As a 40 plus year pro motorcycle mechanic, almost 20 years of that as a motorcycle chassis specialist, I have seen the oem's go from loose, uncaged ball bearings (in the '70's and pre) to caged balls (in the 80's)to tapered roller bearings (in the 90's) BACK to caged ball bearings (presently) as standard equipment from the factory on new bikes. Talking about steering head (neck) bearings here.
Why is this, you might ask? I think, because they are idiot proof, and simple to install, and are very adequate if maintained.
I used to agree strongly with the commonly held opinion that changing to tapered rollers was an automatic upgrade and enhancement.
In my business we straighten frames, triple clamps and swingarms everyday. Current and vintage bikes, of all types and brands.
We take front ends off of every bike that we put through our frame jigs for straightening. I inspect, clean, grease, adjust and/or replace steering head bearings in bikes almost every day. We keep a range of inventory of both ball type and tapered roller kits that cover most common apps.
There are situations where we must use tapered rollers for reasons which I will not get into here.
We have learned a few things, we try to NOT have to use tapered roller bearings because:
First; if over packed with grease tapered rollers makes for lots of drag, too much. Just enough grease to keep the rollers and races from rusting and provide a little cushioning is all that is needed. NOTE; this excess drag can cause big instability in high speed straight line riding. WOBBLES
Second; we have learned that over preloading tapered rollers creates too much drag. There is a very critical, fairly finite point of adjustment to eliminate freeplay (clunk clunk) without creating too much drag. Target is no looseness and little drag. Too much of either causes WOBBLES at speed.
Thirdly; ball bearings seem to be idiot proof where, a little preload by way of adjustment and they are good to go. No finicky adjusting like tapered rollers require. Very seldom requiring follow up adjustments. Improper setting here causes WOBBLES at speed.
Fourth; no matter how diligently prepared and installed and adjusted, the tapered rollers frequently/commonly require a follow-up adjustment after things settle in, within about 50 miles on them. If this is not recognized/done, you get dents and beds at each roller(or ball) element beat into the races from the slight hammering from the 'clunk clunk' movement, this will ruin new bearings in a few miles. Guess what? WOBBLERS
Excessive amounts of grease on them provides absolutely no benefit.
I repectfully disagree with the belief that ball bearings are crude compared to roller types.
As far as I know almost all of the current ball type bearings in modern motorcycles are 'caged' ball types.
Well there you go, that is a little of what I know about steering head bearings and their affect on motorcycle handling.
BTW, there are many other reasons for motorcycles to wobble.
Solving handling problems for motorcycles is the heart of my business.