Matt.....these strips are rarely across both lanes like those stupid 30mph zone ones which seem to warn you about the speed limit 'as you are leaving the village'? These only sit across one lane, around 5 or 6 strips but often come in sets of three (15-18 total), about 25mm wide but with varying thicknesses, usually around 10mm which is a hefty thwack in yer front tyre at 60mph. They are of a high grip substance but cause the tyre to momentarily leave the ground so in the wet whilst braking and leant over they are going to make a motorcycle very unstable, in fact an unexperienced rider could lose control with dire consequences! I guess they are cheaper than warning signs!!
There are some really bad ones on the A623 between Peak Forest and Stoney Middleton. Where tight esses go through a steep dip. A sign saying very slow or dangerous bend would be fine but no, not in Derbyshear!