About Those Dustbin Fairings of the 1950s

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Kevin Cameron has been writing about motorcycles for nearly 50 years, first for <em>Cycle magazine</em> and, since 1992, for <em>Cycle World</em>. (Robert Martin/)

In response to my piece about “Interference Drag” one or more readers commented that the full frontal streamlining used by most roadrace teams in the 1956–57 seasons was banned (1) because the result looked more like fish than like the motorcycles that the motorcycle manufacturers wanted to sell, or (2) because streamlining was inherently dangerous.

I can certainly understand (1), both from a manufacturer and from a consumer point of view. The motorcycles we are familiar with do not look like fish. This is, I suspect, why Craig Vetter has not been buried in orders for his fuel-saving streamlined bodywork, and cabin two-wheelers such as Monoracer and Peraves have remained curiosities.  A cabin bike advocate at one time assured in many emails that a one-on-one shootout between a MotoGP machine and a cabin bike would be a walkaway for the latter, possibly with radio and cabin heat operating.

The claim that streamlining is dangerous is interesting seen in the context of descriptions by the late English rider Bill Lomas. His autobiographical book Bill Lomas, World Champion Road Racer gives us an insider’s view of 1950s GP racing.

In 1954 he tested with MV. “…they told me there was a race at Faenza and they were taking the badly streamlined Earles fork (leading-link) 500 bikes. The fairing looked like a big sugar scoop. The wind got underneath it and made the steering go very light. At the end of the long straight the bike was starting to get out of control, even in a straight line.”

As Lomas’ narrative continued, he said, “A bike that also interested me was a prototype fully streamlined 500 DOHC single-cylinder Guzzi…

“This went very well and seemed to handle OK.”

Guzzi was the pioneer in motorcycle aerodynamics then, using its wind tunnel to progress from an earlier “bird-beak” fairing with exposed front wheel to its introduction of full frontal enclosure in 1954.

Moto Guzzi V8 Grand Prix Racer. (Moto Guzzi/)

Prior to the TT, Guzzi factory rider Fergus Anderson asked Lomas to take over his entries in 350 and 500. On the 500 single he noted, “Normally when you shut off to slow down, [a] bike loses speed fairly quickly. The Guzzi streamlining was so efficient that when you eased off, the bike seemed to go quicker. This would take a lot of getting used to.”

A similar situation existed beginning in the 1970 for riders on fast bikes, when braking for the Daytona chicane while drafting another rider. This reduction in drag, if not combined with thoughtful riding, too often resulted in what riders called “being sucked into the chicane.” This meant that they braked at the usual place but, lacking the normal drag of a bike not in another bike’s slipstream, they arrived at turn-in with extra speed, ran off, and crashed.

Another thing came to mind. In the excellent book Handling the Big Jets, written by D.P. Davies, then chief test pilot for the UK’s Airworthiness Authority, he cautioned those transitioning from propeller aircraft to jets that they must always have in mind the “slickness” of jets, which lacking the drag of propellers slow much less quickly during the landing roll than propliners did. This could allow a less attentive new pilot to arrive at the far end of the landing roll with dangerously excessive speed. This is what Bill Lomas meant by saying that the lower drag of the 500 Guzzi’s full streamlining “…would take a lot of getting used to.”

Later he noted that conditions for the Senior TT were “very windy,” and that a following wind “…would speed the bikes up and make braking more difficult. Fully streamlined bikes were affected by crosswinds but as Guzzi fairings were wind-tunnel tested they were not affected so much as the flat-sided ones.”

On page 180 he presents a photo showing that the cross section of the Guzzi fairing (which enclosed the front wheel in the style of that time) was round rather than slab-sided; “I found no more adverse effect to side winds than with an unfaired bike. In fact, the most difficult bike from that aspect was the 500 Matchless Twin (G45).”

Guzzi had the advantage of being able to test in its own wind tunnel (its interior shown in photos pages 229, 230, exterior page 259) which supported the test article on a central post that may have been capable of stability testing at yaw angles other than zero.

Moto Guzzi’s wind tunnel. (Moto Guzzi/)

Why rehash all this history when relief from such antique boredom is just one click away? Because it shows that Guzzi could engineer stability into a full frontal fairing in the 1950s, and that its competition often did less well.

At the end of the 1957 season, when Guzzi, Mondial, and Gilera pulled out of racing as the attractions of small cars ate into their sales, the FIM adopted the rules that continue to define the appearance of sports and racing motorcycles today: full exposure of the front wheel, complete visibility of the rider from both sides and above, and no streamlining forward of a defined vertical plane (originally through the front axle, but allowed to creep forward a few inches since 1958) or behind the rider (subject to interpretation by the technical director).

Was front wheel enclosure in the later 1950s a factory-only unobtainium anomaly? A photo (from Mario Colombo’s Moto Guzzi—the Complete History from 1921, page 83) of the 350 start at the 1956 Monza GP des Nations shows 28 starters, of which 21 are on bikes with “dustbin” full-enclosure front fairings. Guzzi pioneered their use in early 1954 and no team or rider wants to be left behind.

Colombo’s book notes on page 92, “In a short space of time all Grand Prix motorcycles, even those privately owned, sported a dustbin fairing. Not all were scientifically designed like the Guzzi models, which were tested in the wind tunnel, but the advantages were considerable for everybody.”

The front of Moto Guzzi’s V8 Grand Prix Racer. (Moto Guzzi/)

He later notes, “At the end of 1957 dustbin fairings were abolished by a new regulation, since the steering difficulties at high speeds were really considerable…”

Yes, they were—at least for MV’s “sugar scoop” fairing.

Are today’s 220 mph MotoGP bikes paragons of stability? No—high drag force near top speed creates an overturning torque that reduces weight on the front, resulting in uncertain directional control, especially at the US GP at CoTA, where undulations in the fast straight add to the effect.  This has been a principal reason for the adoption of downforce winglets in that series.

The bottom line is that I suspect that if motorcycle fuel economy is one day regulated or the limited range of battery propulsion requires it, the FIM’s late 1957 ruling will not remain the last word on motorcycle aerodynamics. Can we really believe that the last 65 years of aerodynamic research has nothing useful to contribute to the motorcycle?

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