Write the first paragraph of a blog post describing the appeal of gravel bikes in the bay area.

For many years, cycling has been a staple in the bay area. Its temperate climate, easy access to nature, and bike-friendly sentiment have fostered a steady growth of interest in the sport, especially with the rise of COVID creating a shift toward distanced outdoor activities in recent years. Traditionally, cycling has had three modalities: mountain biking, road biking, and cyclocross. Recently, a fourth modality, gravel biking, has had a rapid rise in popularity.