Ceramic bearings

[Mick F]

Cups as well as cones can be replaced.

I've scrapped a couple of Shimano hubs due to cups being worn. Shimano don't show cup parts in their drawings. Not sure even if you can get the old ones out?

Dunno about Shimano hubs, but I can't see them being any different to others.

The hubs are aluminium.
The cups are steel.
They therefore are pressed in .................... so they therefore can be pressed out. A flat blade screwdriver and a hammer works well for driving them out.

I modified a steel shaft cut off from a screwdriver. I heated up one end to red hot with a blowlamp, and bent it over then let it cool slowly. I filed the end to form a sharp edge and curved it to fit closely inside the radius in the hub to connect with the inner face of the cup.

I heated it it again and quenched it to harden it.
It works beautifully for hub cups, and I've even use it for removing headsets races from head tubes.

Buy a complete hub.
FAR cheaper than the all the bits individually.

[Brucey]

...I've scrapped a couple of Shimano hubs due to cups being worn. Shimano don't show cup parts in their drawings. Not sure even if you can get the old ones out?

they certainly do come out, but it ain't easy! Because they are not designed to come out (in the normal run of things) in several shimano hubs you need to do something brutal (like weld to the thing) in order to be able to knock it out. This works for the scrap ones but the others you need to get out some other way. So yeah you can do it but it is often easier just to rebuild the wheel on a new hub.

FWIW the #1 cause of a failed cup insert in a normal shimano hub is some kind of maintenance issue; if you keep the hubs properly greased and adjusted the cups don't wear out, not for many, many tens of thousands of miles.

However I would say that some shimano front hubs for disc brakes, the bearings are under an abnormally high stress. I have a feeling that these hubs may be more prone to failure and problems.

cheers

[Mick F]

Why aren't Shimano hubs so easy?

Campag ..... both old and new ............ come out ok without fuss.

Steel cups in alu hubs.
What's the problem?
They went in, they must come out.

[Brucey]

Why aren't Shimano hubs so easy?...

in quite a few designs, you can't get a punch on the back of the bearing insert, because the hole in the hubshell is smaller than the hole in the cup... simples..

In many more recent designs (with a fat central barrel) there is no problem, but you need to remove the cups from another hub etc...

cheers

[Mick F]

Sorry, you've lost me there.

Go back to Old Campag.
The centre of the hub was very narrow and the bearings wide, but you could still remove the cups.

[Brucey]

there was a recess cut into the aluminium part of the hubshell in those hubs, so that a tool can be used against the back of the insert.

In a lot of other hubs, there isn't; just a plain bore in the hubshell (say 11mm dia) and a hole in the cup that is larger than that. No purchase, hence welding (or something) required!

cheers

[Mick F]

Ok.
I bow to you knowledge once again!

Here's a shot of the tool I made maybe 30years ago.
Works a treat for hub cups and headsets.
5mm thick and about 10" long.
(pardon the mixing of metric/imperial!)

[Steve O'C]

I've wondered if ceramic ball bearings might wear a cup or cone smooth if slightly pitted.

I have seen it suggested in another forum that one way of treating pitted cones is to fill the hub with copaslip instead of grease, ride it for a few miles and that might wear the cones smooth again. Does anyone think this would work?

[Mr Evil]

I have seen it suggested in another forum that one way of treating pitted cones is to fill the hub with copaslip instead of grease, ride it for a few miles and that might wear the cones smooth again. Does anyone think this would work?

Copper is soft, so I doubt it would have much abrasive effect. It might work sort of the opposite to that though, with the copper adhering to the surface, filling in any gaps (which is how it works as a lubricant in high temperature/pressure bearings).

[Mick F]

Copper is indeed soft, but it's very very tough.
You try sawing through a chunk. It'll blunt your hacksaw.

[Mr Evil]

Copper is indeed soft, but it's very very tough.
You try sawing through a chunk. It'll blunt your hacksaw.

Pure copper is easy to cut. There are copper alloys that are much harder, but still a lot easier to work with than the sort of hardened steel that bearings are made of.

[Brucey]

copper and most copper alloys cut very easily. The main problem is that the blade will clog. A few alloys work-harden very quickly (which can cause jams) or have hard particles in them which can wear the blade at a rate you wouldn't expect.

BTW I have seen the results of running a hub that was 'greased' with copper ease and it wasn't at all pretty. If your bearing surfaces are a bit rough there are any number of other better things you could do than that.

cheers

[Dave W]

Apology for off topic but Zondas can be difficult to change tyres on - just saying.
Make sure you do a practice before going out on them. One good point is that the tyre is unlikely to roll off the rim if you have a puncture.
Sorry I can't help with bearing question.

Strange, I have Zondas with Gatorskins and never found them difficult to change tyres no need for levers to put them on either.

[pete75]

What is the supposed advantage ? Are ebay "bargains" even round ? Many cheapo ball bearings are not.

They are from an established bearing factor. http://www.airebearings.co.uk/index.php Such businesses tend to know about bearings and usually rely on supplying local engineers/garages/ individuals etc for much of their trade. I doubt they'd have been in business for 25 years if their wares are as you describe.

[Mick F]

If your bearing surfaces are a bit rough there are any number of other better things you could do than that.

We had someone on here some few years ago who professed to mount bearing cups (somehow or another) onto a fast drill and smooth them off with emery(?) or something.

No doubt it works with cups too ................ if you can get them out.