I was poking around sheldon brown's site and found this:
By modern standards, the typical English 3-speed bicycle is geared rather high. Most have 46/18 gearing, which gives gain ratios of 3.83, 5.11 and 6.81 (50, 66, and 89 inches; 4.00, 5.28 and 7.12meters.) You can make riding a lot easier by customizing the gearing. 20 and 22 tooth sprockets are readily available, as well as smaller sizes for speed demons or small-wheel bicycles. It is also possible to modify Shimano cassette sprockets with a Dremel grinder if you need something bigger. This is not particularly difficult to do.