@Marie, George S. has a good idea; you can also raise the stem using these spacers (or a variation of these) to raise the height of the stem. The Sondors bike was not really designed to be a totally upright design like a city style bike, if that's what you're looking to do but some spacers or a different stem that fits in the same way as the original (aka George's solution) but with a more vertical angle might be a solution. Send some pics! and Welcome to EBR!