The Imme R100 was a lightweight

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

made by Riedel AG from 1948 to 1951. It is noted for its simple and innovative design with many advanced features. With low cost and technical innovation, the R100 sold well, but reliability problems and low

profit margin Profit margin is a financial ratio that measures the percentage of profit earned by a company in relation to its revenue. Expressed as a percentage, it indicates how much profit the company makes for every dollar of revenue generated. Profit margi ...

s resulted in warranty costs driving Riedel AG into bankruptcy. The advanced specification of the Imme R100 caused it to be highly regarded. The R100 was one of the motorcycles included in "

The Art of the Motorcycle The Art of the Motorcycle was an Art exhibition, exhibition that presented 114 motorcycles chosen for their historic importance or design excellenceSawetz. "The Art of the Motorcycle is curated by Thomas Krens, Director of the Solomon R. Guggenh ...

" exhibition at the

Solomon R. Guggenheim Museum The Solomon R. Guggenheim Museum, often referred to as The Guggenheim, is an art museum at 1071 Fifth Avenue between 88th and 89th Street (Manhattan), 89th Streets on the Upper East Side of Manhattan in New York City. It hosts a permanent coll ...

in 1998 and is on permanent display at Barber Vintage Motorsports Museum.

Concept, design and engineering

Motorcycle engineer Norbert Riedel recognized the need for a simple and economical light motorcycle during Germany's recovery from the Second World War and began to design one. By the summer of 1947, a

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype ...

frame had been built and tested. The spine frame was made from 40 mm steel tubing, as were the steering head, the single-sided front fork, and the single-sided

swingarm A swingarm ( or swinging arm), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of the ...

. The wheels were interchangeable, and were mounted from the left on stub axles attached to the suspension on the right. Riedel developed the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...

at the same time. This was a piston-ported two-stroke

single-cylinder engine A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, motorized bicycles, go-karts, all-terrain vehicles, radio-controlled vehicles, power tools ...

of capacity. The engine was cast in light alloy around the cylinder liner, and had an integral cylinder head. The

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

was suspended on only one side. The power output of the engine was at 5,800 rpm, which was considered a high output at the time. Contemporary engines of comparable size typically made about , and 4.5 PS was expected from 125 cc engines such as those used in the

DKW RT 125 The RT 125 was a German two-stroke motorcycle made by DKW in Zschopau in the 1930s, IFA and MZ in the 1950s and early 1960s, and DKW in Ingolstadt in the 1950s and 1960s. "RT" stands for , . In the 1930s DKW pioneered the Schnürle two- ...

and the later Hoffmann Vespa. The

transmission Transmission or transmit may refer to: Science and technology * Power transmission ** Electric power transmission ** Transmission (mechanical device), technology that allows controlled application of power *** Automatic transmission *** Manual tra ...

had three speeds with no neutral position; a mechanism held the clutch open when the motorcycle was at idle in first gear. First gear was positioned in the middle of the shift pattern, with second gear below and third gear above. The engine and transmission were mounted together on the swingarm in front of the pivot axle at the bottom of the spine frame. The near-horizontal engine and transmission together as a unit formed a "power egg" style which would later be used by Benelli and Motobi. The tubular swingarm also served as the exhaust pipe. Behind the pivot axle, the swingarm, the reinforced rear fender, and the supports for the rear carrier formed a triangular structure which supported the rear spring. This suspension system allowed a long suspension travel and a soft spring rate. Test rides on the complete prototype began in December 1947 and showed that the combination of long travel and soft springs needed

damping In physical systems, damping is the loss of energy of an oscillating system by dissipation. Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. Examples of damping include ...

. Friction dampers were added.

Production, marketing and demise

Norbert Riedel registered Riedel AG in 1948. He moved his facilities from Muggendorf to

Immenstadt Immenstadt im Allgäu () is a town in Oberallgäu, the southernmost district of Bavaria, Germany, in the German Alps. First mentioned in a 1275 administrative tract, it was granted town privileges in 1360, which makes it one of the oldest towns in ...

and began production there in June 1948. It is widely believed that the name "Imme" came from an abbreviation of this location, and that the Imme's "bee on wheels" logo came from "Imme" being a dialect word meaning "bee". However, it has also been suggested that the name came from the motorcycle itself resembling a bee, or from the engine sounding like a buzzing bee. Imme R100 engine left side

The Imme R100's light weight, relatively powerful engine, and long travel suspension made it popular in motorsport; this, along with good marketing and low pricing, led to strong sales. The management of Riedel AG expected high sales volume to offset the low profit margin. A basic Imme sold for 775 Deutschmark without battery,

tachometer A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a axle, shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrat ...

, or centre stand. Passenger accommodation was an optional extra, as was a spare wheel. Initially, Immes were all painted oxide red. In 1950, a better-equipped "Export" version became available for 850 Deutschmark with a battery, an electric horn, a centre stand, a speedometer, a more comfortable seat, chrome plating, pinstriping, and a choice of colours including lime green and gloss black. Production of the Imme R100 had gone up to 1,000 per month and, by the autumn of 1950, more than 10,000 had been sold. Imme engines were also sold to Fritz Fend, to power his Fend Flitzer

invalid carriage Invalid carriages were usually single seater road vehicles, buggies, or self-propelled vehicles for disabled people. They pre-dated modern electric mobility scooters and, from the 1920s, were generally powered by small gasoline/petrol engines, alt ...

s. These replaced the

Fichtel & Sachs ZF Sachs AG, also known as Fichtel & Sachs, was founded in Schweinfurt in 1895 and was a well-known German family business. At its last point as an independent company, the company name was Fichtel & Sachs AG. In 1997, the automotive supplier w ...

engines used in earlier versions of the Flitzer. However, the Imme began to develop problems, especially with the single-sided crankshaft bearings and the

freewheel image:Freewheel en.svg, Freewheel mechanism In mechanical engineering, mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission (mechanics), transmission that disengages the driveshaft from the driv ...

for the

kick start Kick start is a method of starting an internal combustion engine (usually that of a motorcycle) by pushing a ratcheting lever with the rider's foot. Kick start mechanisms were almost universally a part of motorcycle engines before the mid-1970s ...

er. Riedel corrected the problem beginning with the Model D version, which had a conventional crankshaft with two bearings. However, the profit from sales was not enough to cover the warranty expenses, and, by the end of 1950, Riedel AG went bankrupt with debts of 1.25 million Deutschmark.

Legacy

At the time of Riedel AGs bankruptcy, three prototypes of an Imme with a 150 cc parallel twin two-stroke engine had been made. Fritz Philipps, who had been a senior executive at Riedel AG, formed Zweirad-Motoren und -Getriebe GmbH (ZMG) to supply parts and perform repairs on Imme motorcycles. ZMG also set up to manufacture an Imme with a 175 cc straight-twin two-stroke engine, but made only 25 before they ended production. The Imme R100 is noted for its simple and innovative design. Its advanced features include single-sided suspension front and rear, interchangeable wheels front and rear with the option of a spare tyre, the complete

drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train) or transmission system, is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the driv ...

mounted on the

, and the swingarm tube used as the

exhaust pipe An exhaust system is used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall syste ...

. Remarking on the R100 being displayed in the Solomon R. Guggenheim Museum exhibition "

", Ultan Guilfoyle, curatorial adviser at the museum, said: "It's my favourite unknown bike. There are ideas there that are 40 years ahead of their time." An R100 is on permanent display at the Barber Vintage Motorsports Museum.

Notes

References

External links