Yesterday I felt something strange when I was on my way home ….. today I found out !
About 6 nipples came out of the rim !
The nipples seemed worn, although “normally” they are so tight that movement isn’t possible.
But the fact that they look worn doesn’t mean they are able to flip through the hole in the rim. So I guess that due to the brine that is used in the Netherlands to get rid of the snow in wintertime; the rim is damaged or at least too much affected. I renewed a few nipples and put a small ring between the rim and nipple to prevent it from slipping through the rim-holes again.
In the meantime I’ll ask velomobiel.nl for advice 😉