Blast From the Past: Specialty Files—1988 Trimble Carbon Cross

The 1988 carbon fiber Trimble Carbon Cross was quite the head jerker back in the day. It's still one of the most recognizable frame designs ever created.

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Editor’s note: This edition of “The Speciality Files” first appeared in Dirt Rag Issue #148, published in April 2010. Word and photos by Jeff Archer.


A short trip through the early history of the bicycle shows that there are very few new ideas in the world of two-wheeled human travel. Each evolutionary step brings with it both progress and problems. In the 1870s, the pedals of the ordinary (high wheel) bike were attached directly to the front wheel, so the speed was limited by the size of the wheel. The bigger the wheel, the faster you could go, but the wheel size was limited by the rider’s leg length.

By the mid-1880s, chain drive eliminated this problem since different sized sprockets would multiply the rider’s efforts. Chain drive also allowed a myriad of frame designs to come onto the scene since the wheels could be made smaller. Many frame designs were tried before most manufacturers adopted the familiar diamond frame. One of the alternative frame designs was the cross frame, which used a main backbone that traveled from the handlebars to the rear wheel. The pedal assembly was then hung from this backbone. With all of these inventors working during the 1890s, somewhere around two-thirds of all patent applications were bicycle related. These patents included such things as suspension, aluminum frames, anatomic saddles, clipless pedals and derailleurs. Sound familiar?

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Often these early inventions would pop up, become popular and then slowly fade away. Years later, the same idea is often tried again, usually with better materials. Our feature bike illustrates this point. Remember the cross frame of the 1880s? The design reappears as the 1988 Carbon Cross mountain bike frame by Brent Trimble. The material has changed from steel to a carbon composite, but the basic design is the same. Advantages of the design include a low standover height, elimination of chain slap as well as a subtle suspension effect. Problems include an offset crank to clear the frame, difficult rear brake mounting, custom front derailleur and bottom bracket flex. This flex often resulted in cracked frames, which was fixed with an additional bottom bracket brace in the later Inverse 4 Trimble frames. This bike also features the one-piece composite bar and stem combo designed by Brent’s brother Richard, aka Roo.

trimble-bar-stem-combo

I wonder what the cross frame of 2080 will look like? This bike, along with more than 400 others, can be viewed at First Flight Bicycles in historic downtown Statesville, North Carolina. If you can’t visit in person, take a virtual tour at www.mombat.org.

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We’ve published a lot of stuff in 26 years of Dirt Rag. Find all our Blast From the Past stories here.

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