How do they keep the bearings from skipping over the rear gear/disk? That disk and driveshaft would have to be extremely stiff to avoid flexing, especially in l

How do they keep the bearings from skipping over the rear gear/disk? That disk and driveshaft would have to be extremely stiff to avoid flexing, especially in lower gears where the contact point is further out, and it looks like just a couple millimeters of flex will give enough space to skip.