Originally Posted by
Salamandrine
BB bearings got repacked about twice a year on average, more if caught in the rain. Fixed cups were not removed until the bottom bracket was worn out and replaced. It would have been silly.
With the cup removed you can lay a nice symmetrical bead of grease around the cup for the bearings to sit in, with the cup in the frame your ability to get a decent uniform bead of grease in the cup is notably reduced, so removing the cup likely saves time, and if you had it out 6 months ago it'll spin right out "now".
As a kid I did a lot of maintenance on a fleet of 30 rental mountain bikes (Chrome Mongoose ATBs), I always removed the fixed cup when servicing them, my boss was an old road racer, thats how he wanted it done, worked great for me then, and now.
I fully agree that a BB can be regreased with the cup in the frame, I just don't think its the best way to do the job.