The problem with mine was that a batch of bearings did not get greased correctly when produced, bike shops ought to be aware of this and the shop you bought your bike from should replace these free of charge.
Halfrauds did mine and it's been fine since.
edit
But just read this
Yes before I started ranting about how cheap I thought they were I figured I would give them the benefit of the doubt. I'm not sure I like all this carbon techie stuff. Give me some steel any day. I cant take them back as I ordered the bike from miles away and I really can't be arsed. What tool do I require to overhaul them myself?
The problem with mine was that a batch of bearings did not get greased correctly when produced, bike shops ought to be aware of this and the shop you bought your bike from should replace these free of charge.
Halfrauds did mine and it's been fine since.
edit
But just read this