Road Bike, Cycling Forums banner
1 - 3 of 3 Posts

Discussion Starter · #1 ·
Hey, through a recent bike swap, I have the chance to replace the Shimano 105 bottom bracket on my current road bike with a new Ultegra bottom bracket. All it would require is my taking off the crankset, removing the 105 bottom bracket, and putting everything back together with the Ultegra bracket.
I have some good tools, including a crank puller and a Craftsman torque wrench. But having little mechanical experience, is this something I should tackle?
I would like to learn how to do this, but not at the risk of messing something up.
Would the Ultegra bottom bracket be better than the 105 bracket? The 105 unit has about 800 miles on it and works fine.
Should I go ahead or just leave things alone?
Many thanks for your advice on this!

6,492 Posts
It's a reasonable job, but you won't notice a difference

It's pretty easy to do--only tough part is removing the "fixed cup," on the left side of the BB shell, but you can have a shop do that and install the new one if you like. I've done three or four BBs, and that's what I've done. If they know you, they may do it free, otherwise it's about a one-minute job. The rest is just assembly--any bike-repair book or can show you how.
The bad news: I don't think you'll notice a diference in any aspect of performance. One of the good things about Shimano is that the 105-level stuff (I think it's LX in mountain bikes; maybe not) works really well. I might do the swap if I had the parts laying around, but if I had to buy them, I'd wait until something broke.

376 Posts
Pretty easy job if you have the right tool

If you have a bottom bracket removal tool this is an easy job. Follow the instructions on the Park tool website and you will be fine. I have done this too many times to count, and short of having to always remember which direction to loosen or tighten it is never an issue. Make sure and grease the threads good if you do change it out. Also good that you have the torque wrench. You do want to be sure you have this tightened correctly.

I do agree that the 105 stuff is pretty good, and the quality difference will not be noticable. At such low mileage you would not need to replace it for a long time. Unless you "have to", I wouldn't mess with it.
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.