Hello, I am a complete newbie to road bikes and bicycle building. So far I have been happily riding my three speed Raleigh Caprice daily around London, and it's a great commuter bike. But I want to be able to do longer and harder rides outside the town, and with my dutch style bike it's a struggle.

I bought a second-hand Reynolds 531 with 27in tyres and thought I could fix it up to use. However currently it is a struggle pedalling on it, because I am assuming the crankset to cassette gears ratio is not good for me. The bike has a single 48 tooth 165 Sugino crankset.

My initial thought was changing the crankset to one with less teeth. But I would prefer a single crankset like it currently has because seven gears is plenty for me, as I never plan on climbing mountains with this bike. Unfortunately single cranksets are an expensive rarity. I am now considering changing the gear cassette instead.

My questions are: is a single 48T crankset too hard a crankset to keep and would a 42T like my initial thought be better? If I was to keep the 48T crankset, what gear cassette would you propose I match with it? I mainly plan on cycling around the English countryside that is hilly, but has no mountains. Also I am not very interested in high speeds, but rather in long distances. Also if it makes a difference, I am a woman and not particularly tall.