Shimano UN300 Square Taper English Bottom Bracket (Silver) (BSA) (68mm) (117.5mm)

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Spindle Length:

  • 107mm
  • 110mm
  • 113mm
  • 115mm
  • 118mm
  • 117.5mm
  • 122.5mm
  • 127.5mm
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Shimano BB-UN300 Square Spindle 68mm Bottom Brackets


  • Fits JIS square-taper cranksets
  • Crankarm fixing bolts sold separately
  • Hollow spindle

Frame Interface: BSA/English Threaded
Spindle Interface: Square Taper JIS
Bottom Bracket Shell ID: 1.37
Shell Width: 68mm
Spindle Lengths: 107mm, 110mm, 113mm, 115mm, 117.5mm, 118mm, 122.5mm
Color: Silver
Weight: TBD

This product was added to our catalog on August 13, 2021

Verified Owner
Monday, Jun 14 2021 (about a year ago)
Shimano UN300 Square Taper English Bottom Bracket (Silver) (BSA) (68mm) (122.5mm)
My 2017 Trek FX.2 had +7000 miles on it and was time to replace most of the moving bits. Replaced the bottom bracket with a UN300. The original bracket (VP BC-73) was 68 x 121.5 for JIS square-taper cranks. The UN300 was slightly longer (122.5 vs 121.5 mm) and changed the chain-line, requiring that the front derailleur needed adjusting. All-in-all, the UN300 easily fit into the bicycle frame and appears to be better quality then the original bracket.