Gravel Machine or classic Randonneuse: For bikes with wide tires, the 650B wheel size makes so much sense. The smaller wheels require fewer compromises in frame design, and your bike remains nimble despite the larger tires. Choose between our smooth all-road and our knobby dual-purpose tread. Either works great on pavement and smooth gravel. The knobbies come into their own on loose surfaces, in mud and snow. With Rene Herse tires, the only limit for your adventures is your imagination.