I used to have a Performance M303 from the early 1990s, which is a fully rigid mountain bike with chromoly frame and a weird aluminum fork. When I exchanged its Panaracer Smokes (knobbies) for a pair of 26" 100psi Tom Slicks my life changed. Even though the bike still had flat bars, it was my favorite bike to take to charity rides and long mountain climbs (I lived in Idaho Springs, Colorado at the time). It was better than my road bike (which was a Trek 520 touring rig) but the only thing is that it looked funny with the skinny (1" or 1.25", I don't quite remember) Tom Slicks. But then whenever I wanted to ride on dirt or up a trail all I had to do was switch the tires again. It was by far the most useful bike I've ever owned.