What you are dealing with is two genes that have different locations or loci on the chromosomes. Because of this, a spider cross pinstripe has exactly the same odds of producing spinners as spinner cross normal (which are both 1 in 4).

This is different than say, a super pastel (or super anything) or BEL for example. Those two genes share the same location so a super x normal is 100% pastel, for example. But a pastel x pastel is 25% normal, 50% pastel, and 25% super pastel.

Did that help?

JonV