How often (in miles) would you expect to have to tighten rear axle cup and cone bearings.

[gbb]

Damaged threads on the nuts/axle?

Had exactly this. it seemed to adjust up ok, soon to lose adjustment. Turned out the axle .threads were damaged

 

[classic33]

Had exactly this. it seemed to adjust up ok, soon to lose adjustment. Turned out the axle .threads were damaged

Come across it when fixing bikes for others. Repairing the repair.

 

[weareHKR]

A friend brought me his 1-year-old Carrera MTB yesterday with the same issue, only the front wheel, in the frame, it was rattling bout like a prick in a tophat!
Anyway nothing was loose & it was all clean inside, the bearing was good, cup/cones were fine, I've clean it out regreased it & set it up, bobbed it back in the dropouts & it feels fine... I'll see how it goes!

 

[faster]

A friend brought me his 1-year-old Carrera MTB yesterday with the same issue, only the front wheel, in the frame, it was rattling bout like a prick in a tophat!
Anyway nothing was loose & it was all clean inside, the bearing was good, cup/cones were fine, I've clean it out regreased it & set it up, bobbed it back in the dropouts & it feels fine... I'll see how it goes!

Did you lock both cones securely? If so, then fear not!

Proof: General Theory of Relativity (adapted). I have discarded the ideas that the axles will slowly stretch under tension, or that the hub itself will narrow with use, or that the (ball) bearings will wear with use. The only way longitudinal play can develop in a hub is if the cones move away from one another. If the cones are both securely locked this cannot happen.

No need to see how it goes. Sit back and relax, safe in the knowledge that the hub you fixed for your friend will not develop play.

Proven using General Relativity, no less. Sounds good to me.

 

[Ajax Bay]

@faster
I thought you/we had "agreed to disagree".
Though @classic33 's idea of thread failure of the axle or locknuts is another possibility - that would allow the cones to move apart.

 

[I like Skol]

Thread failure? Not really, but has rung a bell somewhere deep in the dusty recesses of my mind. Isn't there two very similar threads employed for bicycle axles, one metric and one imperial? They are very close to being the same but while one will fit on the other, it doesn't fit both ways. The problem is that the bigger threaded cones will fit on the undersize axle and looks ok, until it is tightened, at which point it can slip.

 

[Lovacott]

A friend brought me his 1-year-old Carrera MTB yesterday with the same issue, only the front wheel, in the frame, it was rattling bout like a prick in a tophat!

It's been about week since I started this thread and already I have a slight rattle if I push my rear wheel left to right. I've cleaned and rebuilt the whole assembly quite a few times and I am wrenching up the lock nut as tight as I possibly can.

It's sweet for a couple of days and to be honest, unless I had checked this morning, I would never have known that there was a bit of play. I reckon I could ride for another thousand miles before the bearing became problematic. That aside, this should not be happening.

My personal theory is that because the standard 21 speed MTB has three on the front and seven on the back, the seven on the back means that the drive side bearing is closer to the centre of the axle than the non drive side bearing (and therefore bears more of the weight). This in turn will induce wear.

When I was younger, five on the back of a freewheel system seemed like a lot. Now, all of the cheap bike models have seven on the back freewheels with the better brands opting for cassette setups.

 

[Ajax Bay]

the drive side bearing is closer to the centre of the axle than the non drive side bearing (and therefore bears more of the weight). This in turn will induce wear

What element of the system do you think is wearing? The cones? The cups (hub)? The bearings? Are you having to retighten both locknuts or just the left hand one?

 

[Ajax Bay]

How's the hub? Has it stayed OK these last 10 days?