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I've taken apart a road bike from the 70s with a (french) ball bearing bottom bracket. Looking inside I found (what I thought to be) absurd amounts of grease in the tubes coming into the bottom bracket. I'm a bike work beginner and intuitively I would've thought that's excess grease pushed into the tubes, but the sheer amount made me wonder whether it's there intentionally - maybe to seal off the tubes/bottom bracket?

Also haven't found anything on it yet on Sheldon Brown's website, but that might just be my fault.

picture of the inside of a bottom bracket with remaining old grease

Thank you for your help.

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    When I take apart a bottom bracket I will often grease the inside of the housing. Moisture tends to migrate down there, and the grease helps prevent rust. – Daniel R Hicks May 1 at 12:41
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Some mechanic might have put a liberal amount of grease in the BB shell and also in the head-tube prior to assembly. Then copiously greased the seat-post as well. Grease has a tendency to migrate, especially in hot weather and move to the strangest places, the bike may have been stored upside down, head or tail-up.

Think of it as a gift from whoever put it there, the coating also prevented the tubes from rusting on the inside. Wipe off the excess before re-assembly and repack the BB and the headset with fresh grease. In no case would I use solvent to clean the insides of the frame.

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