November 23. 1899] 



NATURE 



89 



limit of the quadriceps cruris at the point where soreness is 

 usually felt, i.e. just above the knee, appears to be that corre- 

 sponding to an F of 120 lbs., so that in this case with a multiple 

 of 5, whether the arrangement be 6A-inch cranks, 65 gear, or 9^- 

 inch cranks, 95 gear, a gradient of i in 10 can be ridden, and it is 

 probable that this limit can be reached for three or four minutes 

 without causing the muscular soreness. This of course varies 

 greatly with the physical condition of the rider, but it is prob- 

 able that this elastic limit is a function of the cross section of 

 the muscle, and that the above value may be taken as an 

 average one for men of average physique ; with women it is 

 probably somewhat less. It appears certain that the value of 

 the elastic limit is a most important determining factor in 

 designing a cycle to enable a. rider to develop his physical 

 powers when cycle riding in the most efficient manner. Once 

 we determine it we can fix on the multiple M, and then, as we 

 desire to keep down the nerve waste by reducing the crank 

 revolutions for a given road speed, we can only do this, as M is 

 a fixed quantity, by increasing the crank length. To what extent 

 can this be done to give the best possible efficiency ? The rider's 

 thigh bones and the muscles that work them up and down may 

 be looked upon as levers working on the hip joint as a fixed 

 point, the outer ends being connected to the pedal by the shank 

 bones, ankle joint and foot acting as a rather complicated 

 connecting rod. The effective length of the thigh bone 

 of riders varies between 15 inches for short men 

 and 23 inches for tall men. The length 

 of the standard 6J-inch cranks is there- 

 fore 43 per cent, of the length of the thigh 

 bone on short riders, but only 28 per cent, 

 of its length in tall men. In the ca.se of 

 the writers it is about 35 per cent. It 

 was necessary to determine this proportion 

 of the crank length to the thigh-bone 

 length. 



Our experiments, extending over three 

 years, show that although we have gra- 3 

 dually increased the crank length from 5 

 6i inches to 9^ inches, in other words, S 

 from 35 per cent, up to 53 per cent, of the | 

 effective length of the thigh bone, we J 

 have not yet passed the point of greatest i 

 efficiency. Oui proposals have of course ? 

 been severely criticised, mainly by those 5 

 who have not tried the system, and the \ 

 following objections have been urged S 

 against increased crank length. 



(i) Causing loss of power when hill 

 climbing, or when riding against the 

 wind, in fact at any time when the F 

 required is considerable, and that this 

 loss of power is caused by the excessive 

 bending of the knee joint, which in its 

 turn causes knee soreness. 



(2) Militates against proper ankle *^"^- '-Curv. 

 action. 



(3) Causing saddle soreness, bad steering, and other troubles. 



(4) Causing extra strains on the parts and frame of the cycle. 

 Dealing with these questions in the above order, we have 



shown that the main object of increasing the crank length is to 

 reduce the number of revolutions at a given road speed without 

 increasing the value of F, and as it is practically certain that the 

 knee soreness complained of entirely depends on this value of F 

 not being exceeded, the only other way in which knee soreness 

 could be produced is by excessive knee flexure. There are two 

 ways in which this question of knee flexure may be considered. 

 It has been said that when the knee is bent beyond a certain 

 angle the muscles act at a disadvantage, and again that the extra 

 flexure of the joints is the cau.se of the soreness which riders 

 complain of, and that a rider having an 18-inch thigh bone can 

 actually exert a greater pedal force at the half-stroke of 6i-inch 

 cranks with its corresponding knee angle, than he can with 

 9 inch cranks and the correspondingly increased angle. We 

 have, however, settled this question by careful experiments made 

 in a testing machine, and we have shown that the knee angle at 

 which the maximum pushing strain can be exerted is that which 

 corresponds to a crank length of 18^ inches ; in other words, that 

 the maximum force of the leg is obtained with a knee flexure far 

 in excess of that required for any possible crank length that could 

 be used on a cycle, so that this question of loss of power from 



KG. 1569, VOL. 61] 



excessive knee flexure is completely disposed of. Fig. i shows 

 these results plotted on a curve. 



Table IV. 



What writers mistake for knee soreness caused by excessive 

 flexure is really due to the following cause. Any muscle which 

 is constantly used throughout only a part of its stroke becomes 

 developed and hardened into a condition which Sandow calls 

 " a muscle-bound condition." It becomes shorter as it is never 

 properly stretched out, the tendons which secure it also become 

 shortened, r.nd if this condition is not speedily remedied it 



75"3o' W'36' 83°"' 86" 87'44' 9J'46' 97*3j' loi-jj' 



ANCLE AT THE KNEE JOINT. 



showing relation between knee angle and maximum thrust on pedal. 



becomes permanent. In the hard riding short crank cyclist, 

 ; this applies to the quadriceps cruris, it being only called upon 

 to work through a part of its stroke. When suchacyclist uses long 

 cranks for the first time, he finds himself unable to properly flex 

 his knee joints on account of this shortening of the quadriceps. 

 The effort of stretching the muscle out to its full stroke causes 

 the knee soreness complained of There can be no question, 

 however, that long crank riders benefit greatly by the extra 

 knee flexure, compelled by the long cranks, and that this greatly 

 increases their bodily activity and enables them to excel in 

 exercises, such as running, walking, hill climbing and jumping, 

 all of which require flexibility of the knee joint. Sandow points 

 out that the best way to prevent the muscle-bound condition 

 is to work the muscles in pairs throughout their full stroke ; 

 consequently, if we desire to develop the quadriceps cruris in 

 a perfect manner to the full length of its stroke, we must also 

 develop the muscles which form the pair to it on the underside 

 of the thigh, i.e. the biceps cruris. It occurred to us, therefore, 

 at an early period, that we ought to train these muscles to do 

 their share of the work of propelling the cycle, hence arose 

 what we call the pull stroke. Cyclists who use toe clips, or 

 those who notch the soles of their cycling shoes, so as to get a 

 better grip of their pedals, can use this pull stroke to a small 

 extent ; that is to say, they can claw or pull the pedal round 



