I was setting up a Zwift setup for winter training and decided to pull an old bike down out of the garage rafters to give it a new life and the thorough going over.She was put to pasture once I became addicted to Di2, carbon EVERYTHING, disc brakes, and tubeless tires. On another tangent, I've forgotten how wonderful metal is as a frame material. The feeling and feedback is something that's gotten lost in the match towards "higher tech". This bike will now be the rotation again, once the weather warms and I purchase a set of tubeless wheels ...some tech advancements are just too good to ever go back.Ok, back to my BB review...The part arrived rather quickly and I hadn't finished putting on the new cable housing and cleaning/lubing the drivetrain so this was out on the back burner, since I wanted to get the Zwift sled up and running ASAP.In time I got the Zwift thing down and got the bike dialed in on the (Zwift) hub, so though now I had time to pop in the new bottom bracket.I knew the original Ultegra BB was ok and still turned smooth after 15 years and thousands and thousands of miles, but I bought this new BB on a whim when gathering up fresh parts for this project. I saw how Shimano claimed lighter weight and a 50% reduction in friction, but we know how "NEW AND IMPROVED!", sells so didn't buy too much into the hipe. I opened the box and thought I purchased the wrong part because the BB threaded shell looked WAY too small compared to the old one still in the bike 🤔I fished around the box looking for the advertised adapter that's supposed to come with the BB so you can use your older took to install the new gen BB, but it was nowhere to be found, which is why I dinged the review on ease of install ... be warned, you'll likely not have the right tool to put it in if you're used to servicing your old BB.Once the correct tool arrived I swapped in this new one, put the bike back on the trainer and put on my kit for a ride.🤯 I couldn't believe how much LESS energy it took to power the bike! Shimanos claims of friction reduction are not hyperbole. I could see it on in the Zwift data too, I put out fewer watts over the same courses I'd ridden several times. Data doesn't lie, this thing was a huge improvement in efficiency and you can see it in the data. To add to that, it cleans up the looks of the whole BB area and makes it look far more modern.In closing, even if you don't NEED a new BB you need this for the friction reduction and sleek looks and ... IT'S CHEAP!!!Get it, you won't regret it other than needing to buy the tool to install it if yours doesn't come with promised adapter! 👍🏽