utoner34

If you have a hub (rear or front) with sealed bearings and they develop small play over time (you can feel the wheel when tightened with thru-axle still has lateral play),

do you risk of damaging hub itself if you dont change the bearings on time?

And can you recoignize this in any way or you need to change all bearings first, then if the play still remains, hub is a write off?

Iride01 

A little play won't hurt anything. A lot of play will be unlikely to damage your hub if the play is in fact in the bearings. But obviously if it causes rubbing or other interference, then YMMV.

So I'd go for little risk if you don't change the bearing on time. Because you'll probably be experiencing things that bother you too much before that time.

Don't judge the amount of play by what you see at the rim with respect to a fixed point nearby. That's a pretty long arm and will magnify a very tiny amount of play many times over. And if you can't actually see the play at the axle, then it might be something else.

Rick

If you can actually see the play, I would replace the bearings before they end up wallowing out the hub.

Andrew R Stewart 

For a rear hub/wheel there's about 3X the increase of leverage/play between the axle and the rim.

One of the really neat aspects of a cartridge bearing (be they radial or angular contact and ball or roller elements) is that all the bearing wear can be replaced with new ones. However any wear that the hub shell or axle sees isn't as inexpensively replaced. How would a hub shell or axle seat wear? By movement between the bearing and the shell or axle. More often seen with cranks/BBs then hubs.

How to tell if this added movement is happening? You take the axle out and look at its seats for uneven surfaces and the same for the hub shell (by removing the bearings from it). This will also let you test the no preload feel of the bearing (often an in shell bearing will feel rough/gritty with no axle in place and then feel smoother when pulled out of the shell, loosing that press fit preloading). Now you can decide what you think of the complete system. Very rarely will the axle or shell contact seats/surfaces be worn enough to need any remedy. And at this point of complete disassembly (so you can be sure of the various possibilities) replacing the bearings with new is a pretty smart idea (given their relatively low cost).

So the short answer is to just replace the bearings whenever you think it is worth it. Usually after the first few bearing replacements a rider will begin to develop their own service schedule and approach WRT when a bearing is replaced.

Al the above is assuming radial contact bearings, which are the vastly more popular type. If the OP has angular contact bearings then we need to know about the axial load adjuster and if it has been played with. Andy

grumpus

You can expect a small amount of play in any cartridge bearing that has had some use - it's not worn out, it's just worn in. Larger amounts of play that lead to noise or knocking in use and you should replace the bearing, otherwise the bearing seat might be damaged with further use. If the bearing seat is slightly stretched or worn you can fit new bearings with something like Loctite 638 which will hold the bearing in place.

redshift1

And bear in mind that brand new deep groove radial ball bearings have a clearance inside them, ranging from C1 ( least ) to C5 ( most ) specification if I remember correctly. Almost every new bearing I have unpacked from the box had an easily discernable clearance.

Edit : Thought about it some more and the clearance felt in a new bearing is not so much radial so with two new bearings installed some distance apart, it's unlikely to be felt as significant play at the rim.

FBinNY 

It depends on where the play is.

If it's within the bearing it won't harm anything else, and you can ride until it's bad enough to replace.

However if the bearing can move within the hub shell, which is rare, but can happen, you need to act immediately, if not sooner.