We just returned from two weeks in Paris and had a great trip using many of Rick's suggestions. However, we had trouble with the bike ride along the Seine Promenade which is described in the latest edition of Rick Steves Paris. The book mentions the cobbled section of the route near the Pont des Arts (page 533). We found this cobbled section of the promenade to be too difficult to travel on a bike. It is not just cobbled, but the cobbles are large and irregular, and the paving surface itself is irregular, with many humps, depressions and slopes scattered along the way, as well as some narrow sections. There can be many pedestrians along this path, and the south edge of the path is fully open to the river with no barrier of any kind. We felt unsafe trying to ride along here and decided to walk the bikes, but wish, in hindsight, that we had avoided it completely.
I'm not surprised at all that you felt unsafe. We felt unsafe trying to cross the street as a pedestrian at the cross walk with a light, yet the bicycles on the street path who don't have to stop. It's incredibly dangerous along the Seine as you try to cross as a pedestrian while watching for bikes coming from both directions not required to stop and yet no place to safe for pedestrians to stop and wait? Wow was it an interesting experience for us as well this past spring. I only felt more at risk in Amsterdam.
I appreciate your report about your experience. Rick also suggests bicycling along the Appian Way south of Rome, but the very rough rocks and cobbles, plus swarms of pedestrians who didn’t seem amenable to sharing the roadway made it difficult. Either Rick’s experiences with these two routes were very different (maybe many years earlier?), or maybe he’s a glutton for punishment.