Some comments on the parts pictured above. I don't have a frame to put them in yet.
The ZTTO headset looks well made, with sealed cartridge bearings that are easy to replace. My only concern with the headset is the crown race. It doesn't seat well in the lower bearing, and there's a rather large gap between the crown race and the cup. I fear this will collect dirt rapidly.
The Goldix hubs also have sealed cartridge bearings. The freehub pulls off with a little effort, giving easy access to the star ratchet. I was able to pull off one end cap of the front hub by hand; I couldn't figure out how to get the other end off.
The ZRACE bottom bracket looks OK, but I am concerned that the bearings may be too small for the loads of a 220 lb (98 kg) rider. The seals between the bearing cups and the spacers look kind of small as well.
All the bearings moved smoothly with finger pressure. (Unlike the Shimano Deore XT front hub in a wheelset I bought a few months ago - that hub had a bad bearing ball out of the box.)
All of these parts had excess grease on the bearing faces. I wiped off the grease as best I could. There was quite a lot of grease around the star ratchet parts too. I know the ratchet itself needs grease, and the ratchet half inside the freehub has to move in its splines, so the splines need grease too. But there was grease everywhere inside the cavity. I cleaned off the excess grease and applied some Slickoleum directly to the ratchet surfaces and the splines.
These components don't have much in the way of external seals. That's the biggest difference between high end components and these bargain parts. Most of my riding is in dusty terrain in California. So I'm concerned about dirt getting into the works, and sticking to all that excess grease.
There were no instructions with any of these components, of course.
