This is a complex sentence formed by one main clause:
- Its impact would have been modest ("its impact" subject, the rest predicate)
and two adverbial clauses, one of concession:
- Although the new, improved bicycle had appealed immediately to a few privileged women ... ("the new, improved bicycle" subject, the rest predicate)
and one of condition:
- ... had it not attracted a greater cross section of the female population ("it" subject, the rest predicate)
In grammar, the most usual thing for us to find is a subject (with one or more noun heads, depending on whether it is simple or compound) and a predicate (containing one or more main verbs, depending on whether it is simple or compound) in each clause (main or subordinate).