[Otto]

Thanks, all, this is helping a bunch.

Ted, you got 73.6 mpg on your Dakar loaded as in the picture in the linky? That's really good! Have you looked into Madstad or similar adjustable screens? I've heard they're pretty good, adjustable to allow wind up the back side to relieve the pressure bubble which contributes to buffeting. I'd like to be able to cruise comfortably at 80.

What I have in mind are some subtle and not so subtle changes to a Dakar. As you know, its engine fuel management is excellent, but aero could stand some tweaking. My thoughts:

1. Remove beak, consolidate hand protectors, turn signals, mirrors into one airfoil leading edge D section-shaped unit only as thick as needed to protect hands from wind (and bushes during off road use). Much less stuff hanging in the breeze that way.

2. Add front fender which hugs the tire, has airfoil D section "horn" to fair the airflow past the fork. I did this on my BMW R1100RSL using a flat wrap piece of Corplast, as the gap in the front of the fairing and behind the fork is surely a huge drag source. With the Coro bent into a D section and taped to the fork legs, I got significantly better fuel economy and less buffeting even though this mod is much lower on the bike than the windscreen.

3. Teardrop sorta wasp tail fairing as top bag/rider backrest, instead of sleeping bag, tent, etc. just strapped on and hanging in the breeze. This tail fairing would contain cargo, and also house the turn and brake lights, as well as license plate. Remove the existing license plate holder.

4. Fairing and windscreen conceptually similar to Craig Vetter's Alcan fairing, to shield the rider's legs and torso, which aerodynamically are part of the machine and so must be faired.

5. Hard bags thinner and longer, and tapered and much less protruding into the slipstream than conventional hard bags. Touratech makes expensive aluminum hard bags which are functional, but are aero speed brakes. The same or greater volume could be carried with conformal and streamlined hard bags closer to centerline, with lower weight and center of gravity,yet also protect the bike in tipovers. The conceptual inspiration for this idea is conformal fuel tanks on fighter planes. When first used on the F-15, designers were reportedly shocked to learn the plane had lower drag with the conformal tanks than without.

6. Use tough, forgiving plastic for these mods, designed to take tipovers. That's how modern kayaks are made, to take major rock hits, bounce off, while retaining shape, strength, and beauty.

I like the BMW F650GS Dakar because it is a dual sport bike, mainly for highway use, but suitable for dirt or gravel fire and logging roads, crossing some streams, etc. On YouTube are videos of mc tours in the beautiful Altai Mountains of Siberia, and evidently the tour companies all use BMW F650GS Dakar bikes in this very remote and primitive area. So, I presume these bikes to be reliable and efficient.