Reassembling rear wheel hub I have a ten year old decathlon cheapo bike and I wanted to take out the axle out of the rear wheel to see if I could replace it with a quick release mechanism and also learn a bit about how it works (the bike is cheap and not important). I undid a few nuts until I could take out the large axle bolt but when I did, out fell a load of ball bearings from either side.

I don't think I'll be able to reassemble it and a lot of the parts are rusty and probably need replacing but I don't know what to replace them with and like I said, ideally it would be quick release.

As far as I can tell the assembly is a freewheel cassette. Then there was this large bolt going through the wheel with two nuts and another threaded item I cant identify either side. Inside there were the bearings each side with a washer like cover. But they seemed only to be held in place by the presence of the bolt.

Edit: The bike is a rockrider 5.0 from about 2010 or so.
Yes, that bolt was the closing side of the ball bearings, your current axle is probably a "cup and cone" hub.

You opened the cup, so the ball bearings that where rolling on the cone just fell off.

You have to replace them (same diameters and possibly same hardenss ...), clean and grease all the parts (rusty and not rusty, it does not really matter).

Finally, you can replace the axle with a quick release skewers, but it must be of the same (internal) length as the one you are replacing (130mm, probably).

Giving the exact bike model or at minimum a picture of the wheel&amp;hub may help us help you.