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. Compatible with the 24 mm spindles found on Hollowtech II cranks. Claimed weight is 65 g.
B-Stock - This product has one or more B-Stock units available. These units can be purchased at a discount (see option select). B-Stock units were returned from other customers and may have missing or damaged packaging materials. These units are otherwise as new. The full manufacturer warranty applies. Click Here for more information.
Bottom Bracket STD: English (BSA)
Bottom Bracket Type: Shimano (24mm)
Frame Interface: BSA/English Threaded
BB9100 - English Thread
Mfg PartNum: IBBR9100B
BB9100 - Italian Thread
Mfg PartNum: IBBR9100I
Used this for a new gravel bike build. I had never installed a bottom bracket before and this was very simple and straightforward. Came greased and ready to install. Because of the factory grease, it doesn't spin extremely free to start, but it's loosening as it breaks in.
Like all Shimano Dura Ace gear, its top of the line. I was a bit surprised after installing it that the bearings seemed a little tight....not as free spinning as I'd expected.That said, it is very smooth. I expect that the bearings will ease up as I get more miles on them. I was replacing an old 7800 BB and that would have been impossible without the accompanying adapter. Not all sellers provide that adapter but they did. Thanks!
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).