I've similar gearing to MacB's hybrid on an old steel tourer - I'll sometimes use my "top" gear of 52x12 on a downhill if the way ahead is clear and I know the surface is good - just to give me a bit more momemtum going in to the next rise.
Doug - are you native French speaker by any chance?
Est-ce qu'il y a des forums comme le CycleChat en Francais?