In message , Clive
George writes

Define "best". Longest lasting? Smoothest running? For some
applications, the cheapest are the best choice because that's all they
need.

Also, assuming you've decided you want eg the longest lasting ones, how
far up the price/performance curve are you actually prepared to go? If
the normal ones are a fiver, are you prepared to pay 100 quid for ones
which may last twice as long?

(and a side question : I know ball bearings come in different qualities
- do the sealed ones have the same range, or are they rather more
standardised?)

Bearings are sealed depending on their application and intended
lubrication. eg. an electric motor bearing might have the dirty
*windings side* sealed and the clean side open for grease lubrication.

Internal construction has not cropped up yet and my bearing book is over
in the workshop, steel cages, brass cages, nylon/plastic, fully filled
etc. etc. AFAIR the numbers give the o/d, i/d, width and abutments and
the letters refer to the cage and sideplates.

regards

--
Tim Lamb