A few things first:
1. Bearings play a role in your reel smoothness, but more bearings doesn't mean the reel is better.
2. Bearings have no role in casting on your spinning reel.
3. There's usually only two bearings on your baitcaster that would affect casting. Both work together to hold your spool while it's spinning.
So you're thinking about upgrading your bearings and want to know what it could do for you.
1. Better distance
2. Easier start up
3. More consistent cast
4. less back lashes
5. replace your worn bearings
Now before you take the bearings off your brand new reel and install the latest *insert your favourite brand* Abec X bearings, I would suggest you to get familiar to your reel while it's stock to understand the limits of your current set up. On top of that, many spool bearings come greased up from the factory and that's a big nono. You could realize a performance gain after you flush out the grease and properly oil it!
So how to choose a bearing. Aside from asking for recommendations, there's not much we can do to help us choose because there's no way of measuring the performance of a bearing. So you might ask, isn't higher Abec rating better? In simple terms, yes. But you have to understand that Abec rating merely means that the bearings conforms to a certable level of tolerance! It does NOT tell you that one bearing is smoother, more durable or spin faster.
There are many who speak of ceramic bearings and say they spin better, this is a false conception. Given that all else is equal, the ceramic balls does not provide better spinning properties than SS bearings. Ceramic balls do give you some benefits such as longetivity and heat resistance.
Here's a food for thought, both of these bearings are made by Boca, both are Abec 7 rated and both were sold simutaneously at a certain point in time. As you can see below, it's obvious that they are two different bearings (cage, ball count, ball size..etc)
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That's all for right now. We'll talk about bearing maintenance and oil another day.
