[PJ352]

Im looking to upgrade the shimano 2300 components that came on my sectuer. I plan on using this as a learning experience as to how bike components are installed and tuned.

Now the bike came with a un55 BB, this much I know. The question is, since I am buying a complete groupset, which type BB do i need? Will the BSA bb that comes with this Tiagra groupset work after removing the current un55?

Shimano Tiagra 4600 Groupset | Groupsets - Road Bike | Merlin Cycles

Thanks for the help!
Harry

The answer is, yes. Your current BB is a Shimano BB-UN55 Square taper. You'll be replacing that with Shimano's current Hollowtech ll BB.

That said, if you're going to be doing this work yourself, be aware that you'll need tools specific to those BB's for removal/ installation. IMO, if this is going to be a one time deal, let your LBS perform the work, then buy the tools you'll need to maintain the new BB.

This, of course, assumes you don't yet own the tools required.