GRM (Grapevine Racing Motors) framed bultaco. These rigid frames were built by Bill Grapevine of Leon, Kansas during the U.S. trials boom of the late 60's and early 70's. Bill was also the creator of the GRM Trialsmaster. The GRM Trialsmaster was produced in Mexico by Islo motorcycles and was built to Bill's design and specifications. Very few were produced; but I have one with an extra engine as well. I would love to find one of these rigid frames for my extra Islo engine. Bill was also a pioneer in bicycle trials. He designed and built a 26"x24" trials bicycle for a young Ryan Young during his brief stint in competitive bicycle trials in 1986. Ryan later went on to be quite competitive in motorcycle trials competition.