FAST MOTOR CYCLING.

Otago Witness, Issue 3467, 24 August 1920, Page 42

FAST MOTOR CYCLING.

T. Do la Hay won the senior l division of the Tourist Trophy Motor Cycle Road Race, the Bluo Riband road contest of England. The contest was a particularly keen one. The course is a mountainous circuit in the Isle of Man, six laps having to- be negotiated, making a total of 226 i miles. Thero were 27 starters, the cubic capacity of tho engines being limited to 500 cubic centimetres, equivalent to 3i horse-power.

The weathar was fine and the tricky course in good order, .although a bit greasy in places owing to rain on the previous day. The contestants started at minute intervals. The first circuit {37£ miles) was negotiated by G. Dance (Sunbeam) in 41min 28sec, the same rider, doing the second lap in 40min 43seo (55mfles per hour), remarkable travelling for a course that was full of dangerous "hairpin" corners. A broken valve stopped the great ride of Dance's, the pace being too hot to last.

After four laps (150 miles) had been completed D. M. Brown (Norton) was in the lead, with De la Hay (Sunbeam) and R-

Brown (Sunbeam) following. There wers* only 16 riders now left, mishaps, falls, ancl machine troubles having reduced the field* The conclusion of the fifth lap miles) saw De la Hay in front, and he maintained his lead to the finish, winning by foun minutes in the record time for the course c-B 4hr 22min 25seo. D. M. Brown was eecond> in 4hr 26min 13sec, and R. Brown third in 4hr 32min 27seo.

The winner had no trouble with his machine, his fastest lap being the last—at an average speed of 55 .miles per hour. The first and second men used J>unlop

so that equal braking force is applied to both back wheels at the same moment. The test 3 were made with a car on which

an independent brake to each rear wheel was fitted, and no matter what the condition of the road surface there was no tendency to skid when either of the wheels was locked with the brake, nor was there any loss in brake efficiency. In fact, it ia claimed that the now system was more effective ' than that now fitted as standard. The car used was a four-seater, with empty rear seats, Avhilo tho tyres on the rear wheels had identical treads. When proceeding at 45 m.p.h. the off-side wheel was locked, and the car pulled up rapidly, travelling in a straight line, while there was

the same result when the near-side wheel was locked. The next test was the application of both brakes simultaneously, the result being that the passenger was unseated, so suddenly did the car come to a standstill.

The driver then tried a rather nerveracking experiment while travelling at maximum speed, for as he applied the brakes ho turned the steering first one way then another, demonstrating that the car could be driven in any direction desired with one of the wheels looked. This wheel left a snakey track from ono side of the road to the other, following the steering wheels precisely, while there was no trace of skidding, yet one would have expected the car to make a rightabout turn. In all of these tests the clutch was withdrawn, hut a further test was made with the clutch left in. This, with the ordinary differential gear, had the effect of increasing the gear of the wheel that was driving; again the results were the same; it seemed impossible to make the- car skid, even_ with ono wheel braked and the other driving. An almost parallel case is that of the sidecar, where the brake operates on tho singlo driving wheel, yet the motor cycle and sidecar combination does not skid; it is of all motor vehicles the most immune in that respect.

Since the experiments wore made and the results noted, several motor experts have been considering as to whether or not we have accepted and perpetuated a practice (which dates back from early motoring days) without scientific investigation. Is there any reason why the car should skid because only one wheel is locked? Further-, if the brakes are accurately compensated—a very fine point to decide—do thev remain so for any length of time? One of the engineers gave his opinion of the matter in these words: —"My experience is that they do not; and, even if their action is simultaneous, would not the compensating device or action be negatived bv variations in the road surface with which the off-side and the near-side wheels are in contact, and by the difrerence > in the treads of tvres?" That is tho point in a nutshell. Concluding he says:—"The more. T think about the idea the more convinced I feel that we are'following a fallacy."