HIKE-INCH CRANKS.

Otago Witness, Issue 2323, 8 September 1898, Page 42

HIKE-INCH CRANKS.

ARE THEY HELPFUL? By W. F. Ball. The theory is again advanced in favour of & high sjear used in conjunction with long cranks, and what must at leasb be regarded as a good prima facie case has been made out in support of it. Put briefly, this theory is that the pressure applied by the rider's foot to the pedal will be exactly the same with a 90 gear and a 9in crank as with a 60 gear and a'6in crank. Then there is the advantage of the slower pedalling when the high gear is used, and the disadvantage of the enlarged circle or orbit which the foot has to traverse. It is assumed that these two balance one another, the loss in the one direction being equal to the gain in the other. Then it is claimed that the net advantage results because ihe long cranks admit of, or rather necessitate, the pedal thrust being given .when the leg is well bent. Many people "would be disposed to regard this as a very problematical £am but for the moment we will assume that there may be something in it. If there is, a clear mechanical advantage would appear to be secured by the use of a long crank such as 9in, and .a high gear to correspond. Now this theoiy is not like the Simpson chain or the Boudard gear, to be discarded as fallacious by every unbiassed engineor after five minutes' thought. It is a good idea ,well thought out, and is advanced and supported by gentlemen who have reputations as mechanical experts to lose. I must admit that I am not convinced by it, but for all that I feel perhaps more interested in the theory than in any score of the hare-brained ideas which have done duty for novelties during the boom. Cycling and cycle "eogineering are not ■wholly mechanical arts, as, for instance, the building and driving of a locomotive engine might be said to be. In cycling the factor of the human body — its powers and its adaptability — enters very largely into the calculations, and for this reason mere mechanical knowledge is quite inadequate in itself, and •unless it is allied to a thoroughly practical experience of cycling, it may give us results which are harmful and misleading. It must be said that the 9in-crank people are practical — at any rate ud to a certain pomt — but I

, cannot think that their experience of the ' wheel has been a very wide one. { The whole que&tion is one more of adapt- ' ability than of mechanics. The engineer may work out to a nicety what the theoretically j best leg position is. He may give us the . exact angle between the upper leg and the lower, and indicate the precise degree of , deflection from the horizontal at which the , thigh is capable of putting in its best push. 1 Such information is, of course, useful, but j I urge that we must not be guided by it alone. One point in connection with crank length, and the position and action generally, is | often overlooked, and to which I should like to refer. It is this, that successful cycle riding does not consist in putting in those huge thrusts for which the engineer theorist would have us prepared. It is, of course, sometimes , useful, and indeed necessary, to push hard at the pedals, but 99 strokes out of every 100 are easy, light strokes, and it is really more important to secure a position and a crank long th which v. ill pdmifc of making those 99 strokes with ths £icnt<\st bodily ease and convenience than it is lo be well placed for tho°e herculean efforts which are but rarely needed. ! Position and crank len^tn must, of course, be a compromise to a great extent in exactly the same way that a medium gear is a compromise ; and althoiigh a position from which power can be readily applied is a point, a position which will admit of e"isy, comfortable, light pedalling is a ereater one. Everything appears to me to turn on the suitability of crank length from the stricil"- physical point of view. It is obvious that a 12in crank would involve a leg a.ction so exaggerated that, even at a very low rate of pedalling, the lower limbs would rapidly tire, while their excessive movement would probably cramp the rider's breathing, and set up a good deal of unsteadiness in the trunk, which would be alike uncomfortable to ths cyclist ana a waste of bis energy. A 2in or 6m crank, on the other hand, would provide a working orbit for the foot so snip 11 as to be quite out of proportion with the length and size of the human leg. Evidently some | length betwesn these two extremes is called i icr. _ j In the early " ordinary ' days, some racing \ machines had cranks as short os When J the " G. 0.0." had reached its prime, s^in was perhaps the most usual length, though on ' roadster machines spn and even 6in were not j ' unusual. To-day we have adopted 6£in as j standard, though 64:111 is often called for, and ( faiin and 7in are by no means rare. Some variation must, of course, be allowed to suit individuals of different heights, bu J j I have never yet seen a crank over 7in which appeared to benefit the man who used it, and 1 am in- , clined to think that above 7m or thereabouts ' ' the gain in leverage is more than cotmter- ' acted by a reduction in the rider's comfort and convenience. One aspect of the crank-length question must not be overlooked. For lioht easy pedalling it is best to set the front of the saddle a little behind the crank-axle. Now, if we increase the crank length 3in, it is obvi- ] ous that the saddle must be brought forward nearly if not 'quite as much for if this be , ■ not done the pedal when it is half way on \ ' the down stroke will be too far ahead, and out of convenient reach. Some loss in comfort is here apparent ; but, so far as my ideas ! go, the action of the man riding a 9in crank , cannot fail to be ungainly and uncomfortable in some degree. ; j It is true that few people have tried 9in 1 cranks,, and, therefore, we have before us , very inadequate evidence of what they are worth, but many people have tried 7in cranks, j and some 7^in. I know personally those who ( have been at some pains to test these lengths, j and who have made extended trials of them. \ j With one exception all have come back to ■ ! 6£in, and the almost universal use of this | , length to-day is, to my mind, very good proof j i that the 7^in crank has not revealed any ad- , ' vantage either u> the racing man or to the j ' tourist, and I think it is a fair deduction to ■ , say that if 7£in has not found favour, and ! . has not shown itself to be of any appreciable ; ' advantage to the rider, the 9in crank is, if any- i i thing, less likely to succeed. j