Tim Isaac made very few bikes under his own name. Certainly well under 1000. Most were built in Denver CO. He started out working by himself and later had a helper named Jock. I can't remember Jock's last name. Jock died prematurely from a heartattack after a bike race. This had a profound effect on Tim's decision to get out of building under his own name and securing employment with the fledgling company Trek. Tim's frames were well made and most were built with fastback seat stays with a hidden binder bolt. Tim used to be an employer of mine and remains a pal. Tim also was an accomplished bike racer.
Curt Goodrich
Minneapolis, MN