Right now I wear my regular glasses (actually, an old set of semi-wrap, flexible alu framed glasses designated for sport wear now) under a Dux Helm helmet which has a retractable visor.

The thing I like about the Dux Helm is that I can easily change the lens color for conditions, and quickly retract it back into the helmet if it gets dirty, or I want to ventilate more, the conditions change, or I want to safeguard it during transport.

It's not the coolest helmet for the hottest days, but is really a clever design, and affords me lots of flexibility without the risk and hassles associated with an expensive set of scrip shades; I'll never leave my helmet somewhere like I've done to $400 sunglasses! I don't take 'em off and leave 'em at a rest stop, or forget to pack 'em out, or need to find a place to carry my regular glasses, so it's a system that works great for me.

The only thing to be aware of is that the amount of space between the Dux Helm lens and your face is small, so wrap style glasses work best, and large glasses or those with protruding temple pieces at the lens might not work at all.

Check it out:

http://www.duxhelm.com