They've stood up for a few years on the packed snow trails, but since I've taken to running the mountains (when I can), the coiled metal has gotten pretty bent out of shape.
Amazingly the rubber hasn't broken considering the abuse, but they have become pretty misshaped and I'll need to trust them not to fail on an icy mountain top.
A few years ago when I mostly ran paved bike paths I had something similar to Yaktrax that fit over my shoe, but these had machine screws and as I recall they worked like a charm on the glare ice on the local, paved bike path.
I decided I would make my own but these would be permanent.
I have a pair of Saucony ProGrid Razors that are still in really good shape and stricktly worn during foul-weather, so I thought it would be fine to "screw-up" these shoes.
I used #8 3/8 inch Sheet Metal Screws
I purposely left the center of the shoes without any screws, the tread is still in tact and the outside has some obvious screw locations.
I used Hex-head screws – they “bite” the ice much better than screws with a smooth or a curved head.
Screw Shoes work just fine on roads. It may wear the screw heads out a little faster but the screws are cheap enough not to worry about it.
It's not original idea but it's a trick that has served me surprisingly well on some very icy situations. You won't even know you have them on.