Complex sentence: He started racing on motorbikes in 1981 and after minor success, he moved on to single-seater racing cars and progressed steadily up the ranks to the International Formula 3000 championship by 1989, where, although often competitive, he never won a race.
Split into simpler sentences: He started racing on motorbikes in 1981, and after minor success moved on to single-seater racing cars. But although he had progressed steadily up the ranks to the International Formula 3000 championship by 1989, and was often competitive, he never won a race.