Originally Posted by cny-bikeman
Actually with most hubs if you try to put in the last ball there is not really enough room to have them run smoothly. Generally 10 front, 9 rear, 11 bottom bracket. There are exceptions but again generally 3/16 front, 1/4 inch rear and bottom bracket. Headsets are definitely fill and take out one, usually 5/32, sometimes 3/16 (old Schwinns used a 3/16 caged bottom and 5/32 caged top. Always a good idea to put in loose balls instead of cages, except for Campy and some other brands whose cages hold a full complement of balls. NEVER reuse ball bearings - they're meant to be sacrificial.
If you are just repacking as normal matainence (e.g. you re-pack several times a year NOT when things start grinding...)and the races/bearings are ALL in good shape there is no problem reusing them. If I do so each set of bearings go back with those they ran with. That being said now that I found a cheap source of grade 25 SS bearings I've gotten lazy and replace rather than clean.............
P.S. I still clean to look for pits, just don't clean enough to put them back in......