping and transaction charges. Order cancellations are only possible before the order is processed. View full Return & Refund Policy.