A fabric is manufactured, woven from tape with a high resistance (carbon) core. All the warp tapes are connected together as one pole and the weft as the other pole, to a low power high voltage generator stepping up the voltage from a couple of AAA alkaline cells to a few thousand volts.

Garments are assembled from patches of such fabrics - since cutting and stitching will ruin the electrical continuity. The generator will be conveniently placed inside a pocket with the switch run out to a cuff for easy access.

You will put on a suit, hop on to that 135 mpg bike and, having arranged yourself comfortably, push the switch. The suit hardens into steel-like rigidity over the course of a few minutes.

Should you get forced off the road by some road hog in an ancient truck with zilch crumple zones, the armour protects you in a crash. Should the abrasions prove severe enough to rupture the electrical integrity of the garment, the charge leakes away and the suit regains flexibility within a few minutes.

When fully charged, the suit will store a respectable amount of charge, enough to electrocute you in an accident should the tapes contain metallic conductors. High resistance cores will ensure that any charge is dissipated slowly and that the discharge current is not fatal.

For additional tensile strength some of the tapes could be made of bullet proof vest material (kevlar).

In a really hard collision your relatives are spared the chore of mopping you up off the scenery. Suggested by [magnificat] &[SDG].