The Shimano BB-MT501 is the designated Deore-level threaded bottom bracket, serving as the high-value successor to the ubiquitous SM-BB52. Designed for mountain and trekking bikes, it is engineered to house 24mm spindle cranksets (Shimano Hollowtech II) within a standard BSA threaded frame. While it remains budget-friendly, the MT501 features an updated sealing construction that significantly improves mud and water resistance compared to previous generations, making it a "set-and-forget" component for daily trail use and commuting.
The "68/73mm" designation refers to its universal compatibility with the two most common English-threaded shell widths. By using the three included 2.5mm spacers in different configurations, this single unit fits perfectly onto almost any standard mountain bike frame. With anodized aluminum cups and high-quality sealed steel bearings, the BB-MT501 provides a stiff, stable platform that ensures efficient power transfer every time you put pressure on the pedals.
Hollowtech II Integration: Specifically designed to work in harmony with Shimano’s 24mm integrated axle system, providing the optimum balance of stiffness, weight, and rotating performance.
Enhanced Sealing Structure: Features a revised seal design that noticeably extends service life by preventing trail grit and moisture from reaching the internal bearings.
Universal 68/73mm Fitment: Includes three 2.5mm resin spacers, allowing it to be adapted to both 68mm and 73mm shell widths (and various E-type derailleur or chain guide setups).
Anodized Aluminum Cups: Precision-machined and anodized for high corrosion resistance and a clean, matte aesthetic that matches modern groupsets.
Maintenance-Free Design: The sealed cartridge units are designed to be replaced as a whole, ensuring consistent performance without the need for periodic bearing overhauls.
High Driving Efficiency: Engineered with smooth-rolling steel balls that minimize mechanical drag, helping you maintain momentum on climbs and flats alike.
| Feature | Specification |
| Interface | BSA (English Threaded) |
| Shell Width | 68mm / 73mm |
| Spindle Diameter | 24mm (Hollowtech II) |
| Material | Aluminum (Cups) / Steel (Bearings) |
| Series | Deore M6100 / M5100 |
| Average Weight | ~92g |
The Daily Trail Rider: If you need a reliable, cost-effective bottom bracket that can handle mud, dust, and frequent washing, the BB-MT501 is the industry standard.
Shimano Crankset Owners: This is the native partner for Deore, SLX, and XT 24mm cranks, ensuring perfect chainline alignment and bearing preload.
Hassle-Free Maintenance: Ideal for riders who prefer a simple, threaded installation that can be serviced with a standard BB tool (like the Shimano TL-FC32).
Press-Fit Frames: If your frame does not have threads in the bottom bracket shell (common on many high-end carbon frames), you will need the BB-MT500-PA instead.
SRAM DUB or GXP Cranks: Shimano bottom brackets are strictly for 24mm spindles. They will not fit SRAM DUB (28.99mm) or GXP (stepped 24/22mm) cranksets.
Getting the spacer configuration right is the most important part of the install! For a standard 73mm shell, you typically use one 2.5mm spacer on the drive side. For a 68mm shell, you use two on the drive side and one on the non-drive side. Always apply a generous layer of anti-seize or waterproof grease to the frame threads before installation; this prevents the aluminum cups from "galling" or seizing into the frame over time. Remember: the drive-side (right) cup is reverse-threaded (lefty-tighty), while the non-drive side is standard. Torque them to 35-50 Nm to ensure a creak-free ride!
