HOW TO DETERMINE PACE.

Otago Witness, Issue 2355, 13 April 1899, Page 42

HOW TO DETERMINE PACE.

It is hardly possible to take up a cycling paper, a correspondent writes, without reading of some unlucky rider, who, despite his pitiful protests that he was only going at • eight miles an hour has'been fined for scorching on the evidence of the police, who put , Jus pace at anything between 16 and 24 miles in the same time. Yet in private these same tnoderate riders boast of 15 miles in 45min, $nd recount with glee how they coasted down » hill at a mile in two ,minutes *t the very i least. i " What I propose to do is to explain a method by which pace may be measured—not with the accuracy required to establish a " record," but with sufficient precision for practical ends. Given a knowledge of the gear of the machine we are using, a watch with » second hand on the handle-bar, and enough handiness with- figures to divide by nine and by 10, and the problem is very easy indeed. Take the number of inches at which your bicycle is geared, then out off one-ninth, and count how many pushes of the pedals you give with both feet in the number of seconds equal to the remainder, and that number of cycle Bteps gives very nearly the number of miles you are covering in the hour. Thus, if your gear bo 65in, that is, if each revolution of the crank-axle causes your wheel of 28in or 26in to pass over the same amount of ground as would be traversed by a wheel •with a diameter of 63in in one revolution, by taking off one-ninth, or 7in, you have 56in, and counting the pedal-strokes made by both feet in 56sec, and dividing the number by 10, you get approximately your pace in miles, pnd any remainder gives tenths of a mile. • It works out thus: The circumference of s wheel may be taken as 31-7 of the diameter. 6o the circumference of a wheel with a diameter of 63in is 198 in, or 16ft 6in. But 10 pushes of the pedals, or-five revolutions of the /wheel in 56sec, amount in an hour to 321 3-7 revolutions; and a mile is passed- over in 320 revolutions. This leaves an overplus of 7yds .•Bft, and nearly 7in, However, there ia no *yre, be it ever so well inflated, but yields" A little beneath the weight of machine and 'rider, and so reduces somewhat the practical j Hjircumference of the wheel, and if the depression is only the sixteenth part of an inch, it is enough to use up the 7yds 2ft and 7in '.that have apparently spoiled the accuracy of jour calculations. ' The gear of 63in has been chosen because ft is one of the commonest for roadsters, and also works out very easily, but if any othor near be taken the result will be the same. Thus, with a gear of s+in, we must count our steps for 48seo, and divide by 10 to arrive at our rate in miles; with a gear of 58£ in we I Count for S2sec, and so on. For a gear bej *ween the numbers that divide evenly by 9 4jr, w* ought strictly to add or subtract ithe second from the time corresponding to ; the nearest gear that does co divide; for every 1 l-Bin our gear is above or below it. A simple rule is to take away from the number of seoonds corresponding to the nearest gear above our own which divides out by 9 or 44, one second for every inch our gear fallc below it. The amount of error will not prove yery serious. A gear of 68in may be taken as an example hi one where the variation from exactness is at its highest. The gear of 72in is the nearest abote 68 that gives an -even number when one-ninth is taken away; bo aa 68m is 4 leu than 72, and the seconds corresponding to 72 gear amount to 64-, we take off iotfr and count our steps for exactly one minute. As 'this is the exact time for a gear 01 67jtin, according to our method, we ought to count for 69 5-9 sec only. The loss of this four-ninths bf a second would cause us to under-estimate bur rate by about a furlong if going at 17 %oiles.an hour. The following is a table showing the number of seconds for which our steps should be toounted when riding a few of the commoner gears, so that by dividing the number thus counted we may arrive at our pace per hour in miles and tenths of miles: — Gear. Sees. Gear. Sees. Gear. Sees. 54 48 13 58 &.ii t£ Mi 50 65i 58 72 «4 58} 52 67* 60 10S 96 Where the gear is below 67£ in, it will be found most convenient to begin counting •when it wants just the number of seconds we need to the completion of the minute. Thus, with a gear of 63, we start numbering our steps as soon as the hand of the watch is 4sec past the minute and stop counting when it next-reaches the exact minute. With a ibigher gear it is best to begin our counting a* many seconds before the minute, as the whole number of seconds we require exceeds 60. If, for instance, having a gear of 72in we want to count for 64sec, we had better fctart off 4sec before the minute rather than try to go on just 4sec after the next It is easier to, begin at an odd number than to end at one.—H., in the Hub.