There's a big oil/grease seal in the retainer nut for the sprocket side bearing. The existing bearings have a lip seal on the outside faces and are open on the inside, so I can't quite see what this seal seals. The only grease on the seal would be for the seal. I am installing double sealed (2RS) bearings.
Why should I install a seal? It will just add (not much) friction while only sealing in the grease I put on the seal lips... the bearing seal should keep out any crap... there's no extra seal on the brake side (which will be full of brake dust).
