Relationship between speed and cadence?
Speed is determined only by gearing, of which crank, cassette, wheel, and tire are components

Any 2 bikes using, say, 42t cranks with a rear 32t cog and 25c tires on 700c wheels at 90rpm will be going the same speed. Bike type and size, rider/bike weight, and even front wheel/tire size and crank length don’t matter. These other factors only effect how much power it will take to keep up that cadence with that gear combination.