I passed my test on my brother's CD175, it was the first bike I ever rode on the road, after learning on a 2-speed Puch (I think?) 50cc moped across the fields. Those were the days. CD175 was a terrific bike, had a lovely combination of induction and exhaust noise. Was a little naughty on it in the end, dropped in on a very sharp bend in Copnor, Pompey. My excuse was that it had square section tyres.