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Union (It has done and is doing)

It has done, and is doing, excellent work in spreading among surveyors the true principles of road construction. 50. The Touring Club de France (Avenue de la Grande Armée, Paris; subscription, 5 francs; 6 francs for residents abroad). This institution, which is admirably managed, combines the functions of the British C.T.C. and Roads Improvement Association. It is open not only to cyclists, but to all classes of tourists. It exercises great political influence (not, of course, of a party character), and has been of immense service in improving the conditions of touring in France. 51. Cycle Shows. -The Stanley Show, which is held under the auspices of the Stanley C.C., dates from 1877. At this show, which is held in November, are exhibited the standard machines of all makers of any note, as well as all the novelties intended for the coming season. IX. DETAILS OF THE MACHINE. 52. The bicycle consists of two wheels placed tandem-wise, and mounted in a frame of steel tubing, which carries the saddle and driving gear, and is hinged in front to permit of the front or steering wheel turning freely from side to side. The frame thus falls into two rigid portions-the Front Frame, which carries the steering wheel; and the Rear Frame (commonly known as the frame simply), which carries the saddle, gear, and driving wheel. In Fig. I the names of the principal parts of the machine are given and distinguished by numbers. their points of junction into hollow stampings or The Frame is made of steel tubes, inserted at castings of metal, known as "lugs," held there by brazing, and internally reinforced at these points by short pieces of tapered or serrated tube, known as liners. The tubes themselves are often butted, i.e., made thicker toward the lugs, in which case liners are not used. In either case the object is to prevent a sudden step in the thickness of metal.

In some machines (e.g., the Rudge-Whitworth) the tubes are outside the lugs. Such frames are tubes are outside the lugs. Such frames are called "flush-jointed." They are neater in appearance, are easier to clean, and have no edges to rust.

The top tube, which en ordinary machines is machines usually dropped towards the head, so horizontal, is on racing and road -racing as to save the necessity of a big drop in the handle-bars. The names of the component tubes are given under Fig. I. 53. Varieties of Frame. -The most rigid form in which tubes can be arranged is the triangle, and frames in which this principle is carried out are said to be triangulated. The back half of the triangulated, but the front half is not, as it conrear frame of the ordinary pattern (Fig. I) is the ordinary pattern (Fig. 1) is sists of a quadrilateral of tubes. In the following varieties of frame the principle of triangulation is more fully carried out: I. The Raleigh cross frame. For the top tube are substituted two tubes running respectively from the seat lug to the bottom of the head D2 and from the crank bracket to the top of the head, and crossing one another in an X-shaped lug. It will be noticed that by this arrangement the whole of the frame is triangulated and perfect rigidity secured (see Fig. 2a). 2. The Centaur Cross frame. An additional pair of tubes run from the top of the head to the [CYCLING 4. Enfield. A tube runs from the bottom of the head to a point in the diagonal about four inches above the crank bracket, whence a second tube runs to the bridge of the chain stays.

The French Clément Company make the same frame.

The Elswick is practically similar, and is illustrated in Fig. 26. 4 34 5 33. 35 3 2 6 38 37 36 27 32 23 9 29 26 22 31 63 28 19 20 13- 12,8 21 24 14. 10 25 39 30 57 52 15 61 16 41 45 60. 46. 53 62 40 44 51 4-2 4-3 47/ 18 17 59 55 54 48 49 50 58 56 JENKINSON I. Handle.

N.B.-The brake-work here shown is not of the most usual type. The latter is shown in Figs. 25 and 26. 2. Brake lever (inverted). 3. Bolt of brake lever. 4. Guide of front brake rod. 5. Lamp bracket. 6. Head clip. 7. Bolt of do. 8. Stirrup of front brake. 9. Front brake rod. 10. Brake shoe and block. 11. Brake fork clip. 12. Fork crown. 13. Bolt for mudguard. 14. Clip for back brake cable. 15 Cable for back brake. 16. Front hub..

PARTS OF THE BICYCLE. 17. Clip for front mudguard stay. 18. Front mudguard stay. 19. Front tyre. 20. Front rim. 21. Spoke nipple. 22. Adjusting-clip for front brake. 23. Top tube. 24. Diagonal. 25. Bottom tube. 26. Head tube. 27. Transfer. 28. 29. 30. } Pump-clips. 31. Back stay bridge with clip for mudguard. diagonal, and thence to the back wheel. The chain stays are duplicated (see Fig. 2b). 3. Chater-Lea (and others).

The top tube is duplicated by a second tube from the bottom of the head to the diagonal, from which an additional pair of tubes may run to the back hub. The triangulation of this frame is not complete (see Fig. 2c). 32. Seat lug with bolt and nut. 33. Saddle spring. 34. Adjusting bolt of saddle. 35. Oil can (inside saddle pillar). 36. Saddle pillar (L pin). 37. Bolt and nut for 38. 38. Saddle clip. 39. Back (or seat) stay. 40. Stays of back mudguard. 41. Back fork end. 42. Clip of mudguard. 43. Back wheel spindle and nut. 44. Chain stays. 45. Chain. 46. Back brake stay-clip. 47. Brake shoe and block. 48. Stirrup of back brake. 49. Stirrup rod of do. 50. Bell-crank for do. 51. 52. } Cranks. 53. Cotter. 54. Frame of pedal. 55. Barrel of pedal. 56. Spindle of pedal. 57. Dust-cap of pedal. 58. Crank-axle. 59. Chain-stay bridge. 60. Chain adjusters. 61. Front fork. 62. Chain wheel. 63. Oil-hole for head. 5. Premier. An additional tube runs from the seat lug to the bottom of the head Such frames as those described under 1, 2, and 5 above are perfectly rigid, and every ounce of work put into them is used to advantage . Their extreme rigidity, however, somewhat accentuates the vibration felt from the road; moreover , in the event of an obstacle being encountered, the THE TATE LIBRARY, BRIXTORW. moved downward sufficiently to give clearance for them, and this is done by carrying it (in either a straight or a curved form) from the top of the head to a point above the crank bracket, so that we get a frame like that shown in CYCLING] whole force of the collision is, in virtue of the rigidity of the rear frame, concentrated on the front forks and the bottom of the head-which are the weak parts of the bicycle. The ordinary frame gives a little in collision, and relieves the strain on the front frame. It is only fair to add that we have not heard of accidents arising from this cause. The X frame enables the rider to dismount easily through the frame, in the same way as from a lady's bicycle, and it is thus very suitable for use with trailers. (See para. 32.) Fig. 4a.

All these frames are specially suited for tall riders, as ordinary frames with a diagonal exceeding 27 in. are apt to be whippy. It will be seen that while the crank bracket is stayed in the same way as in a man's machine, the rigidity of the front part of the frame is entirely done away with. The diagonal, upper backbone, and head tube form a U, open at the top, which, when the front wheel is checked by any obstacle, tends to close up, thus putting a shearing strain on the junctions of the two backa. The Raleigh Cross Frame. b. The Centaur Cross Frame.

FIG. 4a. c. Frame with duplicated top tube. 5. The Dursley-Pedersen has both front and rear frames triangulated. It is not, however, every rider who appreciates the rocking of the saddle, and on slippery or rough ground many prefer an ordinary rigid saddle. The head, moreover, with its plain bearing, is decidedly primitive, and the makers have sacrificed too much to enable it to be taken readily to pieces. It is, however, a perfectly sound machine, and the drive is rigid, while its weight (about 26 lb. fully equipped) is much below the average. 54. The Frame of Women's Bicycles. As the great majority of the weaker sex continue to ride in skirts, the upper backbone has to be FIG. 46. Specially stayed frame for woman's bicycle. Elswick. bones with the diagonal. In the Elswick the bottom tube is duplicated, and the two tubes are crossed. This is an improvement, and better still is the Elswick frame shown in Fig. 4b., in which, in additon to the duplication of the bottom tube, yet another tube runs from the bottom of the head, intersects the diagonal and ends at the bridge of the chain stays. 55. Height of Frame is measured from the top of the seat lug to the centre of the crank axle. The seat pillar should never project more than two inches from the seat lug: nothing puts a more unfair strain on a machine than to subject it to the leverage of the weight of the rider at the end of a long stretch of saddle pillar. Hence a tall rider may require a frame of from twenty seven to as much as thirty inches.

Frames are made in different sizes, each two inches above the other. Some makers build them in even numbers of inches, others in odd numbers.

Standard sizes are, as a rule, from 21-27 or 22-26, in the case of men's, and 21-25 or 20-24 in the case of women's. Juvenile machines are 18-20 or 17-21. 56. Weight of Machine is best considered in connection with its most important constituent, the frame. It must be remembered that a cycle must be built strong enough not merely to sustain the weight of the rider, but also to withstand the strain of driving. A machine may answer the former end, yet may be so light (or have its weight so badly distributed) that the frame is twisted out of line at each stroke of the pedals; not only is much force wasted through this undue elasticity, but the chain wheels may be set out of line and much friction of the chain result.

Such a machine may run tolerably when the work is easy, but uphill, against the wind, or at high speed, it will be much inferior to a heavier, but more rigid, machine.

To test the rigidity of the frame in this respect, set the machine up, hold it firmly, and press with the foot on the downward pedal: the machine will in any case give, but a little experience and comparison with a cycle known to be rigid will soon show the amount of spring legitimately to be expected. An unduly whippy machine should be let alone. A heavy rider will require a heavier machine than a lightweight, especially if he be also tall and require a high frame; the greater length of the tubes admits of more give than in a small frame, and the weight should be more than proportionately increased.

Speaking generally, we should say that an experienced rider of about II st., who understands pedalling, may on ordinary roads ride a machine weighing, with road racing tyres and saddle, and with two brakes, but without mudguards, gearcase, &c., 24 lb.; light roadster tyres will add about 1 lb., a roadster saddle about 1 lb., a gear case 2 lb., and light mudguards over 2 lb. more; a machine weighing with these accessories 33 lb. is heavy enough for anyone up to about 14 st.; 36 lb. ought to suffice even a very heavy weight. 57. Tread. The tread is the distance apart of the feet in pedalling; it should, strictly speaking, be measured from the inside plate of the pedal, where it touches the side of the foot; in practice, however, it is measured between the outside of the crank bosses, i.e., it is the length of the axle. The following may be taken as typical treads :- Racer, 4 in.; light roadster, 4 light roadster with gear case clearance, 41; full roadster, 53 9 58. Clearance of Wheel. It is important that there should be adequate clearance between the tyre and chain-stays or gear case, otherwise mud will lodge on the latter and hinder the running.

It should just be possible to get the finger in between. This should be borne in mind in specifying the diameter of tyres. Few machines will take comfortably a tyre larger than 1 in. 59. The Head. The head of a bicycle is the hinge where the upright tube of the front portion of the frame, which rigidly connects the handlebar with the front wheel, swings on ball bearings inside the socket formed by the front tube of the rear frame. Its construction and adjustment are described under Figs. 5 and 6. 60. Steering locks are valuable, not only as security against thieves, but for preventing the head from turning when the machine is a [CYCLING leaned against a wall, turned over for tyre repair, &c. They fall into two classes: (1) friction steering locks, in which the turning of a screw clinches on to the movable part of H F D C G A AE E K L G B To put together. A is the inner steering tube (or post); round it, just where it emerges from the fork crown B, is fixed the lower half of a ball race c; the balls are placed in position, and the complementary upper half D dropped upon them; the steering socket E is slipped over A and lowered on to D; into its upper end and round A is placed the lower half F of the upper bearing; the balls are placed therein, and the clip G, in which is incorporated the upper halfbearing is dropped on to them; a milled or hexagonal ring K is then screwed over the inner steering tube and down on to the clip G so as to obviate any vertical play (in most machines the lamp-bracket is first slipped over the tube and gripped between K and G; the variety shown above (H) is secured to G by a screw); the lower end of the handlebar M is passed through K and G well into the steering tube A (at least an inch further than shown above); and, finally, the bolt at L is screwed up, thus compressing the clip Gon to the steering post; this is itself split at its upper end, and so grips the handlebar tube; the entire arrangement is thus securely locked. Note.-In most machines the half-bearings D and F are permanently fixed into the ends of A.

To adjust the Head.Slack the bolt Land tighten or loosen K till the required adjustment is obtained. This is ascertained by grasping the handles, and pulling up and down on them, when any shake in the head will be felt (notice, however, that this is not due to the front wheel bearing). The head is correctly adjusted when it swings with perfect freedom, and there is no shake. If the head be unevenly worn a compromise must be effected, very slightly on the side of tightness. Such uneven wear is the result of neglecting the adjustment. Finally, again tighten the bolt L.

To raise or lower the Handlebars.-Slack bolt L, adjust the handlebars as desired, always leaving at least a clear inch and a half remaining in the head tube to give a safe hold. See that the handlebars, clip, and lamp-bracket (if secured in this way) are quite straight, and tighten the bolt L. the head a metal band attached to the immovable part; (2) positive steering locks, in which a catch attached to the movable part of the head engages in a slot or hole in the immovable part. We prefer the former, as the machine is not rigidly locked, and, if it is upset, the lock gives, whereas with a rigid lock some damage is likely in such case to be caused.

Steering locks with detachable key are rather a nuisance. 61. The Handlebar. -The adjustment of the CYCLING handlebar will be understood from Figs. 5 and 6 and para. 59, and their shape from Fig. 7. Considerations on the respective merits of these patterns will be found in para. 28. They are fitted at their ends with handles of felt, cork, rubber, horn, or other materials, which are usually cemented on this should be carefully done, as a oose handle may come off and cause a bad fall.

I 0100100 In the comparatively recent variety the bottom of the handlebar is split in four directions. A rod terminating at its upper end in a hexagon head is passed through a hole at the top of the handlebar and hangs down inside it. Its lower end is threaded, and screws into the upper end of a loose cone, which it carries. This cone carries a feather which engages in one of the slots of the split handle-bar. When the hexagon head at the top of the handlebar is screwed up, the cone is pulled up and expands the handlebar so as to grip the inner tube of the head. To loosen the handlebar, the hexagon head is unscrewed for a few turns, and a smart tap given it with a mallet. This drives the cone free of the handlebar, which is thus loosened. The object of the contrivance is to have the adjust ment of the handlebar independent of that of the head bearing. It is now possible to obtain handlebars in which the metal is coated with celluloid. This is a great improvement from the point of view of rust prevention. In some cases the handles simply consist of an enlargement of this celluloid covering (see Fig. 7). a b C a. Flat. b. Flat and Cow-horned. c. Upturned. d d. Dropped.

N.B. e e. Dropped with Extra Forward Extension.

These bars are covered with celluloid. 62. The Seat Lug (see in Fig. 1), which is situated at the meeting point of the top tube, the diagonal, and back stays, is compressed by a bolt, and grips the saddle pillar which slides into the diagonal of the frame; to adjust the height of the saddle, the bolt of the seat lug is slacked, the pillar raised to the desired height, and the bolt again tightened. A convenient device is for the makers to mark the seat pillar in inches and fractions. 63. The Saddle Pin or Pillar carries the saddle.

It may consist of a single upright tube sliding into To adjust the position.-Slack the end nuts on the transverse bolt; the clip, and with it the saddle, may then be shifted to any position upon the L-pin; then tighten the nuts.

To adjust the tilt.-Slack the nuts as before, when the saddle and springs may be swung bodily upon the bolt to any desired tilt; then tighten the nuts. In all cases see that the clip grips the spring wires in their centre; adjustment should not be obtained by sliding the wires along the clip.

NOTE. The above type of clip will fit either an upright or L-shaped pin. the diagonal of the frame, and held there by the compression of the seat lug, and having the saddle clipped to its upper end. More commonly, however, a horizontal tube pointing forward is brazed to it, and carries the saddle, for which a backward and forward adjustment is thus obtained. 64. The Saddle. The saddle normally consists of a pear-shaped piece of leather, suspended upon metal springs; the sharp forward end is known as the peak; the rounded rear end is riveted to a plate called the cantle, which is secured to the springs.

The most usual type is the "Hammock" shown upon the bicycle in Fig. 1. Here the framework consists of two or more long springs running from peak to cantle, and secured midway by a clip in the method shown in Fig. 8. The tension of the leather is regulated by a rather inaccessible nut just under the peak; the Brampton has a circular hole in the front of the peak for the insertion of a screwdriver-an excellent plan. In that type of saddle in which the leather is mounted on a rigid frame, bolted to an independent arrangement of springs, the tension of the leather in the frame is generally regulated as described above. Some considerations on the adjustment of the saddle are given in paragraph 12. Detailed directions follow under Fig. 8. 65. The Driving Gear. - Motion is communicated from the cranks through the crank axle, front chain wheel, and chain to the back chain wheel (part of the free-wheel clutch), which drives the back wheel and so causes the machine to move forward. Furthermore, by varying the size of the two chain wheels, or, what is the same thing, the number of teeth on each, we can regulate the number of revolutions that the back wheel will make to each revolution of the front chain wheel, e.g., if the back wheel be 28 in. in diameter, and the front and back chain wheels have respectively 54 and 18 teeth, the rear wheel will make three revolutions to each revolution of the pedals, which are equal to the revolution of a wheel 84 in. diameter: thus the machine is geared to 84 in., thereby covering 22 ft. of ground at each revolution of the pedals.

Remarks on the relative advantages of high and low gears will be found in paragraphs 21, 22, and 23; the rule for calculating the gear of a machine is to multiply the number of inches in the diameter of the back wheel by the number of teeth on the front chain wheel and divide by the number of teeth on the back chain wheel.

Thus: 54 18 = 84.

If the machine be fitted with a gear case, measure the distance covered by it during one revolution of the pedals and divide by 3. If the machine has a free-wheel it must be wheeled backwards.

Abroad gearing is always expressed in this latter way, i.e., by the distance covered at each revolution of the pedals. A machine is said to develop (développer) so many metres. This is a convenient way of expressing gearing, as it conveys more meaning to the average person than does the invocation of the ghost of the old ungeared bicycle by referring to an imaginary wheel of 84 in. to express the fact that the machine travels 22 ft. at each revolution of the cranks. a 66. Chain-line. - This is the distance in straight line from the middle of the hub to the middle of the chain, i.e., it consists of half the width of the hub, half the width of the chain, and the whole of the space between them.

To attach the crank.-Fit it on to the axle, pressing it in and twisting it round till it comes flush. If it goes on very stiffly a tap with a mallet will drive it home. Then turn the crank upon the axle till the flattened side of the axle is parallel with the key-way, and a clear way can be seen through, and insert the cotter. Then drive the cotter quite home with a hammer, taking care to hold firmly against the opposite side of the crank-boss a heavy mass of metal, e.g., a large hammer or a flat iron. This will take the weight of the blow off the crank axle; if this precaution is neglected the axle and the bearing may be seriously injured. When the cotter is quite home, a washer is placed over the other end, which is provided with a screw, and a nut is screwed home against the crank. This nut is only intended to prevent the pin from getting loose, and any attempt to tighten the crank by it will only result in stripping its thread. If the crank is found loose, drive the cotter tightly with a hammer and screw the nut home; if it still remains loose a new cotter is required. If, when the cotter is driven home, the length of screw is insufficient to permit the proper tightening of the nut, put over the cotter an extra washer.

To detach the crank this process is reversed, a smart blow on the reverse end of the cotter releasing it from the hole, when the crank may be twisted off. The best method is to slack the nut so that it projects over the end of the cotter, and, placing a punch against the cotter, give it a smart blow; the nut will keep the punch in place. In emergencies, the nut thus projecting may be struck with the hammer; but remember that to hit the unprotected end of the cotter will ruin the threads, and the nut will not afterwards engage with them. 67. The Crank Bracket and Bearing. The crank bracket is a tubular case or shell of metal forming a portion of the frame, and containing the ball bearings upon which runs the crank axle. [CYCLING 68. The Crank Axle is a solid steel shaft of about in. diameter, turned with cones for bearing purposes (see Fig. 16). It carries at its extremities the cranks and, just inside the right crank, the front chain wheel.

The Rudge-Whitworth Crank Axle is described under paragraph 70. 69. The Cranks are bars of steel usually rectangular in section, but occasionally oval. At the end remote from the axle they are pierced with a hole for the attachment of the pedals (see para. 77), and near the axle they broaden into a rounded end or boss. This is pierced with a circular hole to admit the axle, the end of which is flush with the outside of the crank. To secure one to the other, a keyway is cut transversely to the axle through both of them. Into this is fixed a tapering cotter pin, which, when driven home, secures the crank in place; this keyway (as, of course, also the cotter) is circular in section with one flat side, so that the axle presents a flat surface on one side for about in. The distance from the centre of the crank boss to the centre of the pedal axle is known as the throw of the crank. For remarks on the subject of crank-throw see paragraph 22. Directions for attaching and removing cranks are given under Fig. 9. a 70. A different arrangement is adopted on the Rudge-Whitworth. The crank axle is continued and bent at right angles to form one of the cranks. Its other end is provided with flutes or grooves. These engage the boss of the chainwheel and the second crank, both of which are similarly fluted. Instead of the adjoining faces of the crank and chain-wheel boss being flat they are provided with large coarse pitch teeth, which present to each other spiral surfaces. As a result, when the nut on the end of the axle is tightened up the crank is forced toward the chain-wheel which is prevented from going further along the axle by a projecting shoulder.

Consequently the boss 1S forced in one direction against the flutes on the axle, and the crank is forced similarly in the other direction. Thus both are held absolutely firm and concentric. The axle has as its extreme end a short threaded projection. A nut (mentioned above), roughly semi-circular in section, is screwed on to this, and bears upon a recess countersunk in the crank boss at the end of the hole which admits the crank. The nut, which is flush with the crank boss when screwed home, is provided with notches, by which it can be turned. This device has the merit of eliminating the awkward projection of the cotter pin. 71. The Chain and Chain Wheels. The chain wheels must be exactly in line with each other, or else the teeth will not engage cleanly with the chain, but will rub against its sides, and a great deal of unnecessary friction and uneven wear will result. Much depends upon the degree of tension of the chain, as if it is too slack it may swing from side to side, and, refusing to engage with the teeth, may mount over them and cause an accident, whilst, on the other hand, an over-tight chain will greatly increase the friction of driving and will wear out the teeth. As the chain tends to stretch, or rather to increase in length, owing to the wear of the rivets and rollers, means of adjusting it are necessary, and this end is attained by allowing the back wheel, and with it the back chain wheel, to be moved backwards and forwards in the back fork ends. The exact method of adjustment is described under Fig. 10. 72. The Front Chain Wheel is permanently attached to the crank. The rim which carries the CYCLING] teeth is often made detachable, being secured by bolts to the spokes and hub, so as to admit of a ready change of gear. 74. The Chain. -The construction of the chain will best be understood from the annexed illustration. The distance between the central points of two adjacent links (A to A in Fig. 13) is called the C D A B G E A F is a plate pierced with a hole in its centre to admit the axle b ; rom one side of this plate projects a screw G, which passes through a cap D covering the tips of the fork ends A. Over this screw is screwed a small nut E, and when this is screwed up against the cap D it pulls the screw G, and with it the plate A and the axle B, further towards the tip of the fork ends, increasing the distance between the two chain wheels and so tightening the chain.

By slacking the nut E, we allow the axle to be pulled a corresponding distance into the fork ends, and so loosen the chain. This process, of course, has to be performed separately for each side of the axle.

The method of adjusting the chain may be summarised as follows :- The chain when rightly adjusted should show a very slight deflection from a straight line, in fact the very slightest that will allow it to run freely. This must be judged by spinning the wheel. If the chain is allowed to hang in a kind of festoon it, as we have said above, is highly dangerous Roughly speaking, the ends of the cranks should have a quarter of an inch play.

Then To adjust the chain, slack the large nuts B, that hold the axle in the fork ends; to loosen or tighten the chain, slack or screw up each of the small nuts E, taking care to adjust both sides equally. Half a turn of the nut will make a surprising difference; pull the axle home so that the small nut bears on the cap D, then see that the wheel is perfectly equidistant from both of the back stays; should it incline to one side, slacken that side or tighten the other, as accords best with the right adjustment of the chain. Then cautiously screw the nuts on the axle ends moderately tight, taking care in doing it not to force the wheels to one side; if the wheel remains still central, finally tighten the nuts, and, lastly, screw the small adjusting nuts well home. If you have cone adjusting hubs see that you do not disturb the adjustment of the back wheel bearing in loosening or tightening the fork end nuts (see para. 85). It is difficult in the case of a free-wheel machine fitted with an opaque gear-case to tell when the cranks have the proper amount of play. In such cases it is best to tighten the chain as far as it will go, and then to give a complete turn to the adjusting screw to slacken it. A different method of chain adjustment is by means of an eccentric.

The block above will show the construction, and the directions for adjustment are given beneath it. 73. Free Wheels.-On fixed wheel bicycles the back chain-wheel is a solid ring screwed to the back wheel hub. On free-wheel bicycles this solid ring is replaced by a clutch. The mechanism of this clutch will be understood from the attached illustration. The clutch is formed of two halves moving upon each other. The outer part carries the ordinary chain-wheel teeth, and has internally three or four pawls. The inner portion has a corresponding ring armed with ratchet teeth, which, when the rider pedals forward, engage with the pawls and so drive the back wheel, with which it is of a piece. When the rider ceases pedalling, or pedals at a rate slower than that at which the machine is running, the inner ring overruns the outer, and the pawls slide over the ratchet teeth. A ring of balls is carried by the outer half, and these come into work when the wheel is running free. This bearing is not as a rule adjustable. It occasionally happens that the clutch fails to drive the machine when pedalling is resumed. This is usually due to the pawls having become clogged with dust or stale oil, and this can be cured by swilling out the clutch with paraffin through its lubricating holes. It is important to attend properly to the oiling of the clutch, which often suffers from neglect in this respect, and is in consequence unjustly blamed. The pawls are usually kept in contact with the ratchet teeth by small springs.

In some clutches the outer portion carries the ratchet teeth and the inner the pawls.

BRIT. PATENT 29980/97 BSA FIG. 11.

BSA Loosen the step or nut on the hub spindle on the left side of machine, then the nut on the right side. Then with a spanner turn forward the square end of the hub spindle to tighten en the chain, or backward to loosen it. Hold the square end firmly with the spanner, keeping the cams and blocks in close contact, then with another spanner tighten the left-hand spindle nut or stop. Lastly, tighten the right-hand spindle nut. The cams should be fixed on the hub spindle as shown in the illustration above, i.e., with the ends abutting against the fixed cam blocks. pitch of the chain. Half an inch is the most usual pitch, but some chains have a five-eighths pitch. The gauge of a chain is the length of the D E PAP. № 4727,180 A A B roller. It varies from three-sixteenths of an inch to one-eighth of an inch. The gauge does not affect the strength of a chain; in fact, a narrow gauge chain is stronger, as the rivets are shorter, and there is less tendency for them to bend.

The rollers which bear on the teeth of the chain wheels are of hardened steel, and run on rivets, which are mild steel, either case-hardened or protected by a bush of hard steel. The side plates are of mild steel. The ordinary method of detaching the chain is shown under Fig. 13.

A A To detach the chain. -Get the screw bolt and nut on one of the gear wheels: remove the nut and unscrew the bolt (taking care not to lose them). The chain will then come apart.

To replace. Place the chain in position and bring the ends together on one of the chain wheels: thread the bolt through the side plates and block, screw it home and secure it with the nut: the last usually comes on the inside.

Chains in Gear Cases -Before removing the bolt secure the penultimate links with wire or string so that they can easily be recovered from the case: even if the chain is itself removed this method will save much time in rejoining it: this should be done on the back chain wheel.

To shorten the chain, two links must be removed. The reason why the links can only be removed in pairs will be understood by studying the illustration. Unless the cyclist be a good mechanic, this work is best given to a professional repairer. Chains are best provided with two detachable links placed next but one to each other, so that in the event of a pair of links having to be removed, this can be done without interfering with a rivet. Some chains are locked by means of one of the side plates, which has at one end the hole which receives the rivet opened into a slot.

By swinging this plate on the rivet to which it is permanently fixed it is disengaged by the rivet embraced by the slotted end. The rivet can then be slid out of the roller and the chain removed.

The rivet is best turned by means of the key provided by the makers. 75. Care of the Chain. -No machine that is habitually used on the road should be without a gear case. If you have no gear case, cover the chain with vaseline, or, better still, molten tallow (black lead is terribly messy), and do not wantonly interfere with any moderate accumulation of dust, which will form a protecting crust. When the chain gets too foul to run sweetly (as it will probably do after a bath of liquid mud) immerse it in paraffin for a night, and carefully work it about in the oil, paying attention to any stiff links; then replace it and lubricate as before.

A dirty chain will often run tight and require readjustment, owing to grit getting under it and raising it from the gear wheels. Riders who do not possess gear cases will do well to keep a second chain for use while the first is in pickle.

A dirty gear case should be cleaned out with paraffin. 76. Gear Cases, although they are something of a nuisance when adjustments have to be made, should be regarded as indispensable for ordinary road use.

There are many varieties, but they fall into two classes: rigid cases of metal or celluloid, and lace-up leather cases stretched on a metal frame; the former are infinitely superior for excluding dust and retaining oil, but the latter will keep off all the mud, and most of the dust, and can be knocked about with comparative impunity; this is detrimental to metal cases. [CYCLING Metal cases, again, fall into two classes, fixed and detachable; in the former the central part of the case is soldered to the machine, access to the chain and chain wheels being obtained by removing a large plate in the front portion, and a quadrant-shaped section at the back. In the latter the whole case can be removed if desired; this, however, is a serious business, and is only resorted to in the case of an accident to the machine.

Such cases should always, like the fixed cases,. be provided with a hinged quadrant at the back to give access to the chain and back hub. If they have not this they should be rejected. Otherwise the lubrication of the chain and free-wheel is certain to be neglected, and the detachment of the back wheel is made unnecessarily difficult.

The fixed case is undoubtedly the best for pre-- venting the entrance of dust, and it allows of the chain being run in a bath of oil, to its great benefit, and that of the free-wheel. The oil bath is, however, a nuisance when the machine is inverted for tyre repair.

Into the intimate structure of gear cases we do not propose to enter the mechanical reader will find it out for himself; the unskilled reader will let it severely alone. 77. The Pedals take the work of the feet, and consist of a metal framework, running with ball bearings upon a spindle, which is carried on the end of the crank. The frame may carry rubber or felt blocks, or the feet may rest direct on the framework; pedals of the latter type are called rat-traps. The bearings are almost always coneadjusting, and are of the type shown in Fig. 15. A dust-cap is not infrequently placed over the adjusting cone. This must be removed before the pedal can be adjusted.

All good pedals have the spindle encased in light metal tube to exclude dust, and should be. provided with oil-holes. Pedal bearings are par-- ticularly liable to get choked with mud, and require an occasional rinse out with paraffin. Attention may here be drawn to the featherweight rustless pedal made by the Lea Francis Co. All the exposed parts, which are made of steel, are coslettised. (See para. 116.) The rest of the frame is of aluminium. 78. Attachment of Pedals-These invariably screw into the crank ends, the right pedal having a right-hand thread and the left pedal a left-hand thread, so that the tendency in riding is to screw them home tighter and not to unscrew them.

The pedal is provided either with a flat to allow its being gripped by a spanner or with a slot at the end of its spindle to admit a screwdriver.. (See Fig. 14.) 79. The Wheels, which are shod with pneu-- matic tyres, consist of a hub connected by steel wire spokes with a rim of wood or metal.

The hub revolves on ball bearings upon an axle held rigidly in the frame, thus receiving the weight of the rider and machine, and is sus- CYCLING pended from the rim by means of the spokes which happen to be uppermost. This is termed a Suspension wheel, as opposed to an ordinary carriage wheel, the spokes of which are in compression. But as the bicycle does not remain stationary, the spokes have yet another kind of strain to undergo. In the back wheel the whole of the driving power is applied to the hub, and thus communicated through the spokes to the rim and tyre. For this reason modern wheels are not spoked radially, in which case the pull on them would be at right angles to the direction of the spokes, and would tend to cause the hub to break away from them (to say nothing of the loss of power), but the spokes leave the hub at a tangent (or nearly so), and the pull is thus communicated from the hub to the rim along the direct line of the spokes. For this reason the tangent wheel, as it is called, is immensely stronger than the old-fashioned radial or "direct" wheel, which has long since passed out of practical cycling. are A A B B C case the fork ends should be countersunk to receive washers placed on the spindle. These must, of course, be removed before the wheel can be detached.

To remove the back wheel, take off the sliding end of the gear case, undo the chain, slacken the fork end nuts, when the spindle and with it the nuts, washers, and chain-adjusters may be slid out of the fork ends. To replace it reverse the process, taking care to fit the chain-adjuster (see Fig. 10) well on to the fork ends. 82. Rims are made of steel, of aluminium, or an alloy, or of wood. Steel rims are the strongest, but, of course, are liable to rust. They should be plated, and then enamelled, with the exception of a small strip left with the plating exposed to take the wear of the rim brakes. Aluminium rims are rustless, but they will in time, unless D B A' A B The cups A A' are fixed into the case of the hub B; in these are placed the balls, which are held in place by the cones cc'; of these c is of a piece with the spindle D, but c' is free, working upon the threaded end of the spindle to allow of adjustment. To take the bearing to pieces. -Remove the fork end nuts, slide or spring the wheel out of the forks and lay it on its side with the free cone c' uppermost. We can now unscrew the free cone c', and, holding the other end of the axle firmly in place, tip the balls out of the cup A'; place the hand under the cup A and remove the spindle, when the opposite balls will fall into the hand.

To put the bearings together.-Lay the wheel on its side with the cup A uppermost; put the spindle D through the hub with the fixed cone c uppermost, place the balls in the cup, and let the cone c fall upon them; then, holding the spindle firmly in place, turn the wheel over so as to rest on the end of the spindle nearest to c. The balls may now be placed in the cup A' (the screwed end of the spindle will keep them in place); lastly, screw the free cone c' down upon the balls; when it is screwed home the wheel may be set upright. To proceed to details: the hub is furnished on each side with a flange, generally pierced transversely with holes for the reception of the spokes, which are headed, and, passing through the holes in the flange, take a sharp turn and run to the rim, where they screwed into a brass nipple; this nipple protrudes through the rim, but is prevented from passing through it by a broad flange, which bears on the hollow bed of the rim; the tension of the spoke is regulated by turning the nipple, the spoke being thus drawn further or less into the rim. Upon the correct tensioning of the spokes depends the truth of the wheel, the natural shape of the rim being of less importance than that imparted to it by the pull of the spokes.

The intersections of the spokes are usually tied with thin wire, though the advisability of this is by no means certain. The spokes are thickened (butt-ended) where they pass through the flange, as well as where they are threaded to screw into the nipple.

To adjust the bearing. When the wheel is in place, slack the nut E' (the opposite nut need not be touched), grip the flattened sides of the cone c' with the open spanner provided, and screw it up as far as it will go, then unscrew it about a quarter of a turn and screw up the nut E; take the wheel by the rim and see if there is any perceptible side shake in the bearing; if there be none, and the wheel runs freely, the adjustment is correct; if there be any perceptible shake, screw up the cone a little; if the wheel runs stiffly, slacken it off. It will be noticed that tightening the nut often tightens the bearing also, and for this allowance has to be made. If the proper spanner be not available, the cone may be turned by twisting a piece of string round it, taking the ends in the hands and pulling them tight. The cone may readily be forced round. 80. Size of Wheels - Most machines are fitted with two 28-in. wheels; it is urged by some that a 30-in. front wheel gives better steering, but we scarcely think that it is worth its weight.

We do not recommend 26-in. wheels even for short riders. The increased vibration as compared with 28-in. wheels is very noticeable, and is not sufficiently compensated by the saving of weight or the increased strength of the wheel.

Moreover, the pedals are brought nearer to the ground, and the risk of catching them on stones is very real. 81. Removing the Wheels, To remove the front wheel, take off the nuts and washers, and, pressing with the thumbs upon the hub, spring the fork ends one by one over the end of the spindle. To replace it, reverse the process.

It is much better to choose a machine which has the holes in the fork ends converted into open slots so that the wheel can be removed without the necessity of springing the forks. In such kept clean, oxidise, and may disintegrate. The care, however, necessary in keeping them in condition is much less than that required by steel rims. Wood rims are not suitable for detachable tyres, and are, in virtue of their superior resiliency, used by fast riders in connection with tube tyres. (See para. 145.) They should be varnished at intervals of a few months. 83. Bearings. A bearing occurs where any part of a machine, which rotates, bears upon another part which does not rotate, or vice versa.

A ball bearing is one in which the two bearing surfaces, instead of running directly on each other, are separated by steel balls; thus instead of the friction of one level surface upon another we have only the friction of small points of these surfaces against the balls, and to a large extent rolling friction is substituted for sliding friction. The most usual type of ball bearing consists of two cones affixed to the ends of a spindle and resting upon balls, which themselves bear upon cups contained in the case of the bearing. These may be divided into two classes: (a) where the cups are stationary, and the axle and cone revolve, e.g., the crank bearing; or (b) where the spindle and cone are fixed and the cups revolve, as in either wheel.

This distinction is, however, of no great importance, as with slight modifications any description of one type will equally apply to the other. 84. A more important distinction for our purpose is based upon the method of adjustment of the bearings. For a bearing to run freely it is D A G G A is the case or shell of the bearing and is called the crank bracket; B, the crank; v, the crank axle; E, one of the cones (of a piece with axle); F, one of the discs (or cups) fitted with flat to give grip to spanner; G, locking ring to lock disc against bracket. NOTE. The above locking arrangement (though very good) is not of the usual type; see Fig. 17.

To take to pieces. The following directions apply primarily to the crank bearing, but with slight modifications apply also to the hub. Detach the crank B and the other crank (not shown) which carries the chain-wheel; and the chain-wheel (see Fig. 9); undo the locking arrangement (in this case the locking ring G) and unscrew the left hand cup; if the cup adjusts by means of holes in its outward surface, this is done with a pin-hole spanner; if it is provided with a shoulder (as above) use an ordinary open spanner. When the cup, and with it the balls, are withdrawn, the axle D and the balls of the. other side will come away, leaving only the chain-side cup in position; do not remove this unless necessary; if you must do so, make a file mark across the case of the cup and the case of the bearing to make sure of your replacing it in exactly the same position; otherwise you will set the chain-wheel out of line. The cup may then be removed by undoing the locking arrangement and screwing it out.

To put together. First screw in the chain side cup (if you have removed it) to the exact position it previously occupied, as indicated by the file mark (an error of a whole revolution is not likely to be made, and may be guarded against by counting the threads, which, before removing the cup, lay outside the bracket). Lay the bicycle on its chain side, and put the chain end of the axle D through the cup (there is always more space outside the cone on the chain end of the axle than on the other). Drop the chain side balls into the cup and let the cone of the axle fall on them. Next very carefully turn the machine over, pulling on the chain end of the axle while so doing to nip the balls between the cup and cone to prevent them escaping; with the same object, when the machine is turned over, keep the opposite end of the axle supported.

Take the other cup: fill it with vaseline and place the balls in a ring inside it, taking care not to warm them or the cup, or the vaseline will melt; then very gingerly pass it upwards over the downward end of the axle and engage it in the threads of the bracket, screwing it home very gently, especially as the balls begin to approach the cone, or they may over-ride one another and jam. When the cup is screwed home, replace the chain-wheel and cranks and adjust the bearing.

To adjust. Slack the locking ring & or its equivalent; apply an open spanner to the shoulder of the disc or cup F, and loosen or tighten till an adjustment is made (see directions under Fig. 15). If, as is usual, the disc has pin-holes instead of a projecting shoulder, turn it by inserting into the holes the prong of a pin-hole spanner; in emergencies, the disc may be cautiously driven round with a long nail and a hammer. necessary that the balls should not be so tightly jammed as to prevent their revolving, nor th the bearing should be so loosely put together as to admit of the balls running out of their proper circular track; to ensure this it is necessary that we should have some means of regulating the distance between the cup and cone.

To attain this end we may move the position of either the cup or the cone, and the most convenient and accurate way of doing this is by providing one or other with a screw thread en- [CYCLING gaging with some other portion of the machine, which for running purposes is of a piece with it, and securing it to that portion by some locking arrangement.

We may accordingly divide ball bearings into two classes. (a) Cone-adjusting bearings, in which one cone screws upon the axle, and the cups are fixed in to the case of the bearings. (b) Cup-adjusting (commonly called discadjusting) bearings, in which the cones are immovably fixed to the axle and the cups (discs) screw into the case of the bearing.

C The head bearing of the modern safety is of a different type, and is described under Fig. 5. 85. (a) Cone-adjusting bearings. From the diagram in Fig. 15 it will be seen that by unscrewing the cone we alter the relation not only of c' itself to the cup A but that of the cone c to the cup A. When the required adjustment has been obtained, the cone c' is fixed in place by screwing up the nut E, which drives the washer F against it. 86. (b) Cup- (or disc-) adjusting bearings.- In these the cones are permanently fixed to the axle, and the cups screw bodily into the case of the bearing (see Fig. 16). It will be seen that the cup and cone respectively, necessarily face opposite ways to what they did in the cone-adjusting bearing, and this has the effect of placing the ball races further apart. The locking arrangement is, BRACKET.

To loosen slacken the nut, and loosen or drive out the cotter as described under Fig. 9. in the case of crank bearings, usually of the character described under Fig. 17. For hubs it is commonly of the type shown in Fig. 16. (See Fig. 17a.) A description of the cup-adjusting crank bearing and hub is given, together with full instructions for their manipulation, under Figs. 16 and 17. 00 0 00 87. Comparison of the two types. We consider cup-adjusting bearings preferable. Firstly, they are more dust proof. In each type there is space for the entrance of dust between the cup and the coned axle: but in the cup- CYCLING] adjusting bearing this is only the size of the diameter of the axle itself; in the older type it is the size of the diameter of the whole cone, and this can only be mastered by complications in the way of dust caps, &c.; secondly, for the same reason, it is oil retaining; and, thirdly (in the case of hubs), the bearing can be adjusted without disturbing the fork end nuts and so possibly the chain adjustment. Fourthly, the same disc-adjusting bearing allows for the same length of axle a slightly greater distance between the ball races. There is, however, apart from these incidental advantages, absolutely no essential difference in the running of the two types, and a good cone-adjusting bearing is far better than a bad specimen of the other. 88. Care of the bearings. As we have shown above, careful adjustment should be made when necessary; the rider should, however, refrain from tinkering with the bearings more than he can help, especially from taking them to pieces. Nuts which are always being tightened and slackened cannot be expected to hold. In fact, no part of the machine should be touched unless it really calls for it.

The best way of testing the running of a wheel bearing is to put the valve of the tyre towards the top of the wheel, and see that its weight causes the wheel to oscillate backwards and forwards till at last the valve settles down at the very bottom of the wheel. If the bearing is unevenly worn a perfect adjustment cannot be effected; the best compromise possible should be made; it is better to put up with a little shake in the bearing than to hinder the free running of the wheel; but if a worn bearing is run too slack the wear is only exaggerated. The just mean is to be learnt only by experience.

In the case of the back wheel of a machine fitted with a free-wheel, the wheel will not oscillate; it will, however, stop running very gradually. The bearings should be oiled with good lubricating oil, say once in a hundred miles or so, and then but sparingly. Oil should not be left lying round the oiler, as it attracts dust; if, however, a ring of dust is found around the entrance to bearing it is better not to remove it, or at all events very rarely, as it is very likely to be rubbed into the bearings, especially if they are the coneadjusting variety. A piece of chenille lightly wound round the axle where it emerges from the bearing will go far to exclude dust. Disc-adjusting bearings may be oiled more copiously, and much less often.

If from any cause the bearing should become clogged, it should be slackened and paraffin injected; it should then be spun round, fresh paraffin being added till it runs out perfectly clean; the bearing should then be adjusted, left to run dry, and oiled. It is a good thing to have a hole fitted with a screw plug drilled in the bottom of the crank bracket for the escape of the paraffin. 89. The Step is usually a roughened prolongation of the left-hand back fork end nut, but is occasionally brazed on to the back stays. 90. Change-speed Gears. All the changespeed gears on the market are of the epicyclic type. The essential elements of these gears in common use are: (I) a central or sun pinion on the spindle, which (at all events when the gear is working) is fixed; the sun wheel is in mesh with (2) number of planet wheels (ordinarily four) mounted by means of studs on a disc called the planet-carrier; and (3) an internally toothed wheel independent of the planetcarrier, but in mesh with the planets which it a encircles. If the planet-carrier be made to rotate, the planets would, but for the presence of the sun pinion, rotate idly upon it; but as they are in mesh with the immovable sun pinion which acts as a fulcrum, they are forced to revolve upon their studs, and as they are in mesh with the encircling internally toothed wheel, they force that also to rotate, which it does in the same direction as the planet-carrier, but at a speed increased in the proportion of the number of teeth on the internally toothed wheel to the number on the sun pinion. If the internally toothed wheel be made to rotate, it will impart its motion to the planets, and they, being in mesh with the immovable sun pinion, can do nothing except force their carrier to rotate, which it does at a speed diminished in the same proportion. It should be added that one of the commonest devices for putting the gear out of action is to set the sun pinion free to revolve on the spindle. The object of a change-speed hub is to cause its shell which carries the spokes and so drives the back wheel to move at a faster or slower speed than the chain ring which is driven by the chain. Consequently, the chain ring is mounted, not as in a plain-geared bicycle direct on the hub shell, but on a driving sleeve (or driver) which, through an intermediate mechanism of the type described above, communicates its motion, accelerated or reduced, to the hub shell. All these contrivances have arrangements by which the special gearing can be put out of action, and the motion transmitted without change of speed from the chain ring to the hub shell. There are similar devices by which the speed imparted by the cranks to the crank axle can be increased or diminished before it is transmitted to the front chain-wheel and so by the chain to the back wheel of the bicycle. 91. Two-speed Gears are naturally simpler in construction than three-speed gears, and are therefore described first. One of the simplest two-speed hubs is the Eadie, shown in Fig. 18.

EADIE A B Here the sun wheel A can be slid along the hollow spindle by the actuating mechanism (of the same type as that described in para. 98); when it is to the left, the teeth engage with the internal teeth of the detaining pinion C, which is a fixture on the axle. In this position, then, the sun wheel is immovable. The chain ring is mounted on the driver B, which terminates to the left in the internally toothed ring, which is, of course, in mesh with the planets. These are mounted upon the deep flange of the hub (which serves as planet-carrier). The planets are in mesh with the immovable sun or fulcrum pinion, and force the hub to rotate slower than the chain ring. Thus the low gear is obtained. To obtain the high gear the sun pinion is slid to the right, where, always remaining in mesh with the planets, it engages in teeth (not shown in the illustration) in the driver, and driver, planets, and hub are thus locked together, and rotate as a solid mass, as if the special mechanism did not exist. This is called the normal gear, and it will be remarked that it is the higher of the two. The low gear offers a reduction of 238 per cent. from the normal gear. 92. The Villiers Gear (see Fig. 19), is even more simple, and differs from the Eadie in that the normal gear is the lower, and the extra mechanism is brought into play to obtain the high gear. In this case the sun pinion does not slide on the spindle. [CYCLING mechanism can lift this pawl out of mesh with the ratchet plate, or, being relaxed, allow it to be carried by its spring into position for engagement with it. When the ratchet plate and sun pinion are thus held, the planet-carrier (which The planet-carrier is borne on the driver, and the internally toothed ring is formed on the hub flange. Consequently, the hub is driven at a greater speed than the driver.

The sun pinion is free to revolve on the spindle, but can be locked to it by means of a sliding sleeve on the spindle, actuated by a rod which runs through it. This sleeve engages by teeth at its end with teeth on the end of the sun pinion. When the sun pinion is thus locked, the gear works as described in para. 90, though in this case the hub is driven at a higher speed than the driver. When the sun pinion is released, the gear revolves as a solid mass at the speed of the chain wheel and driver. The high gear is 33'3 per cent. above the normal. There are numerous other hub two-speed gears, e.g., the Manchester hub and the Fagan.

The 93. The Sunbeam Two-speed Gear differs from these foregoing, in that it is applied to the front chain wheel instead of to the hub. The normal drive is on the low gear, and the special mechanism comes into play on the high. Its object, of course, is to enable the chain wheel to rotate at a different speed to the crank axle.

This is effected in the following manner. crank, which is fixed to the axle by the usual cotter, carries a hollowed flange about two-thirds of the diameter of the chain wheel. This hollowed flange is the planet-carrier, and carries three planets. The chain wheel is free to revolve relatively to the axle, and carries the internally toothed ring, which is, as usual, in mesh with the planets. The internally toothed ring is cut on its outside with ratchet teeth, which engage with spring pawls mounted on the planet-carrier. The sun wheel is of a piece with a plate called the ratchet plate, which has two ratchet teeth. These two parts together are free to rotate on the axle, but can be held in place by a spring pawl mounted on the shell of the crank bracket. The actuating is borne by the crank) drives the internally toothed ring through the planets at an increased speed, and with it the chain wheel, which overruns the planet-carrier by means of the ratchet and pawls mentioned above. When, however, the ratchet plate and sun wheel are free, the epicyclic train is thrown out of gear, and revolves as a solid mass, when the ratchets and pawls communicate the motion of the crank and planetcarrier to the chain wheel. The gear gives a rise of 333 per cent. above the normal. 94. It will be observed that if the internally toothed ring were borne by the crank, and the H J E K A G E N FB A D M R (DISSECTED).

L planets mounted on the chain wheel, the gearing would be down instead of up, and the normal gear would thus be on the high speed. The Centaur Cycle Co. and the James Cycle Co. have gears constructed on this principle. Each of these gears gives a reduction of 25 per cent. on the low speed. 95. The special advantages of bracket gears are: (1) that they allow of the parts being made larger and therefore stronger than in the case CYCLING] of hub gears, and (2) that they are capable of being fitted to tricycles equally with bicycles.

Hub gears can only be fitted to tricycles by the clumsy contrivances of transmitting the drive from the front chain wheel to the gear (mounted on a suitable support), and again from that by means of a second chain to the driving axle of the machine. 96. Of three-speed gears, the Sturmey-Archer is the oldest and best known, and perhaps the simplest. On it the low gear is 23 per cent. below the normal, and the high gear 31 per cent. above it.

The mechanism may be described as follows:

The references are to Fig. 21 and Fig. 22, the former showing the gear dissected, the latter showing it assembled. References to the former are in letters, to the latter in numerals.

This ring has a flange which forms one ball race of the bearing between the hub and the driver (see above).

Lastly, there is the end piece of the hub (19 L), which screws into the hub-shell. In this is the cup for the bearing at 4, and a deep recess with internal pawls (20 M). 97. The gear acts as follows: The gear-cage is free to slide upon the sun pinion with which the planets are in mesh. Its position upon the sun pinion is determined by a thimble (N) projecting from a threaded sleeve (0), which is carried on the spindle and is free to slide upon it. This thimble is controlled by a spring carried in the spindle (which is hollow), and is connected to the spring through a slot in the spindle. This spring is itself compressed or relaxed by the actuating mechanism of the gear. A nut (R) LOW GEAR:

I NORMAL GEAR. 4 MICH GEAR. 19 20 0 2 19 14 15 9 16 13 17 ווי 12 8 10 18 8 5 6 7 3 1 5 The spindle (I A) is hollow (the reason for which is explained presently), and carries, immovably fixed to it, the sun pinion (2 B), a fixed cone (3 C), and an adjustable cone (4 D).

The chain ring (5 E) is screwed to the driver (6 F). This revolves on the fixed cone of the axle (3 C) on a detachable ring of balls (7) contained in a detachable ball-cage. The driver is cut with ratchet teeth upon its side, and clutch teeth upon the end remote from the chain. It has mounted upon its exterior next to the chain ring a ball race (8G). Upon these revolves the body of the hub (9 H), into which is screwed the complementary ball race to that at 8 G.

The next member of the gear-the gear-cageis shown at II I. The two broad rings and the neck connecting them are of a piece. The narrower of the two rings (that nearer the chain) has on its exterior and interior surfaces spring pawls (12 J and 13 respectively). The broader flange is internally toothed, 14 I (the internally toothed ring of para. 90). Mounted in it and contained in it, but free to revolve in it, is the planet-carrier (15) -a flange bearing four studs on which run the four planets (16). The planets are always in mesh with the internally toothed ring. The four studs have their chainward ends shaped so as to form clutch teeth, and the other face of the flange, i.e., that remote from the chain, carries, projecting from the gear-cage, a ring with external ratchet teeth (17 K).

The hub-shell (9 H) has screwed into it at its chainward end a ring bearing ratchet teeth (18). screwed upon this threaded sleeve locks the gearcage to the thimble, which thus carries the gearcage with it. When the spring is entirely relaxed, it carries the thimble and gear-cage into the position for the low gear.

The low gear is obtained when the gear-cage is moved to the extreme left. The ratchet teeth on the side of the driver engage with the pawls on the interior of the narrow ring of the gearcage. The drive communicated from the chain ring to the driver is thus transmitted to the gearcage, of which the internally toothed ring is part. The internally toothed ring is in mesh with the planets. As these are also in mesh with the immovable sun wheel, they drive their planetcarrier at a reduced speed (see para. 90). The moving of the gear-cage to the left brings the ring of ratchet teeth which projects from the planet-carrier into mesh with the pawls in the end piece of the hub.

Thus we have a drive from the chain ring through the driver to the internally toothed ring, thence geared down through the planets to the planet-carrier, and so to the hub-shell.

For the medium gear the gear-cage is pulled to a central position. The pawls of its interior surface remain in mesh with the long ratchet teeth of the driver; but its external pawls are brought into mesh with the ratchet teeth on the interior of the hub-shell, and thus driver, gearcage, and hub-shell are locked together and revolve as a solid mass. The gear is thus normal. For the high gear the gear-cage is moved to the extreme right, and its internal pawls slide out of the ratchet teeth of the driver on to the smooth surface beyond on which they have no hold. The toothed ends of the studs, however, which are borne by the planet-carrier, are brought into mesh with the corresponding teeth at the end of the driver, and the planet-carrier is thus made to revolve. Then, by the reverse of the action described for the low gear, the internally toothed ring is driven by the planets at an increased speed. In this position of the gear-cage its external pawls engage with the internal ratchet teeth of the hub-shell to which the geared-up motion is thus transmitted.

It will have been noticed that on each speed a ratchet and pawl clutch forms part of the drive. When the rider ceases to pedal, the pawls overrun the ratchets, thus affording an independent free wheel on each speed. The whole of the bearings of the hub are adjusted by the cone (4 D) in the manner described under Fig. 15. As the actuating mechanism enters the spindle from the right-hand side, the controlling spring is naturally fixed on the left-hand side, and when tension on it is relaxed, it pulls the gear-cage to that side. When the planet cage is to the left, the gear is low, and thus, when the spring is released, the low gear naturally comes into action.

This is important, because the spring may get released by the actuating mechanism being damaged, and in these circumstances the rider is left with a gear on which he can at least go anywhere and do anything. In some gears it is the high gear which in such circumstances comes into play, and this means that the bicycle will, in conditions of heavy going, be almost unrideable. It is a pity that few, if any, gears run back automatically to the medium. (The Sturmey- Archer coaster hub mentioned below is one of the exceptions.) 1 LOW HIGH NORMAL STURMEY ARCHER 3 SPEED GEAR MARKX a.

STUR MARKX 3SPER NORMAL b. a. For Top Tube. b. For Handlebar. 98. Actuating Mechanisms (Fig. 23). There are several varieties of these, but the following description (applicable to the Sturmey-Archer) will give a general idea of them. They may be obtained in two types of fitting, according as the [CYCLING controlling lever is mounted on the top tube of the bicycle or on the handlebar. In the former case the commonest arrangement consists of a lever which is slid over a quadrant, on which holes or stops are provided to arrest the lever in the proper positions for the high, low, and medium gears. This lever pulls a wire cable, and is carried on pulleys round the angles of the frame to the hub or crank bracket. The wire bears usually a small chain, which in its turn conveys the motion to the spring in the hollow spindle (see para. 97). Handlebar controls are of the type illustrated in Fig. 23b. The motion is usually conveyed from the lever by a Bowden wire (see para. 109) to the top tube, where it enters a clip and joins the ordinary wire cable described above. 99. Adjustment of Controlling Wires. It is important to have the wire properly adjusted, as otherwise the mechanism controlled by it in the gear does not mesh properly. The following directions apply primarily to the Sturmey-Archer, but many other gears are adjusted in the same way. The rider must get the special directions for his particular gear. An indicating rod emerges from the left end of the spindle (see Fig. 22). The end of this is usually flush with the end of the axle on the medium gear, projects about in. beyond it on the low gear, and retreats the same distance within it on the high gear. The end of the spindle is usually covered by the step, but this is hollow and provided with an aperture through which the indicator can be watched. The wire is adjusted as follows: The lever is placed for the middle gear when the wire should be a little slack. Exact adjustment is obtained by screwing or unscrewing the milled nipple on the end of the small chain, or by loosing the front clip on the tube or the top tube control, and tapping it along the tube (a lazy method and destructive of enamel), till the indicator is flush with the end of the spindle. When the adjustment is right for the middle gear, it is right for all the gears.

There are some eight three-speed gears on the market, but considerations of space render it impossible to describe them. They differ from the Sturmey-Archer in important details. Some use two planet-carriers and sets of planets; in others it is the sun pinion which is moved to change the gear; others, again, have the planets-at a possible sacrifice to their stoutness and consequent strength-mounted on ball bearings. We hope, however, that the description given above will enable the reader to understand the general principles on which these gears are constructed. 100. Change-speed Coaster Hubs. By a combination of the types of mechanisms described above and under para. 112 are produced coaster hubs with two or three gears. We regret that space prevents a description of these ingenious contrivances. 101. The Pedersen Three-speed Gear. We regret that it is impossible to do more than mention this interesting and efficient gear, which is not of the epicyclic type. A secondary shaft is carried in a boss of the hub, and changes of gear are obtained by bringing pinions on the main shaft of the hub into mesh with pinions on the secondary shaft. The ratio of gears is high, the high gear being 50 per cent. above the normal, and the normal 50 per cent. above the low. 102. Brakes. The relative advantages from the riding point of view of hand-applied or footapplied brakes are discussed under para. 19. From the mechanical point of view they are most conveniently considered according as (1) the retard- CYCLING] ing force is applied (a) at the rim or (b) at the hub; and (2) the actuating force is transmitted through (a) a visible train of levers and bell cranks, (b) an invisible Bowden wire, or (c) the chain. As rim brakes are the most generally used it is best to treat of them first. 103. Rim Brakes in General. The machine is checked by the application to the inner side of the rim of a pair of blocks made of a suitable composition, and held in metal shoes from which they are detachable. The shoes are carried on the arms of a stirrup, and the whole brake is put into action by being pulled against the rim by a set of rods and bell cranks or by a Bowden wire operating on the stirrup. The stirrup usually ends in guides which slide in sockets clipped to the forks. The brake is released by a spring which takes it out of contact with the rim. As the brake blocks wear by friction with the rim, an adjustment is provided by which this wear may be compensated by bringing them nearer to the rim. 104. The Brake-shoes are open at the rear end, and the blocks can, when it is necessary to replace them, be forced out, and new ones similarly inserted. The shoes are closed at their forward end, and the blocks are driven firmly into THE TATE LIBRARY, BRIXTON, S.W. method of transmission is by a Bowden cable (see para. 109). The great value of the Bowden cable lies in its simplicity and in the accidental fact that it is the only brake on the market which conducts the actuating force from place against them by the force of the moving wheel when the brake is applied.

It is very desirable to have brake-shoes which can readily be removed so as to allow of the removal of the wheel, or to facilitate tyre repairs. How this is done is shown in Fig. 24. It is surprising that contrivances of this kind are not more general. 105. Visible v. Invisible Brake Connections.- The transmission of braking force to the front wheel is a very simple matter, and there is little question but that the ordinary arrangement of rods and levers as shown in Fig. 25 is the best.

The transmission of force to the back wheel is much more difficult. It may be effected by a train of rods and bell cranks, such as is shown in Fig. 26. This arrangement, which is now the most usual, has the merit that all the parts are exposed to view, and that the rider is not at the mercy of a wire cable concealed in a conduit, which may break suddenly without any warning to the rider. On the other hand, it may well happen that the vibration of the road may cause one of the numerous screws in visible brake work to loosen and fall out, without the rider being any the wiser till he tries unsuccessfully to apply the brake. Moreover, visible connections are apt to get loose and rattle, and are comparatively troublesome to keep clean. The alternative