The top of the bottom.
Like the 9000-series Dura Ace bottom bracket, the BB-R9100 is both lighter and more efficient than previous generations while remaining an industry leader in weather resistance and durability.
Using 19 slightly smaller ball bearings on each side instead of 15 larger ones shaves precious grams, and updated seals drop resistance by up to 75%. The cone profiles have also been redesigned for increased durability so the BB-R9100 can take the same amount of abuse as its larger-bearing forebears.
Available in English-threaded 68 mm shell and Italian-threaded 70 mm shell width versions. Includes TL-FC24 adapter for use with standard external bottom bracket tools designed for 44 mm OD cups. Compatible with the 24 mm spindles found on Hollowtech II cranks. Claimed weight is 65 g.
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Dura Ace is the way to go
1 of 1 customers found this review helpful.
Installed for my Dura Ace 7800 crankset. Installs easily, silent and smooth. Replaced my DA 7900 BB which had aftermarket ceramic hybrid bearings installed. The no load spin test is impressive. Real world, the Dura BB 9100 (or 7900 or 9000) is much better - smoother, quieter, less friction - yes folks... ceramics are not the best for low rpm (less than 10,000) applications. Ceramic hybrids wear poorly and create slop, noise, and increase friction. After several experiments and years of trying ceramic hybrid bearings, I'm sticking with DA stock (BB, derailleur pulley, and wheels).
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