Originally Posted by Duragrouch

(bold above) With greatest respect for you, you have more experience than I, but the above is not true. Internal cartridges are two ball bearing assemblies (I think deep groove radial contact) or one ball and the other roller bearing, like the SKF, with no adjustment possible. Maybe internally they are not cartridge, but races right on the spindle and cup and cone, but the key is, not adjustable.

The external cartridge bearings are different, they are angular contact on both sides (like cup and cone, only enclosed), and readjusting out slack and adding preload is a simple matter of loosening the left crank arm clamp around the splines, retorque the end cap to 6-13 lb-in, retighten the crank arm clamp, and you're done. (Usually when I do this, after loosening, I remove the left arm and retract the right spider a bit, clean any dirt out from the interfaces, reassemble, then torque.) It's a brilliantly simple and very effective system. I've only had to retorque once so far, about 6 months into use (what a surprise, same interval as internal cartridge starting to loosen a bit), not since. I think the first slack may come from burnishing in the bearings, removing the grinding marks. Having no slack and the proper preload, loads a lot closer to 180 degrees of balls per side with radial load, rather than only a couple with slack. Other bonuses with external: More space for more bearing balls, closer to crank arms so radial load is reduced, stiffer and lighter spindle, and as mentioned, backwardly compatible into BSA BB shells. I wish I had invented the system, it's one of those things I look at and just marvel in its brilliance. Only negative is some off-roaders feel taper spindle (or internal cartridge in general) is better in mud, seals recessed, unlike the contact surface between crank arms and external bearings, dirt might grind there; Sounds valid.

Aheadset stems are very similar in how they adjust preload on a headset, much easier than the old style with big open end wrenches, not having to deal with thread backlash. Maybe the Aheadset (came first) was inspiration for the Hollowtech-II system.