Cycling art, energy, and locomotion

by Robert P. Scott

ANTI-VIBRATORS AND SPRING FORKS.

The abstract terms of the heading have, so far, generally been applied to certain devices constituting an elastic connection between the standards of the wheels (1), or, more precisely, between the front fork and backbone. The more recent forms of anti-vibrators are (2) the spring hinge about midway in the rear frame, or backbone, of the machine; (3) the spring joints at the extremity of the front fork connecting with the forward wheel axle; (4) the spring fork proper, in which the extensions are either wholly or in part elastic. The last two are, to my mind, the most deserving of praise. In the first named above, the shock is mainly confined to the front half of the machine,—that is, to the front wheel, its fork, and handle-bar,—while in the last two the front wheel alone receives the concussion to the full extent, an intervening spring preventing the transmission of the shock to other parts of the system. When it comes to be fully appreciated by the fraternity that the shock sustained by the machine and rider is not only to be treated as a matter of comfort or discomfort, but that it has other very important claims to our consideration, we may expect it to be more fully discussed. Not that we care so much about the vibration loosening every joint, screw, and pin in the entire contrivance, which makes it worn out, so called, when it has scarcely begun to wear,—of course, in the general march of progress, we expect to remedy that also,—but it is the momentum we are most after. The writer has always been one who has had a constitutional aversion to working up a speed and then having it all knocked out by a stray stone.

The difficulty experienced by inventors in the line of anti-vibrators appears to be, that while acquiring the desired elasticity in the proper direction an elasticity in other directions has followed, making the machine feel unsteady and capricious, especially in the steering. This undoubtedly valid difficulty in the way is worthy of careful consideration before accepting an anti-vibrator; in fact, the very end desired can easily be missed in an imperfect device, as it might, while holding momentum in one direction, lose it in another. I cannot better express my opinion as to the general requirement of a good anti-vibrator than to say, get plenty of spring, but acting in the plane of momentum and gravity, and get it as quickly as possible; that is, at the connection of the wheels with the forks, or at the outer end of the spokes if it can be done without interfering with the rigid transmission of power to the driving-rim.

Recent American anti-vibrator.

It is always difficult to apply any attachment to the driving-wheel of a machine; in the Ordinary it would be beneficial to attach an anti-vibrator to the forward wheel, but as a matter of construction it would be about as difficult to do this as it would be to attach it to the rear wheel of the Safety.

We hope to see and may expect a number of devices to be offered by makers which will fulfil all requirements. Appended find a cut of one recently patented, of which I can speak with some confidence from having used a similar contrivance in experiments in this connection.

The figure here, as in the patent, shows the connecting-rod swinging through an almost useless arc of action, but the general plan is good; not, however, as neat as some others.

A great maker has of late, however, adopted a device which, to my mind, does not fulfil all of the requirements; it is still confined too much to a vertical action, and has really no horizontal amplitude unless the machine is ridden by a very heavy man, in which case the spring will assume a very abnormal position.

Other makers have adopted the joint to the centre of the frame or backbone of the Safety type (No. 2 above), so constructed that the pedals are also provided with a vertical motion; this certainly helps to isolate the man from vertical concussion, and it is good; yet the horizontal give is lacking in these machines, and the front fork, together with the handle-bar, still receives a shock and loses in vibration. Later, an inventor has shown a new pedal in which, apparently, the rubber works upon a spring and has a vertical motion under the pressure of the foot. This is a deserving though a misguided effort. The connection of the man with the apparatus through which the power is transmitted to the machine should be as direct and rigid as possible: all springs should be beyond this point. An elastic pedal is quite a different device from that named in the last preceding paragraph, in which the crank-shaft has a vertical motion and the “connecting-link,” together with the source of power (the man), are all rigidly and inelastically connected together, the whole, as a system, swinging vertically by a spring.