Screw shoes are my absolute favorite method for gaining traction while training through the Winter https://www.superiorballscrewrepair.com/. They open up safe running on hundreds of miles of snowmobiles and frozen lakes in the area, allowing me to run over ice without much more danger than running on dry pavement. Here’s how to make yourself a pair for just a few dollars.
I usually use #6 sheet metal screws. Don’t get anything longer than 1/2´´ or else they will probably poke through your shoe and into your foot. With most shoes, you can use the half inch screws in the heel without any trouble. With my trail shoes, which have a very aggressive tread, I use the half inchers throughout the entire shoe. With my road shoes, I tend to use 3/8´´ screws under the ball of my foot.
I tried using half inchers with an old pair that already had about 500 miles run in them, and the screws did go through. Running slow wasn’t a problem, but any sort of fast running and I could tell there were screws pushing into the bottom of my foot. If the soles of your shoes are really thin, then you might be able to put some screws around the outside edges of the shoe, but it might just be better to get smaller screws (such as 1/4´´ sheet metal screws) or else move onto a different pair. The shorter the screw, the more likely that it will fall out while you are running and you’ll have to replace it.
I like to use sheet metal screws because they have a good bite around the outside edges and I can put them into the shoes using a socket extension on my cordless drill. Trying to screw the shoes in by hand is certainly feasible, but it’s a lot of work and will make you rethink your decision to have traction on your run. With a drill, it literally takes about a minute and a half to put in all of the screws in one shoe.
Sheet metal screws are also pretty cheap. If you get them in packages of 20, they’ll probably be about 10 or 12 cents per screw, but if you get a larger package then the cost goes down to a couple of pennies per screw.
When you put the screws in, you are literally screwing them up and into your shoe so that the sharp point is towards your foot. If you use rounded screws, you are just going to make your run more difficult and it will defeat the purpose of putting screws into your shoes in the first place.
When you put the screws in, put them at the lowest points of your shoe. If you are running in a road shoe it may not make a big difference, but trail shoes tend to have a more aggressive tread and you want to make sure that the screws are the first thing to hit the ground. Putting the screws between the treads doesn’t really make much sense.
How many you put in is up to you. I like to put 3 to 5 screws into my heel, and then 5 to 10 screws into the forefoot section of the shoe. A friend of mine has 19 or 20 screws in each shoe. The best method is to start by looking at the wear pattern on your shoes and to begin by installing the screws where your foot is naturally going to hit the ground first or where you push off with each stride. Those are the points where you are most likely to slip anyway. Start with a smaller number and then add more if you feel that you need them.