It’s no UN72 but for the money, wow, buttery smooth and beautifully precise like only Shimano does. It will probably outlast me and before I install it into its final resting place in my unicorn retro Kona, I’ll write a small note for the next owner of this bike, probably something inappropriate but poignant. TLDR: the finest square taper BB that will outlast your sorry carcass.

Typical Shimano quality at a competitive price. Read previous reviews before buying that compared the UN300 to the now discontinued Shimano UN55. Previous reviews say the UN55 was a better bottom bracket with better bearings and seals but with this no longer being available this model appears to be the next best square taper bottom bracket. It looks real quality and if this is anything to go by and it performs and last as good as it looks then it’s still good value for money.

Does the job

I've had this a few weeks now, my old bb needed replacing as soon as. It fitted easily and there was no problems at all, I'm reasonably happy with the performance although after a few weeks of riding everyday its got a squeak going on in the sealed bearings which makes me think it might be lacking some grease in there. It's a decent replacement until I upgrade to Hollowtech.

Easy Installation

I bought this product after changing from a double crank set to a triple crank set. My original was 124mm and this Shimano was 113.5. I worked out great in helping to align my chain rings with my rear 8 speed cassette.. I should point out that, when installed in my 68mm frame, the left crank was slightly farther away than the right chain ring side from the frame. This worked out well for me because it helped to align my chain rings with the 8 speed cassette better. There were no problems with installation, it went into the frame smoothly. Much easier to install than the cup and cone bottom bracket I had before. As I look at the picture, it shows some kind of black washer on one side. I don't remember that on the one I received, and I wonder if that may be the reason ... MoreI bought this product after changing from a double crank set to a triple crank set. My original was 124mm and this Shimano was 113.5. I worked out great in helping to align my chain rings with my rear 8 speed cassette.. I should point out that, when installed in my 68mm frame, the left crank was slightly farther away than the right chain ring side from the frame. This worked out well for me because it helped to align my chain rings with the 8 speed cassette better. There were no problems with installation, it went into the frame smoothly. Much easier to install than the cup and cone bottom bracket I had before. As I look at the picture, it shows some kind of black washer on one side. I don't remember that on the one I received, and I wonder if that may be the reason one crank is slightly closer to the frame on one side....I don't know. Anyway, it works well.

Economical and Functions Beautifully

I installed this into the BB shell of a 1994 Specialized Ultra, replacing an old decrepit, heavy, terribly rusted steel one that I happily junked. Thank you Cambria Bike! You totally made my day.

Good seals. Spins nice and quietly

Bought this to replace the BB on my 2021 Specialized Rockhopper. This unit is by far better quality than the one that came on the bike. It has more seals to keep grime out. It spins so smoothly and unlike the one Im replacing is ultra quiet.

My Bike is Smooth as Silk

Wanted to replace my bottom bracket as part of a complete overhaul, although the company bracket was working fine. But I realised what I was missing when I installed this. Absolutely smooth and glides like butter. Love it.

New design

I replaced an older shimano product with this. The cups on this one were much wider than the old one and are all aluminium where the old one had a plastic cup. This meant I had to clean up the Internal thread in my frame before it would fit but this was trivial compared to the task of getting the old one out. Now it's back together and feels like new while peddaling.

Nice deal!

Shimano 68x113mm for my 6-Spd bike, Tilt 120. It originally came with 68x118mm, however the 68x113mm does fit perfectly fine as an alternative. Great quality from Shimano. Good from a price point as well. However sticking to stock specifications would be highly recommended. Good deal nonetheless!! Thanks Cyclop.

Shimano BBUN300 Bottom Bracket British thread, 68 / 113mm

Replaced a previous one with the same model. The old one did well, hope the replacement does too.