Why are the bearings behind the spool only shielded on one side? Wouldn't a fully shielded bearing make more sense? They are sealed and lubricated for life. They are used in many industrial applications. Your thoughts?
Fishing reel spool bearings required very light grease , re-lube often . How ever on some reel like Dam Quick spinning used for salt water I prefer stainless steel bearings with double seal . Most bait casting spool bearings I prefer with one side open or no seal . It is up to you to decide what bearings to use
Water will eventually work its way in there, somehow-someway. A double shield might hold it in longer than a single or no-shield set-up. For me the best solution is to check periodically and at the same time see the inside. I prefer no shields, especially on a conventional, where the bearing sits in a cup(a cup holds water).
The bearings with rubber seals are great at preventing water ingress, but you lose a bit of free-spinning action compared to open or metal-shielded bearings.
Some bearings are shielded on one side, for spinners I always put the shielded side toward the rotor. Some have no shields, some have them on both sides.