What sort of screw do you use to ride on ice tracks ?
Last winter, I've used this ice screws with new Innova Power Gear tires on my 86' 250R :
They are 4.5 mm diameter and 10 mm lenght.
The problem is that after 10-15 minutes, there was almost no scews on the rear wheels; for a 1:30 hour round, it's not great... and it was a 4:00 race on 3 rounds of 1:00 to 1:30.
So I did most of the race without scew and it's not really fun...
So have you got better solution than mine to ride on ice ?