The 50cc Kreidler
THE 50cc KREIDLER
SLONIGER
YOU don’t have to be a metallurgist to build a winning motorcycle, but vast light - metal experience certainly helps Kreidler stuff some 9 hp into a 50cc racing bike weighing no more than 130 pounds, and probably a fair slice less. This latest Renn-Florett has been raced successfully, winning both its first race and its first world championship run easily, since our pre-season notes, and the figures are more complete.
Kreidler even managed to overcome a natural Swabian reticence long enough to allow a few pictures of the bike without its fairing but they frankly don’t like to talk. They are very much aware that old racing firms like Honda and MZ have entered this new championship class, to sày nothing of the Suzuki and Derby, and are determined to defend their unofficial title from 1961.
Last season the 50cc machines ran for a European Cup that signified top dog in the class but didn’t rate world recognition. This season they have moved into the center ring, which explains the interest of such as Honda. All of these companies build lightweight road bikes in the 50cc division, or thereabouts, and motorcycle factories still believe that buyers read race results. Kreidler even goes so far as to name the race bike after their road machine, or Florett, though they have little in common outside of two wheels and two cycles. Renn-Florett simply means race Florett.
To answer the obvious question first, they are not for sale like the road bikes, even in limited numbers like the sport products of some firms. These are strictly test beds.
Kreidler carries this a step further by refusing to hire riders for racing alone. All four of their works men labor for the firm in other jobs, generally in the test department, and all four have to work on their own mounts. In fact Hans-Georg Anscheidt, the Europa Cup winner in 1961 and current point contender for this season, had to quit another firm and join Kreidler to get a ride. They have one dental student on the four-man list this year but he has to work there too, postponing his extractions for the moment.
Anscheidt is no small part of the Kreidler success story. This miniature champion holds lap records on most European tracks, in addition to his cup title. He is the perfect size for a 50cc racer; they have to feed him up to make the new 130 pound minimum in championship events. Despite the jockey size he is also a top man in cross-country trials which Kreidler contests too, though he won’t have much time for it this season.
As a development staff man Anscheidt knows the bikes from the metal to the track, has ridden them in wind tunnel tests, and can even keep the motors within the power curve, no small feat with a band that reaches all the way from 9,000 or 9,500 to 11,000, and twelve cogs to remember.
This box and its double-handful of ratios came to light recently. The rider has four gears controlled by a normal foot pedal. The fun begins when he starts to add in or subtract the two sub-steps between each ratio, using a twist-grip combination on the clutch side, in scooter or moped style. Going up isn’t so hard, they say, it’s remembering where you are on downshifts.
Actually, of course, no racer uses all twelve for any one corner, but they found the total necessary to have the perfect gear for all parts of a mountain course like Nurburgring, for instance. Kreidler engineers know their torque arc — it’s too small to call a curve — so well that they can predict the proper gear for every corner or rise before training, giving the riders a place to start. With only 50cc, keeping the power within its range is allimportant. Incidentally, only the works riders are allowed the full dozen. New men on test start with the straight four.
The new FIM rule on minimum rider weight makes it a little easier to find champions. At one time any applicants for a Kreidler saddle were put on a scale first. They admit it may be necessary to hire outside help if a super-star comes along, but as long as Anscheidt carries on it doesn’t seem necessary. To open the 1962 season he ran off and hid from the class, admittedly made up of his teammates. The first real test was the Spanish Grand Prix where he again stole the silver, hounded strangely enough by the untouted Derby. Such talent as Luigi Taveri and the new Honda got no closer than third.
At the recent Isle Of Man TT Races Kreidler had engine seizure problems and did not finish. The name of Dan Shorey was added to the team as a factory rider. It is interesting to note that the Honda and Suzuki machines were turning laps around 75 mph and obtaining speeds of 95 mph in the straights. It is a pity that Kreidler had troubles; the outcome could have been somewhat different. Time will tell.
Granting that Anscheidt and company know how to ride, we can take a little closer look at their mount. Until recently, Kreidler was highly reluctant to even take the fairing off in public — although a picture without it appeared in a Japanese magazine at the height of this secrecy campaign. Nowadays they are a little more relaxed. Part of the reluctance might be laid to the fact that they are relatively new to racing, have no race department as such, and build only one line of machinery — the 50cc’s that grew out ofmodels.
They aren’t really in the motorbike business and have no plans for larger models. The factory was founded sixty years ago as part of the metal industry, and second-stage metal work is still their main business by a wide margin. They take the raw metal and turn out tubing, sheet metal, and various special alloys for specific purposes. This is the experience that has paid such dividends in the bike. The firm makes some 400,000 spectograph analyses yearly, for instance, and up to a million metallurgical checks of one kind or another on the quality of their products.
In Renn-Florett terms this means they could strengthen various parts of last year’s bike and still hold the weight line at 110-130 pounds dry by using magnesium for such items as the brake drums, A gearbox housing and around the motor. The cylinder remains aluminum, with a hard-chrome bore in the Porsche automobile manner. The design is pure Kreidler, though the finished cylinders and heads are made by Mahle of Stuttgart. They were the first German bike to use this chrome cylinder lining.
Last year’s racing bikes had a highly distinctive, radially-ribbed head but it has been dropped this year. The first engine with the square cylinder and head were tried at the Eifel Race in Germany, where the ’62 model made its debut, and the design was as finalized as any race pattern could be. This was their first change in shape. The chrome-moly tube frames come from their metal experience too, and are bent of aircraft standard material.
The aviation references at Kreidler aren’t entirely accidental since their chief designer, Hans Hilber, started with planes. He joined Kreidler before the racing bike era and “more or less inherited this field,” to use their description.
Getting back to the two-cycle engine, Kreidler first tried a rotary valve design in June of last year. It worked and is standard now, after a full winter of testing. Actually the tiny cylinder has two such rotors, fed by a pair of special Bing carburetors that cost more apiece than a road Florett from the assembly line. That’s one expense of improving the breed. This engine has a bore of 40mm and stroke of 39.7mm to make 49.85cc, about as close as they can get to the border. They wind it to 11,000 for power and carefully duck all questions on output.
The only power curve released covers the pre-rotary race engine which offered 6.5 hp at the crankshaft. Some prodding prompted the guess of “maybe 8 hp” last season with the early model of the current powerplant. Some magazines guessed considerably more but it doesn’t seem likely. For 1962 — early part — a figure pretty close to 9 hp would be reasonable and doesn’t draw a firm denial from Kreidler. These are all honest ponies, remember. Taking nine as a base we get a hp per liter performance of 180.
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In addition to the rotary valve design, Kreidler admits to long hours on the bench obtaining what appears outwardly to be a straightforward extractor. They found the small engine excessively sensitive to the curve and length of the pipe, like all its peers.
Second winter amusement for the Kreidler experimental department, which is now in the racing business, was the fairing design. They discovered that five or six pounds of bike or rider weight doesn’t make as much difference as a proper bend in the streamlining. Using the wind tunnel at the technical college of Stuttgart they devised the optimum shape with rider aboard, gaining 25% in speed over an open bike. The final shape was created by making a fairing of fine mesh and covering it with a pliable plastic. This could be bent a little at a time to work out the best form empirically.
A Kreidler has been officially clocked as high as 75 mph with gearing for a road course, during the Dutch race, and the latest version would certainly top that. They find that spring rates are far more important to cornering times than even gearing or torque, since the chief problem is keeping the urge constant. The new bikes have adjustable spring legs front and rear to allow precise tailoring for each driver and circuit.
In the same manner, they run on special Continental race tires developed with Kreidler help for race 50’s. Avon also makes a tire for the class, incidentally. Ignition is by Bosch, including the platinum distributor points, but no firm actually supports Kreidler in the manner of most racing—because they don’t want it. The firm, now headed by the son of the founder, simply has an interest in small motors — apart from the benefit to their road line — and the current, and rather strong-minded, leader reportedly had an interest in two-wheel racing for some time before getting into the game with both wheels.
It hasn’t all been charged up to publicity. At the moment Kreidler uses the same grade of crankshaft in both the RennFlorett and the series model. Of course, they prefer to say that the normal crank is so sturdy it is race caliber, but the fact remains that the lessons learned haven’t been thrown away. The road bikes started with 2.2 hp, back in 1951 when the first Kreidler moped went on the market. Their top “sports” model now has 4.2 for the same capacity.
So far Kreidler has been doing quite well in the 50cc race field in Europe, but even on home ground we have rumors of another new contest bike. Meanwhile they have the rider with the most experience of the class per pound of any man going, two years of competition know-how, and maybe even more than 9 hp. They aren’t talkative people in Swabia, that portion of Germany around Stuttgart noted for its mechanics and workmanship. The silverware collection makes their case. •
