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I was in the process of prepping to install a new BB on my bike when I noticed this remnant that I believe might be part of my old BB. To my novice eyes, it looks like something snapped and is now stuck:

Overview

View from "far side":

Far side

Alt view from "near side":

Near side

Can anyone help clarify what exactly I am looking at? I assume it needs to be removed before I can install a new BB? Do I need a new frame? Do I need to have a bike shop do recut the threads?

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  • What kind of bottom bracket was the old one?
    – ojs
    Commented Jul 24, 2023 at 9:56
  • @ojs I am unfortunately not sure, it came with the bike (archive.harobikes.com/mtb/2016-mtb/steel-reserve-1-3-2016). The crankset is described as "Haro chromoly 8 spline 2-piece crankset w/ 25t sprocket" but I can't find anything on the bottom bracket. Would pictures of the BB bits be helpful?
    – Terry T
    Commented Jul 24, 2023 at 11:06
  • I mean, was it the style with bearings outside the BB shell (looks like that in photos) or cartridge that contains the bearings that goes inside?
    – ojs
    Commented Jul 24, 2023 at 12:32
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    @ojs ah I see, my bad. You're correct, the bearings were outside the BB shell.
    – Terry T
    Commented Jul 24, 2023 at 13:22

2 Answers 2

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External bearing bottom brackets have a plastic spacer between the cups. The part that is shown in the photo looks like it's broken off from this spacer.

You should be able to push it out with a flat screwdriver, possibly helped with some heat or penetrating oil. If it's badly stuck, cutting it to pieces with hacksaw blade, careful to not damage the frame, might be necessary.

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You can try rotating it out with some kind of expanding fixture but it's unlikely to move. I'd give it a little hello with a file or hacksaw blade then try to tap it out with a brass drift.

It's just ... stuff... so do stuff with stuff. But if you don't feel confident go spend your bucks at a mechanics 👌.

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  • Can you clarify what you mean by a "drift"? I'm not familiar with that term, but googling "mechanical tool drift", I'm seeing tools very similar to what I usually call a nail set. I.e. a tool for concentrating and localizing hammer blows. So I can't picture how that would be applied here in conjunction with a hacksaw.
    – SSilk
    Commented Jul 24, 2023 at 8:39
  • Try 'brass drift' in Google ✅ Commented Jul 24, 2023 at 10:05
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    Can you please try re-wording the bit about "stuff" that doesn't really carry useful information. I'd try a little right-angle pick tool with a point to get down in the valley of the thread whereas a wider surface will be hitting the crests of the thread and risks mushrooming them.
    – Criggie
    Commented Jul 24, 2023 at 10:56
  • @Criggie the useful information it carries is found in the purposeful generality of the response. The repeat use of the term 'stuff' also hinting at its facetious nature. Commented Jul 25, 2023 at 2:52

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