We'll start with an image of the stock /5 frame and some thoughts by the preeminant chassis designer, Tony Foale: "The main "weakness" of the BMW series /5 /6 /7 frames is in the area of the SA pivot mounting. Side loads on the rear wheel will tend to make the upright tubes holding said pivot move fore and aft. This can largely be prevented by mounting a bracing tube on each side. These tubes can be attached to high up on the front down tubes or to the underside at the front of the mini backbone. At the rear I mount them above the SA pivot. Some others put the rear mountings below the SA pivot (see p182 of the Clymer manual 500-1000cc twins 1970-1979, October 1979) but the under side is better supported by the bottom rails which are tied to the rigid crankcase anyway. These tubes obviously need to be detachable for engine removal etc. and so the detail of the fixing can be very important to the success of the mod. I don't like the simple drilled flat brackets combined with a flatened tube end that I've seen. I've used mating bosses with one counter-sunk at 45deg and drilled and tapped, and the mating one turned with a male 45deg, the other side counter bored for the head of an allen bolt. These are mounted at right angles to the bracing tube and so the taper takes the main load and the bolt simply holds them together, as long as the bolt is tight then there is no slop, and I've never known the bolts to come loose. Another though less important frame mod. is to put a short bracing tube from the rear of the top of the head stock back on to the backbone, this will reduce some distortion under braking." – Tony Foale

The stock Type-247 "GUMMIKUH" frame was conceived, engineered, and developed with an image of the successful 1940s Norton Featherbed pictured clearly in the minds of the German designers. First renditions of the swinging arm frame were used on Factory "works-bikes", most notably, the RS54 Rennsport racers. This 1950 era, post W.W.II rendition, was then modified for production road fittings and usage, introduced to the public on the /5 series in 1969, and used with no appreciable structural, engineering, or design changes until the demise of the Type-247 in 1995. Outdated ? Ya think ? As horsepower, contemporary suspension components, capable brakes, and sticky tires are added to an old Type-247 chassis, the stock frame will certainly show it's age and weaknesses, flexing like so much cooked spaghetti, unwilling to cope with the additional stresses without rearing it's head in retaliation. Solutions would be forthcoming from most every source that sought to run the bike hard and fast.

The "Team Incomplete" frame: An extreme amount of triangulation is used and the lower frame rails eliminated. The engine is hung from the rear mounts, the upper trans to case bolts, and an added mount at the upper chaincase casting, about where the diode board normally resides. Gregor Halenda claims that this frame is lighter than stock:

Frame builder, Rob North, working with Udo Gietl and the Butler-Smith racing effort, started fresh with this very efficient design. Rob North had earned his reputation by crafting frames for such racing legends as Dick Mann, Dave Aldana, and Gene Romero. Apparently the BMW rendition was more successful in a twin shock version:

Rob North built a similar chrome-moly frame for the 745cc BMW GP bike campaigned by Butler&Smith, and ridden by Reg Pridmore. Rob North's frame deserves a couple of pages worth of pictures. Here's a few:

Details of the Rob North chassis:

More details of the Rob North chassis:

Sketch of the proposed "CRo / Lufthaptprojekt / X-frame ". Yes, the method in my madness – researching a frame-build of my very own. The design incorporates an extensively modified stock R80GS frame, with a good dose of Tony Foale's expertise as shared in his excellent book "Motorcycle Handling and Chassis Design", just a dash of Incomplete, and many lessons learned from Rob North. Randy Illg and the FRAMECRAFTERS team has crafted this design with the utmost precision, care, and expertise !!!. Follow CRo's progress starting on the "CRo / Lufthaptprojekt" page.

The CCP-TSS by CC Products was to be sold as a completed bike, a rolling chassis, or a kit. Apparently it never went on sale, a victim of liability pressures, and only one was ever built, Too Bad.

This frame, sold by HPN in Germany, is modified extensively for dual sport use. Although not designed for road or track work, it does address many of the same "weak links" of the stock unit. Neck stem and swing-arm pivot areas are reinforced with plate (areas in grey) to eliminate potential off-road breakage: