Helmets for european heads

Do you mean the Protec shop on Phan Dinh Phung in Phu Nhuan? They have bigger sizes and certainly can fit many European heads like mine.

If Protec etc do not have one big enough, you might be in trouble elsewhere too. Other brands are worn my Europeans too, of course, but how big do they get?

I buy mine in Andes - there is one on Nguyen Thi Minh Kai.

I have a huge head and no problem.

My wife and I bought Andes helmets. Mine came from the shop on NTMK opposite the ReU, but (rather ironically for the OP), they didn't have one small enough for my wife. Instead she found one at a shop on the corner of Tôn Thất Tùng (IIRC) that fit, but had an awful design. Solution? They just switched the foam insert with another shell with a more tasteful design. Moral of the story is that there are a range of sizes out there, just keep looking. And don't always trust the sales staff, they rarely know their stock.

Andes on NTMK is the place to go. There are many sizes, styles and prices of helmets there. More importantly, they are real. Do not buy from the street, supermarket or fake Andes stores.