Hi everyone my 80's road bikes bottom bracket has developed some sort of issue.

It has developed up/down movement (not inward/outward).

I immediately thought something was loose or the bearings were shot.

I replaced the bearings with new ones BUT the issue is still there!

Everything is tighten properly so I'm not sure what is wrong.

It rode fine until this issue escalated in less than 50 miles.

Any ideas?