I'm just gonna say, I don't always wear my riding jacket, but I do always wear my Nolan N102 Modular. I figure my face skin is more important than my back skin (though I would rather keep all of it, that's why I try to ride with as much gear as possible...)
I also have a cheap full face Chinese and a Nolan N100 Modular helmet for any ladies who might want to ride (unfortunately the Chinese helmet seems to fit the ladies better... So I just don't tell 'em it's a cheap Chinese helmet
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)
As for experience with a cheap Chinese "V-CAN" modular helmet, I will never buy one again. I suffered a get-off at about 40mph into a ditch, and according to a witness the helmet had flipped open and came off my head before I even hit the ground. I suffered a broken nose and bad cut over my eye (4 stitches) because of this. Fortunately the gods were smiling on me and besides some road rash on my back and a scar on my ankle, that was all I suffered. Though I never want to spend 5 hours on a spineboard ever, EVER again.
We took the helmet home and put it back on my head, and with just the lightest pressure on the chin the (all plastic) locking mechanism popped open, the face went up and the helmet slipped forward and off my head, even with the chin strap cinched down uncomfortably tight. I'm guessing the wind caught under it and flipped it up and off when I went flying through the air.
I contacted V-Can and they sent me a new NON-modular full face helmet (their top-of-the-line model, about $100 more than the original modular I had crashed in).
SO, lesson learned: Don't buy cheap Chinese modular helmets. My Nolans have a 100% steel locking mechanism that won't flip up no matter how much pressure you put on the chin.