do I need to grease these bearings?

I ordered these bearings from mcmaster to use in my new electric bike that i'm building for my senior project, but they spin really easily and im not sure wheather or not im supposed to grease them. and if I am, what kind of grease would be best?

Burf6 years ago
A general rule of thumb; if you can see the bearings, roller or ball, then you will need to grease them. If you can't see them and there is either a fiber or neoprene seal between the race and the bearings, you don't need to grease them.
As for grease, if they are for general purpose use, just use regular automotive bearing grease. If they are going to be used in wet locations, use a marine grade bearing grease.
A lot depends on the size of bearing you use. Don't overpack them with grease either, me, I'd've used shielded bearings which are effectively sealed.
NachoMahma6 years ago
.  The link takes me to a generic bearings page, but I'd use automotive wheel bearing grease for most wheel bearings on a car/motorcycle/motorbike.