Biking the Crosstown Trail, San Francisco
I highly recommend the Crosstown Trail, a grassroots-developed 17-mile hiking route across San Francisco that strings together existing paths through parks, urban greenways, stairs, and the bits of road needed to connect them. There’s an associated bike route that combines parts of that trail with parallel road routes where it would be impractical to ride (though even this route also includes some carry-your-bike staircases and narrow dirt paths). Just imagine, you can experience all of this within the city limits: ...