Aero mods to dual sport or dirt bike, fully retaining off-road function

[Varn]

I don't see much progress as you might think. I had a 72 Triumph 650 Tiger (a twin cylinder with single carb, ignition points). It would get 60 mpg at 70-75 mph.

My current 78 Yamaha SR500 and 79 XT500 bikes get about the same.



I am not saying that these old bikes ride as well or are as reliable but the fuel mileage is very similar. These new machines should be getting 90 mpg stock.

[Grant-53]

Maybe I'm the eternal optimist but I believe an off road bike can benefit from air flow improvements. The overall shape would be similar to the Vetter Challenge streamliners but shorter and with more ground clearance. Remember Fred Hayes uses a KLR 650 frame for his diesel bikes. First is the material selection and I like aluminum composite bulkheads, ABS skin (0.060"), and 4130 steel mounting hardware. The nose profile should keep the bike from flipping when in Wheelie Mode. Brackets for auxiliary lighting and internal pockets for gear are useful. The leading edges of the rear bulkhead should have a radius at least 2.5-3.0 inches. This allows the rider to move on the saddle. The higher seat height may be an issue so have the upper part of the rear box hinged on one side like a lunch box. The rear box should be waterproof and allow cargo to be secured from shifting. A trunk light and a light gray interior color would be handy.

[andrenoites]

Cool bike you have there

[Varn]

The ground friction is magnitudes higher in an off road situation. Very little to do with aerodynamics. Not saying that their might be some improvements. To understand it better ride an off road bicycle and a road bicycle. Hills are 5x steeper.

About the best thing going with dirt bikes is that they are single cylinder and usually of small displacement and have good lower rpm torque, all good attributes for fuel economy. A far cry from the two strokes of my youth.

I still have two of my old road racers both 2 stroke twins. Both energy hogs but I love them.