I lost half a dozen
@User259, just during the first couple of weeks, over the 2 tyres, then no more.
They are easily replaced by sliding them into a fully inflated tyre with the aid of some washing up liquid. Tip kindly shared by
@SatNavSaysStraightOn.
Email Schwalbe, they will send you a handful of spare studs for free. The tyres work a treat btw.