it's for the 2th regiment of the " carabiniers-cycmistes "
the pennant is after war
surname : the black devils
2e régiment de carabiniers-cyclistes (Belgique) - Wikipédia
You sure it is not from the premiere cycliste, which later became the chasseur ardennes? Or something like that. I only say this because the number 1 is on the top left of the pennant.