This past Spring, I fulfilled a longtime ambition by traveling to Lisbon, Portugal. I took my folding Brompton bike with me, ready to explore. I found parts of Lisbon fairly hospitable to bicycle travel, but there were parts that were downright scary. Some sections had hills that were steeper than those in San Francisco. And then there were the cobblestone streets and tiled walkways. The cobblestones made it nearly impossible for my narrow-tire bike to navigate some streets, and the tiles, though lovely, could be extremely slick when wet.