Interestingly, an idler can be designed to create much less of a side load than a belt. But unless you're looking at a EMT, chances are the idler you see pushes on the platter with quite a force.
This creates exactly the same problems for the main bearing that we have described in our previous post:
oil starvation, dry spots, poor stick-and-slap performance.
On the positive side, designing low diametric force idlers is easy. There's no need for extra moving parts, just a careful consideration of a drive geometry. Another approach is a Lenco-type drive (covered below) that doesn't create any side force at all.