Shimano UN300 Square Taper Bottom Bracket - BSA

Shimano UN300 Square Taper Bottom Bracket - BSA

Regular price£22.45

🚚 FREE Standard UK Shipping on all orders over £20

Shimano UN300 cartridge bearing Square Taper (JIS) bottom bracket with alloy cups. Successor to the UN26 and UN55 series, this component covers a wide range of applications from Touring and City bikes to older Road and Mountain bikes.

Suitable for traditional square mount chainsets, featuring a 68mm shell with BSA (English) 1.370" x 24tpi thread.

Crank bolts are not included.

We ship fast! Our stock levels are updated live and most orders placed before 14:00hrs are shipped same-day (Monday to Friday).

Each product page will show estimated dispatch times.


  • Standard UK shipping is FREE on all orders over £20.
  • Express shipping options are available on checkout.
  • We also offer Click & Collect from our Warehouse Mon to Fri 9:00 to 5:00 - kindly wait until we confirm your order is ready before visiting.


  • Europe standard shipping is £3.99 with an Express option available.
  • We have had to disable shipping to the EU. We hope to be able to resume shipping to more EU destinations shortly.


  • We have had to suspend shipping outside of the UK. We hope to be able to resume shipping worldwide shortly.

We offer a no-quibble 30-days refund policy*. There's no need to contact us before returning your item(s). Simply send it back to the following address:

Sprocket and Gear (Returns), Kingfisher Works, Tag Lane, Hare Hatch, RG10 9SH, United Kingdom

Be sure to include your order number and reason for return. Sorry, but we can't cover, or contribute to, the cost of the return.

* To read our full returns/refund policy please click here.


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Customer Reviews

Based on 1 review
Mark Rogerson
Direct replacement bottom bracket

I ordered from this company because the good photos of the product assured me that it was the correct model. It was very stiff to tighten on both sides but I atribute this to the advanced age of the bike frame. I could not have done this without the specialised tool and the 32mm socket.