Just down the street from the shop was a group of German Rocket Scientists (no joke, one a colleague and co-worker to Werner Von Braun) and Physicists so Earl gave them his Girder and to quote Robert Di Nero who said to Billy Crystal “Analyze This” they were off to do their thing. To be “Certified” is to have your work, techniques, and knowledge, periodically tested by independent labs to make sure that the airframe you just welded together doesn’t come apart on the pilot and crew in mid-air. Being a Certified Aircraft Welder, he was familiar with and believed in the value of testing. Now that Earl had updated the classic and proven girder designs it was time to see how his new model worked. The new design also added components for disk brakes so the end result was lighter, stronger, visually cleaner looking, and a more safe Girder that helped make the Durfee Girder the one to have and to ride. His redesign also included four hidden, internal adjusters, that could be firmed up for fast riding or adjusted back for a smoother ride. Since 1970’s motorcycles were larger, faster, heavier, and more powerful than the old models that had come before, Earl brought the materials and processes he had learned from his years in R&D and redesigned the girder to handle the bigger loads and higher speeds by using things like aircraft alloys and T.I.G. Some of the old girders had flaws from the limits of materials and processes available in the 1920’s, 30’s, and 40’s, but by 1968 things had changed and we where in the middle of the “space race”, with all the knowledge and new materials that brought.īut even with the flaws, the good, far outweighed the bad because there are so many great things about girders, some ahead of their time, which convinced him that this was the way to go if you were after a good looking, incredibly strong, light weight and smooth riding motorcycle suspension. The Metallurgy and welding processes fields in which he had studied, worked-in and knew, had supplied him with the knowledge and tools to bring the girder design up-to-date. (2.) Earl had spent the last 15 years working in the R&D labs for two well known aircraft and defense contractors, building by hand, the prototypes for the Polaris and Minute-Man missiles. Earl saw that “Road” and “Stress” tests on these old girders pointed out the strengths and weaknesses of the designs. (1.) By 1968 the popular girder design which was used by Indian Motorcycle Company and was the preferred front suspension design used by the majority of the European motorcycle makers had seen a lot of bad roads (or in some cases, no roads and even bomb craters, motorcycles were used extensively in both WW-1 & 2) and many, many years of hard use. You see the better part was easy for Earl because of two big factors. It all started back in 1968 when Earl Durfee picked up an old Indian Scout Girder and knew he could do better. For more info, visit our disclaimer page.Ĭopyright 2014-2022 more information contact Paul Durfee at or call 50. This site participates in several affiliate programs.
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Related Articles: Motorcycle Frames and Suspensions Wide Glide Conversion How To Polish Aluminum Motorcycle Parts Motorcycle Quotes and Sayings Properly designed and constructed, they will handle as good, if not better, than any other motorcycle front end.
Pound for pound, they will deflect less than other types of front suspensions. Girder front forks were used on motorcycles for many years. Generally, average trail length on a motorcycle front end is between 3-1/2 to 6 inches. Too much or too little makes a bike hard to control.
The importance of trail is often overlooked. Trail is measured in inches, and should always be a positive number. Rake is measured in degrees, which means the larger the angle, the further out the front wheel will be.įront-end trail is the distance between a vertical line from the center of the front wheel's steering axis, to where the tire makes contact with the ground. The angle of front-end rake is formed between the frame's neck and a vertical line. In 1948, a Vincent Black Lightning (Black Shadow racer) with a "Girdraulic" front end set a new world record of 150.313 mph at Bonneville Salt Flats.