Axle - rear hub and washer thing a bit loose I have a rear wheel that has needed work 3 or more times in around 3 years (of not very regular riding) and I'm wondering if something is especially wrong with the setup on this FUJI road bike.

A few years back I reworked the axle on the bike - put some grease in it and set it. Later it had come very stiff. I opened it up and bought some cones to replace it - fairly chewed up.

This year I took it to a cycle-hobby shop as the wheel was wiggling like out-of-true, but no one portion of the wheel consistently rubbed. Sure enough, they say it needed bearings, now it trues up perfectly and all good?



Now, after a few rides and a few months, I'm seeing it is obviously loose and furthermore the little round washer was coming loose. Pushed it in and rode a bit, and this part is still not completely fitted in as I can push it in a little.



What is that part called, and is it safe to run with that a little loose? Is just tightening the cones and tightening/loosening likely to fix this for good or... for another year at least?

The chain goes forward just slightly when freewheeling but apparently that is supposed to be normal? Not sure if it is in any way related.
The round washer-like piece that's loose is a metal dust cover. It keeps debris and water out of the bearings. On some hubs they're pressed into the hub shell and on others they're pressed onto the cone, which is what this looks like. Having it be loose is consistent with replacing the cone with one that wasn't quite the right diameter to mate properly with the cover. There's not much leeway there.

The usual procedure for transferring the dust shield is to cradle it with a vise or socket and very gently tap the old cone through and the new one on.

You don't really want it to be loose because they're the hub's main line of defense against contaminants. If it's rotating around freely it may get damaged as well, and be unable to press into place on a new cone.

Replacing cones is a careful business of finding one where the ground part matches the profile of the original one well, making sure the ball track is falling in a good spot on it in practice, in this case ensuring it has the right major diameter for the dust cover, and then making sure the spacing of the hub is right when you're done. There are some in-depth treatments out there of this, Barnett's Manual has a good one, but it's a fairly big topic. Repeat problems with the hub coming loose, rapidly accumulating wear, etc are likely outcomes of the match not being great with the profile of the new cones. The balls may be making contact in an awkward spot of the curve or off of it completely. An extreme case of this may make the wheel not usable. It could be a good idea to look at the cones and see how they're wearing.

It's also possible that the cones were a good match but the cups are damaged and causing repeat loosening. If so that's likely to keep happening but take a long time to be an acute problem.

The chain behavior is probably some dryness or gumminess in the freewheel and not related.