We’re seen a few ENVEs in the workshop lately, all with a similar problem, and all needing rebuilds. It seems that the first ENVE factory built wheelsets (or at least with factory supplied build kits) used an internal alloy nipple supplied by Pillar from Taiwan. The nipple was made from very soft aluminium, and corrodes due to some electro-conducto-trickery stuff related to being on a spinning wheel, and insulated by the carbon of the rim. The problem effects Road and MTB, and even the new Smart ENVE System wheels are not immune.
So what happens? The nipples corrode badly, and in a short time (some of these wheels were less than 18 months old) pieces of the nipples break off and bounce about inside the rim!
Lesser cases have just seen the corrosion so bad that wheel truing and re-tensioning is impossible as the nipple is effectively bonded to the spoke by the corrosion.
We have been advised that ENVE have changed the spec and supplier of internal nipples, so more recent factory builds should be fine. If you have an earlier set, and are experiencing this problem, get in contact, we can rebuild them for you.