Originally Posted by
stmalk
I'm sorry I missed it. So to get that lock ring off I don't need any additional tools? I can just hit it with screwdriver/hammer and unlock BB. But I think I still need a BB removal tool to get it out, just unlocking it is not enough.
And if I buy a new BB, will it have a new lock ring? And what tool would I need to lock it again.
For that type of BB the only special tool needed is for the lockring. The cups can be removed with an adjustable wrench.
Shimano cartridge bottom brackets are installed with this tool:
BBT-22 Bottom Bracket Tool | Park Tool
No lockring needed, the bottom bracket comes as a single unit that threads in from the drive side and a plastic cap for the non-drive side. That tool has a propensity to slip out of the bottom bracket so I've taken to using a metric m8 bolt about twice as long as the pedal bolts and a washer to hold the tool in place. Though slippage is a little less of an issue during installation than removal.
The video I posted earlier shows how to select a bottom bracket that will fit. Important measurements are the bottom bracket shell width and the spindle width.
edit: Part of the reason there are so many choices is because in addition to multiple sizes there are multiple product levels. The UN55 is a step up from the basic UN26. Not sure what the differences are, could be size / number of bearings, seals, weight. UN55 is still pretty cheap.