OSSA has developed a trial bike, based on a new, highly innovative concept. Ossa has basically worked on redistributing the various parts of the bike logically in terms of the weight distribution and other conditioning factors such as locating the filter box in a very high, easily-accessible position.

Parts such as the fuel tank, air filter box and radiator have been positioned with the needs of a trial bike in mind. This has been done rationally, with common sense and a clear objective: to make the new OSSA TR 280i a benchmark for this specialty, just as the first MAR – Mike Andrews Replica – was in 1972.

"Having the air filter at the bottom of a trial bike with the fuel tank high up or located next to the exhaust are concepts that do not make sense from our point of view," says Xiu, the project manager. So OSSA’s engineers approached the design of the new OSSA TR 280i by putting the various parts of a trial motorcycle on the table and taking a blank sheet to design and redistribute them based on their needs..

The new two-stroke engine is very compact with a single piece crankcase. The gear change extends out of the right hand side and the crankshaft is opposite it on the left. Since the housing acts as the chassis, as it is the toughest part of the lot, it has been possible to make a compact block. This simplifies the possibility of access to gear ratios.

Another important aspect is that it is cheaper to maintain since it is really straightforward to work on the engine. It can be considered a conventional engine in terms of geometry or thermodynamics, but Ossa have managed to design a highly compact unit. It is one of the smallest engines around.

The 3-litre fuel tank has been positioned where the radiator has traditionally gone on trial bikes in order to improve the weight distribution. The OSSA Factory team thinks that the lighter a trial bike is the greater the need for the centre of gravity to be shifted forward.

Placing the radiator behind the fuel tank and filter box prevents the radiator from getting covered in mud, which happens so often in trials with the resulting problems with the engine not being able to run at the right temperature. A stationary motorcycle needs to be able to dissipate the heat from the engine and have a fan fitted on it like on the TR 280i. So although a motorbike used in a different specialty would need fresh air channeling, a trial bike does not.

Since the fuel tank protects the radiator, the new TR 280i can run at a constant temperature without being held back by a dirty radiator. Also, by inverting the cylinder OSSA have been able to fit the inlet practically vertically behind the fuel tank, so the air comes in through the filter at one of the highest points on the bike. This makes the filter better isolated and it is much simpler to get at the filter itself through a cap. Some parts of the injection system are fitted inside underneath the cap. There the parts are not affected by either the engine itself or humidity.

When Ossa distributed the motorbike’s parts they paid close attention to the temperature at which they would each operate. Since the cylinder is tilted back and the exhaust points backwards, the exhaust can start from the rear mono-shock, which has a larger volume than on a conventional bike.

The steering pipe, treated aluminum tank, footrests and articulated rod support are also made of cast aluminum. The rest is made of chrome molybdenum steel with a very simple TIG-welded structure.

The suspension has been developed in conjunction with Öhlins (rear) and Marzocchi (front). The rear suspension has an innovative system with an articulated linkage that is well protected and integrated, and is directly joined to the cast part of the chassis. The Öhlins TTX system has been adapted to trial bikes. This is a system in which the piston valves and hydraulic adjustments have been put on the outside. This technology has already been used in motocross and has many advantages for adjustments in terms of simplicity and accessibility.

The front suspension is an upside-down Marzocchi fork, a kind of suspension that has not been used on trial bikes for years. However, unlike other experiences of adapting motocross or enduro suspension, an upside-down fork with aluminum bars has been designed for the TR 280i in close collaboration with Marzocchi, which is exclusive to trial bikes.