That is a cone bearing hub, the axle is bent. Your cheapest option is likely just replacing the whole wheel for less than $50 new if you look around. Back when I was a Buyer for shops a decade ago, a cheap hybrid style rim brake wheel was around $20-$25 at wholesale cost and retailed for $40-$50. I had to spend around $1k to get "free shipping" with that one. If not the thing can cost a lot to ship on special order and you'll pay for that. A larger shop that is ordering $1k+ weekly or biweekly form the major distributors is likely to sell it cheaper. Some small shops stock these things, but they take a lot of space for bad cash flow in most circumstances. If you know where to look for bikes people trash, a wheel like this is pretty easy to source for free. Like in the chain of shops I worked for, we were given throw away donations all the time. I wouldn't have used this option unless you were homeless or obviously destitute, but I had a stack of bike stuff under the main shop from people's donated bikes. Most were junk for one reason or another, but I used a cordless impact to disassemble them quickly and bin most of the parts. Most of that stuff went into building frankenbikes that the shop staff rode around town or gave away to the homeless, and for fabricating parts of my makeshift eBay product photography studio.
In many areas a quick cruise around residential areas will yield trashed curb bikes with a usable wheel.
While I don't doubt your expertise, can you explain how a bent axle causes this? In my mind this can't happen since the axle doesn't spin.
I do have a small bike shop near me, I might ask them for parts. There is also a similar build 5 speed wheel at my parents', maybe that has a hood axle.
Yeah it doesn't seem intuitive, but the bearing inner race is likely the hardened axle and follows the curve. It is a very common problem on cone bearing hubs, and it is the most likely culprit. It is impossible to say for sure without being present and taking it apart to see. I could be wrong. I have not worked as a bike mechanic where I have a ton of direct experience with these specifically. I can fix anything when present or on the road, and have extensive experience with cars, hot rodding, CAT/Case/John Deere heavy equipment, metal fab and machining, not to mention PCB design/fab and FreeCAD/3d printing... Not trying to brag, I'm just adding context. I make mistakes all the time like any human. I have only ever had to replace one bent axle in a rear wheel in my life, but I've seen issues mechanics had in passing, and been tasked with tracking down a replacement for them dozens of times. To my best recollection, the only reason for this kind of wobble was a bent axle. Always be skeptical though. "Mod" means nothing to me. I'm just the janitor.
It can happen if the bearing wears out. It has to be occasionally cleaned, regreased, and sometimes needs new rubber seals, or just replacement. Friction-related heat can definitely warp an axel housing. If it’s bad enough the wheel will seize. I wouldn’t be too surprised if there was also lateral wobble in the wheel.
A cross-threaded cassette might also produce this effect.
That's gotta be the freewheel/freehub itself.
Depending on type, you may be able to pull it apart. I'd bet that it's the connection between freewheel/freehub and the actual wheel hub.
Looks like I gotta get a tool to get the freehub out. It's one of these right? And see. And am I right that this could cause me to not be able to adjust the derailleur properly? Or do I have more problems?
That's to remove the casette from the freehub. You'll likely need a big hex key to remove the freehub from the wheel and it's going to be on tight. To open the freehub itself you might need another special tool for. I made one myself from an old socket that I ground away leaving just two opposing studs.
Every single freewheel does this, and it's not an issue.
The freewheel bearings don't line up exactly with the wheel bearings. This is always the case to some degree, because the interface between freewheel and hub is a non-precision thread.
It might look weird when freewheeling, but once you put use the pedals, freewheel and hub are rotating together, negating this wobble.
Maybe the end of the axle? This definitely looks weird
Axle
I've asked about this exact same thing before and the answer was that there's nothing to worry about it. My bike has been doing this for 2 years now and it doesn't seem to be affecting anything. Shifting works fine and all.
I think this might actually not be my main problem, but a tight cable. Shifting 6 -> 5 yields a different position than 6 -> 5 -> 4 -> 5.
