Works great. Spins around and
"Works great. Spins around and around!"

Overall rating: 4.860465 / 5 from 43 reviews.
The Shimano UN300 Square Taper Bottom Bracket offers high-quality performance with a standard structure, featuring a Shimano Tourney TX800 Series cartridge bearing. It provides better chainline stability and is compatible with JIS square-taper cranksets. Customers appreciate its fast shipping, excellent service, and good prices.
Review topics: ["fit","size","quality","issues","shipping","price","works","service","bottom bracket","bracket","bearings","rotation","tool"].
"Works great. Spins around and around!"
"Perfect fit in my Trek bike. I wanted 150 mm cranks and the only ones I could find were square taper. This bracket works perfectly."
"I love a square tapered bb just like the next rivendell riding retrogrouch, but we all can agree; they’re a total guessing game when it comes to which length you need. There’s only so much sheldon brown you can read before you just take an educated guess and bite the bullet and buy the length you think you need. Well enter the un300, they’re cheap and work great! Definitely punches above it’s weight class. The best part, if you get the wrong size, it’s not the end of the world and now you have a spare bb sitting around for the next time you try to 1x your 90s xtr crank and are wondering which length you need. I have several of these kicking around in various lengths for that specific purpose. Did I also mention they work great? They work well enough that I run them even if I have some fancy sugino 75s or the paul square tapered cranks. If you feel inclined to be fancy and get a phil wood or white industries, now you know which length to get and it only cost ~$15 instead of $100"
"What can I say, it's a square taper BB. They're relatively cheap and come in all the sizes to help dial in chainline. Hoping this performs similarly to the old UN55s which were excellent."
"Old school bottom bracket: English threaded, lots of options. I bought this to accommodate a Stronglight triple crankset to mount on a 1970’s Witcomb frame with a 68mm bb. It fits well but it’s a bit wide for proper chain line, so I’ll probably step down to the next to largest size."
"Silky smooth BB. Can't beat this quality at this price."
"Solid BB! The cups are not the same dimensions as the UN55, so you need to use the actual cup provided. I wish the cup were plastic, but that is the minority position - I have a frame with sketchy bb threads. Other than that, just as good as the UN55 (RIP in peace)"
"Quality made Shimano Bottom Bracket 👌 And great price from Cambriabike.com!"
"Great product lighting fast shipping and great price"
"Perfect fit and best price on the internet! Did some internet research to double check sizing for two of my bikes. Both bb came well packaged and in a timely fashion. This was my first time ordering from Cambria but it definitely won't be the last. Thank you for the great service!"