Originally Posted by Myosmith

The old Trek 700 series framesets make great gravel grinders, that's what mine is. You can squeeze up to a 45mm tire on depending on the tread and brand. Schwalbe Smart Sam 40mm work great and give you enough clearance to shed a little mud and debris. They are extremely tough and comfortable framesets and can be had inexpensively. If you find a Trek 730 of about 1990 vintage, you have a treasure with the full cro-mo stays and fork. The 700s of that era had a cro-mo main triangle but hi-ten stays and fork.