It is very difficult to find a used tandem in the right size. There are fewer tandems (than singles) and having to fit two people means more combinations of sizes, so it is a double whammy. When I was looking last fall/winter, I found the middle range ones in our sizes harder to find than the odd ball ones. Don't know why. Don't give up, broaden your Craigslist searches to a bigger area, stay on top of ebay, check the various tandem places you can find on the net.