Hey ladies and gentlepeople, I have a quick question. First, background:

Okay so my brother fell in love with an early 2000s department store Magna Mountain bike... now please hold your horses before saying "throw it out" or "those bikes aren't worth repairing" it's his bike, he got it for cheap, and he's rather sentimental with that mass-produced, overweight, behemoth. Anyways...

The rear wheel suddenly jammed (he won't tell me more cause he doesn't know much more about bikes) and he had to call our roommate Maggie to pick him up a few nights ago.

So I get to inspecting his bike this morning only to see the wheel is whack-out-of true, many of the nipples are rusted and edgeless (that's no problem, easily replaced and adjusted), a lot of the spokes are loosey-goosey (I've never serviced his bike), the axle is bent (also easily replaced), and worst of all for his tight budgetness, the LOCKRING on was destroyed and not even attached to the hub. The outer edges are intact, but the threads look like someone took a grinder and a torch to it and smashed it in a vise (see photos).

My question is, and sorry about the length of this question, will I have to buy a new hub or casette? Or do you think it's possible to find a lock ring that will fit the stock wheels of a Magna Excitor (I'm highly doubtful, just in case the sarcasm doesn't translate over the internet). The cup reads "TANDEM"





I can try to supply more info if you need, but here's what I got:

36 spoke, 15 gauge
26" wheel
26 X 1.95 tires
7 speed casette (don't worry, it's got a three-speed crank if you were starting to think it was somewhat sensible)

Anyways, I appreciate any help on the topic regarding next steps. I have the know-how, I just need to know how to proceed with this one-part dilemma.