The Shimano SM-BB5700 [paid link] bottom bracket is a part of the 105 series and designed to meet the demands of serious road cyclists who prioritize smooth pedaling efficiency and long-term reliability. However, with similar-looking alternatives like the Shimano SM-BB4600 from the Tiagra line, it’s easy to confuse these two Hollowtech II threaded bottom brackets.
This article provides a detailed comparison of the SM-BB5700 [paid link] and SM-BB4600, diving deep into their construction, compatibility, performance characteristics, and ideal use cases—helping riders choose the most suitable option for their drivetrain configuration and riding style.
Component Design and Construction Quality
SM-BB5700 [paid link]:
Built with higher-grade materials, the SM-BB5700 is optimized for improved rigidity and bearing durability. It features better sealing to resist water ingress and debris, which directly supports smoother bearing performance over time. The unit is constructed with anodized aluminum cups and high-grade steel bearings that are precision-sealed to reduce friction.
SM-BB4600:
While the SM-BB4600 shares the Hollowtech II platform, it uses a slightly downgraded bearing quality and cup finishing compared to the 5700. The seals are functional but not as robust, meaning wear and resistance to contamination can become issues under harsher riding conditions or with minimal maintenance.
Verdict: The SM-BB5700 offers a marginal but measurable improvement in long-term performance and wear resistance due to its superior sealing and bearing quality.
Drivetrain Compatibility
SM-BB5700:
Specifically designed for the Shimano 105 5700 series crankset, the BB5700 is best used with Hollowtech II road cranks that have a 24mm spindle. It is also compatible with many other Shimano Hollowtech II road cranks across Ultegra, Tiagra, and even Dura-Ace lines, provided they use the same spindle diameter and BSA threading.
SM-BB4600:
Geared toward Shimano Tiagra 4600 cranksets, the SM-BB4600 uses the same BSA (British Standard Thread) and Hollowtech II specifications. Compatibility extends across lower-tier cranksets like Sora and Claris that adopt similar specs.
Verdict: Both bottom brackets use the same Hollowtech II interface and threading standards, making them mechanically interchangeable. However, performance and longevity expectations differ.
Intended Rider Profile and Use Case
SM-BB5700:
Suited for dedicated road cyclists who ride in diverse conditions—rain, grit, and steep climbs. This bracket is built for higher power output and regular training schedules, where durability and minimized friction matter.
SM-BB4600:
Ideal for casual riders, commuters, or fitness-focused cyclists who want a reliable and affordable component without the expectation of race-level [paid link] performance. It works well for entry-level [paid link] or budget builds.
Verdict: Choose SM-BB5700 if you’re performance-oriented or ride extensively; choose SM-BB4600 if you’re prioritizing cost and moderate usage.
Longevity and Service Life
SM-BB5700:
Thanks to better bearing sealing and high-quality internal grease, the SM-BB5700 generally outlasts the SM-BB4600 in mileage. Many riders report over 10,000 km of smooth operation before any signs of deterioration.
SM-BB4600:
Though still reliable, the SM-BB4600 tends to require earlier replacement, especially when exposed to wet or gritty environments without frequent maintenance.
Verdict: The 5700 offers a longer maintenance interval and lower lifetime cost in demanding riding conditions.
Installation and Maintenance Considerations
Both the SM-BB5700 and SM-BB4600 install using standard Hollowtech II tools and procedures. Grease application on the threads and proper torque setting are essential. However, the SM-BB5700 tends to require fewer bearing adjustments over time due to tighter manufacturing tolerances.
Price-to-Performance Ratio
While the SM-BB5700 carries a slightly higher price tag, it often justifies the premium with increased longevity, smoother spin, and better protection against the elements. The SM-BB4600 appeals to riders on a budget or those who plan minimal riding over the course of a season.
Technical Differences Overview Table
| Feature | Shimano SM-BB5700 | Shimano SM-BB4600 |
|---|---|---|
| Series | 105 (5700) | Tiagra (4600) |
| Bearing Quality | Higher-grade, smoother | Mid-grade, functional |
| Sealing | Enhanced, low-friction | Standard |
| Longevity | High (10,000+ km) | Moderate (6,000–8,000 km) |
| Intended Use | High-performance road | Entry-level [paid link], recreational |
| Price Range | Slightly higher | Budget-friendly |
| Compatibility | Hollowtech II Road Cranks | Hollowtech II Road Cranks |
| Thread Standard | BSA 68mm | BSA 68mm |
Conclusion
Choosing between the Shimano SM-BB5700 and SM-BB4600 ultimately comes down to riding goals and budget. If you’re building a road bike for competitive use, long-distance training, or just want parts that demand less attention over time, the SM-BB5700 is the better option thanks to its superior bearing quality and sealing. On the other hand, if your riding is light or infrequent and you’re looking for functional performance at a lower cost, the SM-BB4600 will serve you well.
For most serious road cyclists, the incremental cost of the SM-BB5700 is a worthwhile investment in efficiency and durability.