My studded tire experiences and why I settled on metal screws from inside the tire.
The first set of studded tires that I did I used sheet metal screws from the outside. This was on my bike when I lived in a small town They worked great for the streets which always had at least a few cm of packed snow-ice on the roads. They had great grip and I really liked them.
When I moved to a larger town that would occasionally have bits of bare pavement showing in the winter I noticed that the heads of the screws were wearing down way faster than back home. I also quickly noticed that I would have much more grip on the hard-pack and ice than on the pavement.
This is because the metal screw heads were the only parts contacting the road and the friction coefficient between steel and pavement is MUCH lower than the friction coefficient between rubber and pavement.
The next set of tires that I made I used wood screws. I did not make pilot holes so it was sort of hit and miss for whether the screw came out the center of the tread. If I was not happy with where the screw emerged I would back it out and try again. This ended up taking more time than if I would have done the pilot holes ahead of time.
The screws stuck out by about a cm and they looked MEAN! I had to remove the side screws on my back tire even before I rode on them because they would hit my frame. I got the bike outside and got on. The screws just folded over and I could hardly get going. I pumped my tires up to 60psi to see if it would help with the folding and it did but the tires still felt terrible. when I rode around a snow covered loop it felt like the tires were actively trying to pull me backwards. I did not bother testing them out on pavement and walked over to the hardware store to buy shorter screws.
When I dismantled my failed tire I noticed that many of the lugs were ripped half off from the crews pulling so hard on them. I re-used the tire but put the new screws on different lugs. I first tested out the tires with the new shorter screws on a skating rink and they had AMAZING grip… but the super pointy studs quickly wore down even before testing what they would do on pavement. I tried them out on a clear patch of road and they felt a little bit squirreley but the grip was not bad. The screws only lasted about a week before becoming short rounded and mostly useless.
The next thing I tried was regular metal screws (like what I used in the tutorial). They provided almost as much grip as the brand new wood screws but held their point much longer. Their grip on hardpack and ice was quite good and the handling and grip on dry pavement was improved. These lasted the rest of the winter and showed little wear compared to the other systems I tried.
Halfway through the next winter the studs were starting to get a bit worn so I replaced the screws on the back tire with self tapping style metal screws. I was expecting improved grip and increased drag due to the fresh screws but only noticed the improved grip. The new studs would bite into the ice and prevent slipping but the lack of threads on the ends stopped them from sticking to the ice. I then replaced the screws on the front tire as well and noticed that my grip was about the same as when the other screws were new but there was less rolling resistance even when compared to the slightly worn screws.
Those screws lasted for two years until I stopped riding my bike very much in the winter anymore after switching to a unicycle for transportation.
On a unicycle I have used the self taping metal screws, regular metal screws and made a chain.
So to sum it all up here are the pros and cons I found with each setup.
Sheet metal screws from the outside of the tire:
Pros - Excellent grip on harpack and good grip on ice. No increased risk of pinchflats. Easy to install.
Cons - Wears quickly on pavement, Horrible grip on dry road surfaces. possible to loose screws.
Possibly the best choice if there is no chance of a hard surface that is not covered in snow and ice
Long screws
Pro - Looks cool
Cons - Utterly useless and waste of time. Wrecks your tire, won’t roll well, and dangerous.
BAD IDEA
Wood screws
Pros - Excellent initial grip on ice, better than the sheet metal screws on pavement.
cons - Wears out quickly, feels a bit odd on pavement, very sharp initially, could be dangerous. Slight road suck (drag)
Regular metal screws
Pros - Last longer than wood screws. Good grip on hardpack and ice. Good handling and grip on dry pavement.
Cons - Slight road suck/drag
Self tapping metal screws
Pros - Lasts the longest of all the screws/studs tried. Chisel point cuts into ice without getting stuck: reduced drag. excellent handling on hardpack, good handling on dry surfaces.
Cons - Can be hard to find in the right length
Best option for a variety of conditions. Also works well on wet/frozen wood.
Tire chains
Pros - looks cool, you aren’t putting screws through your tire so you don’t need a dedicated winter tire
Cons - less grip than studs, more expensive, more finicky, takes more time and planning, additional war to your sidewalls, harder to make.