Not quite pre-30... but enough interest that I thought it might fit here.
WW2 Brit. Triumph with experimental "Pillbox" armor added. Allowed the bike to be used as cover with some armor protection. There is also a Bren on a swivel behind the armor. Clearly they made at least one by the period photo... not sure if this restoration is original or replicated off the photo. I can't believe they produced them.
Hitting a large rut or pothole could probably turn it in to a guillotine for your happy region... ouch. But in wartime, privates are expendable...
But the whole concept is just very cool! And the restoration is amazing for those who like military stuff.