Dude, CAN YOU READ??? http://www.aluminum.org/ANTemplate.cfm?IssueDate=09/01/2004&Template=/ContentManagement/ContentDisplay.cfm&ContentID=7648 Honda CRF250R Lest Yamaha garner all the credit for its aluminum motorcycle technologies, it should be noted that rival Honda has an equal appreciation of the metal’s design possibilities. The company recently completed development of the fourth-generation aluminum frame on its acclaimed CRF250R motocross model. Almost a decade after the debut of the first aluminum CR frame, Honda engineers continue to marvel at the metal’s design versatility. “Many riders seem to think that aluminum frames are bound to feel [stiff], but the CRF250R’s frame has been tuned to offer a very natural feeling,” head designer Eiji Adachi says. “By adding a bit of thickness here and trimming a little bit off there, we have balanced lightweight agility with frame rigidity. Aluminum has a lower specific gravity compared to steel, so these adjustments are easier to achieve than with comparable steel frames.” One of the great advantages to working with aluminum, Honda notes, is that designers can add or take away material to add strength or flexibility in specific areas. In the case of the CRF250R, the main spars of its frames are rectangular in cross-section, which permitted Honda engineers more design latitude than that available to round-tube-steel fabricators. That allowed Honda designers to vary the thickness of the top and bottom sections of the box, vis-à-vis the sidewalls, simply by specifying a change in the extrusion dies. This helped make the frame members resistant to up-and-down flex while still allowing side-to-side resilience—both in precise increments. Honda engineers also took advantage of aluminum’s “tunability” to incorporate into the frame a forged aluminum steering head. The most visible distinction of the new frame are the main spars connecting the steering head and the swingarm pivot. These lightweight aluminum extrusions are shorter, narrower, and feature thicker walls than Honda’s third-generation aluminum frame. The upgrades to the frame change its “flex characteristics” to create a chassis that feels softer on bump impact and improves cornering over previous designs, Honda says. No doubt those are qualities that any enthusiast of motocross—where jumps of 100 feet and cornering at 40 mph are not uncommon—can appreciate.