Shimano BB-UN300 Square Tapered Bottom Bracket

Shimano BB-UN300 Square Tapered Bottom Bracket


Regular priceRs. 830
Tax included.


The quality and performance-oriented Shimano BB-UN300 cartridge bearing bottom bracket features a JIS square taper mount and is designed for frames with BSA thread and 68/73 mm shell width. A stabilizer ensures a constant chain line.

  • Fits JIS square-taper cranksets
  • Crankarm fixing bolts sold separately
  • Hollow spindle
  • Adapter: aluminium (left), aluminium / steel (right)
  • Axle: steel

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Customer Reviews

Based on 2 reviews
Worth for money


Quality product from Shimano

Nice bottom bracket. I especially like the rubber lip seals on the covers which prevent dirt from entering the bottom bracket housing. Most lower end bottom brackets don't come with these. One recommendation to BOTS is to clearly give the actual dimensions of different sizes on the web page to make it easier to choose. It is always difficult to choose the correct size without trying it out practically. I got a wrong one at first and my chainline was not matching. Then I bought another one after much research and this one fits well.