HOW TO CALCULATE SPEED AND DISTANCES.
By W. B. Eyre (Hou. Sec. Pioneer 8.C.). As I have no doubt cyclists generally would be glad to know a simplq means whereby they can tell not only how fast they are riding, but what distance they, have gone, I have prepared a series of tables iu'tlie hype that the information may be of eoino u*e to my wheeling friends. ' ~ Table 1 shows how a rider cau tell how fast he is going, or how to regulate his pace so that he may ride exactly at the rate of the number of miles an hour required. For iustauce, say he rides a 55in machine. ' He starts going, takes out his watch, and counts the number of revolutions, of his crank (which, at the end of ,a minute, amount to 43). He will therefore be going at the rate of seven miles an hour exactly. If he wants to go 10 miles an hour he must turn the crank 61 times a minute, and keep going at that speed. Of course the watch need not bo kept m the hand more than a minute or so, because when a rider has properly started it is an easy matter to keep up a set pace.' Table 2is a more important one, masmucli as it will enable anyone to measureanydistance accurately, as in the; other table, without a pedometer. For instance, a trainer wants to measure out a mile for racing purposes ; the machine being ridden is a safety, geared to 54m (a 54in " ordinary " is, of course the, same). You start off and carefully count the revolutions of the crank (that is of one pedal), and when these amount to 373, then you have gone exactly a mile. On a 56in, 360 revolutions make a mile— to be exact 1759 yd Ift 3in, or lft 9in short of a mile. This, I think will be admitted, is near enough. I have gone into the figures carefully, and will guarantee accuracy. The calculations are based on the work of solid-tyred machines, but for Dunlop pneuma* tics it will be necessary for a rider to make an allowance equal to one yard in every 30, as the tyre being of a yielding nature, the circumference lessens when the rider is on the machine — that is to say on a 56ip machine, with Dunlop pneumatic tyres, it would take 360 plus l-30th,
equals 12, or, 372" revolutions of crank, to go a mile, and so on. iOn Clincher or Boothroyd pneumatics the difference between them and solid tyres is hardly" .worth , mentioning—so far as circumference is concerned. I append the tables —
Explanation.—Supposing you are riding a safety geared to 56in, or an ordinary, 56in in diameter, then 90 revolutions of the crank will take you quarter mile; 180,' half mile; 270, threequarter mile; and 360, one mile. I was going to say exactly a mile, but the distance is 1759 yds lft 3in, or lft 9in short of a mile.
H (t> IS Pj S3 (S c en- qi vi H £- go CD M M- <- ■ n &§« I a o 5? I it o SeSSS?g?BBJSSBB&& O) gSSSfe&SkS&S w fcfegssfefefessas oo ggJSSSSSSSSS r° - gss^a^^a^sg 323^33882828 S3?2SSS^BgBSSe gsgggggSSSSS^ gssss^s&ssas o' 0) a O to 8 5s5 s en r as p M * 'l 1 p ggggSSSSSSJ <3i j_l h ji_i>_iH-'t-l>-'h-< SooOOOHHHHtS - 35 CO O N *«• Ot -<J © IS iiS -3 l£l w«>.a>ot>oto^*^cptofe 8 No. 2. Distances. k ° >> -I* 09 all *8* it 3j Inches, 50 51 52 53 54 55 56 57 53 5!) 60 101 99 97 95 93 92 90 89 87 86 . 84 202 198 194 , 191 187 183 180 177 174 171 168 303 297 291 285 280275 270 265 261 256 252 403 395 388 381 373 366 360 354 348 342 336
HOW TO CALCULATE SPEED AND DISTANCES.
Otago Witness, Issue 1994, 12 May 1892, Page 30
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