I have a Hunt 4 Season Disc rim (rear) that has done quite a lot of miles and years. Was just changing the tyre when I noticed a metallic rattle and on further inspection it appears to be some sort of debris inside the rim extrusion. There isn’t a tyre on it and the rattle is definitely coming from the rim area when I hold the wheel and shake/rotate it. All the spokes are taut. There isn’t any visible damage and everything worked fine when I last rode it. The last maintenance I performed was swapping a valve core (not the valve) so most likely not that.
Any idea what it might be?
I’ve got an email off with Hunt to see what they think but I’m really curious as to what would cause debris inside the extrusion.
Since the unidentified debris is loose and rattling around inside the rim, maybe try removing it to see what it is?
To remove the debris (or at least, sight it), with the tyre left off, remove the entire valve assembly and rotate the wheel so that the valve hole is in the 6 o clock position. You should be able to, minimally, see the debris through the valve hole. If not, gently give the wheel a shake until the debris falls to the valve hole opening.
If it’s small enough, it might fall through the hole, otherwise, try using tweezers or a pair of long nosed pliers to carefully extract the piece.
Ok so in hindsight it was the obvious: Balls of dried sealant
In my defence I’ve never had this before and expected the sealant to dry into a latex film or something. Instead it seems to have made petit-poi’s size balls of dried sealant that are smooth on the outside and full of dust/dried sealant.
Really surprised how much noise they made given how easily they squished once removed.
Rattle removed, tyre on and inflated and less worried about some failed weld or aluminium swarf appearing in my rim.