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Your cart is empty.The Shimano UN300 English Bottom Bracket High quality sealed bottom bracket with a squared taper. The new chain line stabilizer helps to increase chain reliability. The adapter material is extra strong Aluminum. For use with JIS square tapered crank sets. The spindle is hollow and crankarm fixing bolts are sold separately. Available in Shell lengths 68mm or 73mm. Available in Spindle lengths 68mmx107mm, 68mmx110mm, 73mmx113mm, 68mmx115mm, 68mmx117.5mm 73mmx118mm, 73mmx122.5mm, and 68mmx127.5mm.
2manyshoes
Reviewed in the United States on January 2, 2025
I have not used it yet, but I plan to put it on a bicycle. That's what it's for.
Maht45
Reviewed in the United States on September 9, 2024
I had to use a Shimano crankset regarding I couldn't find my Sugino original chain rings. The Q Factor of the Shimano was two inches (in total) wider than my Sugino, and it caused much higher forces on the bottom bracket bearings.I returned the right original crankset, and it will work much longer this way.
JTAdone
Reviewed in the United States on July 9, 2024
Installed nicely. Exact fit. Ultra high quality. 65g lighter than the stock BB that came on my older Specialized bike. Would buy again.
ToolmanJohn
Reviewed in the United States on July 20, 2024
Made a "new" bike using an old frame. I'm glad there's still some parts that Shimanos continues to make , like bottom brackets for square taper standards. The Shimano UN-300 bottom bracket is 68/73 width, was easy to install, and smooth bearings. Will last for years and years.
Customer
Reviewed in the United States on March 17, 2024
Easy to install. Perfect fit.
Mechanical Side of Things
Reviewed in the United States on May 31, 2023
Went in with no fuss and is silent as can be. No telling on longevity, but the previous one lasted twenty years of hard, off-road use and was still technically function, just squeaky.Was a fun job, first time doing it myself. Much easier than I imagined and was great to save the $$ vs a shop visit.
mike
Reviewed in Mexico on May 23, 2023
La bici se siente un movimiento suave y ligero al pedalear con este eje y es ligero. Fácil de instalar, si se tiene la herramienta adecuada para ello
RichardC
Reviewed in the United States on August 30, 2022
The BB on my 1996 Giant mountain bike wasn't bad but I felt like doing some maintenance and upgrades. After following some Youtube videos, I felt confident enough to change the old one with this new one. If you don't have one, you'll need a crank arm puller which isn't that expensive but necessary to have. Luckily, none of the threads were frozen so removal was rather easy. After cleaning out the BB shell, reassembly was straightforward and easy. The whole project took about 45 minutes. When everything was buttoned up, I took the bike for a test ride. I was impressed by how smoothly the crank turned and the bike seemed to have a new life. You'll need some grease for the threads plus a 20-tooth spline to unscrew/re-tighten the cups.
J. Kirk
Reviewed in the United States on July 22, 2020
I have been slowly upgrading/replacing parts on an old Nishiki mountain bike. The latest part to die was the bottom bracket. This one was super easy to install. All in all it took me about 15 minutes to remove the old one and install this one. Went on my first ride after and it was super smooth.
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