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Shimano BB-UN300 68mm Shell Square Taper Bottom Bracket - English Thread

£19.99 Please note this product has selling restrictions to your country. was
Manufacturer : 
SJS Cycles part number : 
Manufacturer part number : 
- A good quality bottom bracket for traditional chainsets
- Super-accurate bearings for smooth operation and improved durability
- Durable, hard-wearing sealed cartridge bottom bracket with square tapered spindle fitting
- Maintenance-free sealed cartridge bearing assembly keeps out dirt, mud, and water for long bearing life
- Fast and easy installation without adjustment
- Narrow body allows clearance for cable routing under the bottom bracket
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Questions & Answers (4) Q & A
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Questions & Answers (4)
Thread length on this BB in reality
03 Feb 2021
Hello, are there really 13 threads on the RHS cup as per your picture please? What is the depth in mm from underside of the lip?
I have a UN300 in front of me with 9 threads/ 12mm max of threads from the lip underside.
I need just that few more threads due to a partially semi-stripped BB for peace of mind.
Thank you for your enquiry, from base of lip to bottom of thread is 12mm.

WD 03/02/2021
Will this fit with FSA triple chainset.
25 Oct 2020
Hello, can you please tell me if this is the right length to mount a FSA triple chainset to an old (1980s) raleigh bike that I am rebuilding. The width is 68 mm but I'm not sure of the length.
Thank you.
Hello, I'm afraid without knowing the existing length we cannot assist. The BB to crank arm fitting is correct but you need to ensure the BB shell threading, width and length are known in order to purchase a 1:1 replacement unit.


JK 26.10.20
Plastic / Metal Ring On Axle
24 Sep 2020
Hi guys, just wondering if you knew what the ring on the axle is for?

And if so is it removable?
The ring is a limiter, it is no removable.

Bracket bolts
30 Jul 2020
I was wanting to purchase the Shimano BB UN55 68 - 122.5 to replace my old bottom bracket but it is not in stock so I was advised that this bottom bracket is an alternative. Do I also need now to purchase different bracket bolts to fit this different model bottom bracket when purchasing it?
You can reuse the original bolts.

Thanks - 04/08/20