1988 Yamaha press information TDR development targets
A NEW MOTORCYCLING DIMENSION
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| Upswept dual mufflers and a on-off type seat give the bike a unique look from behind. |
Introduction
When Yamaha engineers' started the TDR development project in 1985, they were faced with the task of creating a new-concept motorcycle which would break away from the racer-replica trend of the 1980's and, most importantly, reemphasize the "FUN" aspect of motorcycling.
Working on the premise that the TDR should be capable of being ridden on all types of road surfaces in a practical and enjoyable way, their target became clear. They had to build a motorcycle whose performance created a new dimension in terms of acceleration, manoeuvrability, handling, stability and braking, and which also enabled the rider to extract the maximum in driving enjoyment from everyday use!
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| Communication strategy in 1988: TDR 250 comparing to a Lotus Super Seven. Both vehicles are known for their extreme agile handling, build for narrow roads. |
Beginning Development
To build such a motorcycle whose performance envelope should encompass the various conditions as envisaged by TDR was not going to be an easy matter for the simple reason that TDR was to be the first of its kind, indeed a new-concept!
The development team considered how to approach the
project and decided, that as this motorcycle had to combine road and
off-road features in a new way, they should start by reassessing the
positive and negative aspects of road and off-road bikes. To do this, they
chose a novel method by taking a TZR25O, RD25OR, DT200R and Serow (XT)225
to Hokkaido, Japan's northernmost island. They considered Hokkaido to be a
perfect testing location by virtue of its European like climate and
variety of roads, highways, secondary mountain routes, green lanes and
off-road areas.
They rode the TZR25O on green lanes to see how it
reacted to such conditions, and the Serow 225 on a highway for many hours
to see how the riders reacted. Naturally riding in such circumstances
meant that they experienced discomfort to a greater or lesser degree.
Individual experiences were discussed, the main theme being how to convert
discomfort into comfort in order to achieve an outstanding new- concept
dual-purpose motorcycle. Finally, a consensus
was reached and TDR's technical concept was fixed, it was to be engineered
to be almost the equal of TZR25O in terms of driving capability, whilst
also being a good match for DT or XT models in its off-road
manoeuvrability. In achieving this, the engineers considered TDR would be
the "ULTIMATE DUAL".
THE DEVELOPMENT PROCESS
High-speed chassis
stability
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| In France: TDR 250 cup proved the capability of the bike on different terrain. The rules were similar to today's supermotard races. |
In beginning chassis development, the engineers had
a choice; either start with a conventional road or off-road chassis, and
develop TDR from one or the other.
Having decided to give considerable
street bias to TDR, they chose, not surprisingly to start with a road
chassis because an important priority was high speed stability. Off-road
handling characteristics would then have to be built in as much as
possible within this chassis base.
Frame design
In considering the actual frame design, a compromise
had to be reached between the high lateral rigidity of a road frame and
the high longitudinal rigidity of an off-road frame. In TDR's case the
frame rigidity of an off-road bike was chosen whilst the design followed
that of a conventional road frame. This was in the engineers' opinion the
ideal compromise for both high-speed stability and excellent off-road
manoeuvrability.
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| TDR-cup: off-road riding style is favoured in tight corners |
So a conventional double-cradle tubular steel frame
was designed and built and actually bore a dose resemblance to that of the
first RD25OLC. However testing showed that no existing design standard
could be applied to TDR's frame rigidity as, after all, it was a
new-concept. And, mid-way through development, testing showed that the
frame's tube diameter had to be substantially increased.
Also, special
care was taken when assigning design priority to various chassis
components which in themselves made a unique design approach necessary
requiring less regard for aerodynamics and motocross
manoeuvrability.