Joe Dever (of Lone Wolf fame) also wrote a short post-apocalyptic series (4 books).
The first book has now been put online by Project Aon.
You are Cal Phoenix, the Freeway Warrior, champion and protector of Dallas Colony One. A murderous gang of HAVOC clansmen, led by the psychotic Mad Dog Michigan, are bent on destroying your fragile colony as it crosses the wastelands of Texas on the first stage of a life-or-death exodus to the California coast. These bike-riding clansmen are a formidable enemy: armed, cunning, and extremely dangerous, capable of launching a lightning raid at any time, day or night. You will need all your wits about you if you are to defend your people and reach your destination intact!