Shimano 1985 Advertisement — The Shimano Index System: A New Approach to Shifting

[A mostly text page with line drawings of a gear cluster, derailleur positions L1 to L6 and a pulley tooth profile, a photograph of a derailleur, a color photograph of a racing cyclist in a red jersey bending over the handlebars, and a photograph of the Dura-Ace parts group at the lower right.]
New DURA-ACE Technical Series No. 3
The Shimano Index System
A New Approach to Shifting.
BETTER PERFORMANCE THROUGH SYSTEM COMPONENT DESIGN
The development of the Shimano Index System (S.I.S.) started with the realization that not enough attention had been paid to the problem of inefficient shifting in competition situations.
The bicycle racer’s shifting performance is largely determined by his skill level. Shifting efficiency is a result of his “feel” and guesswork. In real race conditions other factors come into play: Fatigue mounts. Attention focuses on tactics, terrain and the competition.
Shifting under these stressful conditions often results in mis-shifts which leave you in the wrong gear or with your chain slipping between gears. In these cases it’s really component function which has prevented you from reaching your full competitive potential.
Shimano believes it doesn’t have to be this way—that’s why we developed the Shimano Index System.
Shifting the conventional multi-speed racing bicycle is similar to finding a station on your car radio by turning the tuning knob. It takes concentration, patience and a deft touch. Most of all, it takes time. Doing it quickly, with any amount of precision is difficult at best.
On the other hand, with S.I.S., changing gears is just like tuning that same radio with pushbuttons. One touch and you’ve got it.
LEVER AND DERAILLEUR—THE SYSTEM APPROACH
To help make shifting more precise the New DURA-ACE shift lever utilizes a click-stop mechanism—the S.I.S. unit. Six preset positions signal gear engagement with a “click” you feel. Each click aligns the rear derailleur with the precise, even spacing of the New DURA-ACE freewheel or cassette.
New DURA-ACE levers don’t lock you into S.I.S., either. Simply turning the shift lever “D” ring allows you to instantly switch between indexed and conventional operation.
The New DURA-ACE rear derailleur was designed along with the lever as an integral part of S.I.S. The basic requirement for precise shifting is maintaining a constant, minimal distance between the rear derailleur guide pulley and each sprocket.
A derailleur must provide two actions. The pulley cage must be moved back and forth laterally along the gear cluster while simultaneously changing the vertical height of the guide pulley to match the cluster profile.
The problem with conventional designs is that the pulley cage is moved across the gear cluster in a straight line parallel, or at a fixed angle, to the hub axle. As the guide pulley approaches the smallest gear (Shown in diagram as L1) it is forced further away from the gear. Overall shifting accuracy and precision suffers, especially when trying to downshift from higher gears.
New DURA-ACE rear derailleurs incorporate Shimano’s unique DOUBLE servo-pantagraph design to create a minimal distance between the guide pulley and gear cluster, regardless of the gear combination.
CENTERON AND UNIGLIDE SPROCKETS.
The Centeron guide pulley was designed to add a precise amount of lateral movement to automatically provide the fine adjustment necessary for perfect chain alignment.
The special Uniglide Twist-Tooth shape of the New DURA-ACE freewheel and Freehub cogs actually guide the chain on and off the gears in a smooth, continuous motion without hesitation or slippage.
UPGRADE WITHOUT OBSOLESCENCE.
As a direct result of the extra levels of performance and precision engineered into New DURA-ACE, all S.I.S. individual components offer improved performance even when used with conventional components.
Functioning as a system New DURA-ACE signals a breakthrough in bicycle shifting performance for all cyclists. Not limited to pure racing applications, S.I.S. also serves the needs of discriminating touring and recreational cyclists who demand optimal shifting performance.
The Shimano Index System is the result of the applied Shimano philosophy of improved component function with real world benefits.
New DURA-ACE racing components have the advantage. The next move is yours.
L1 L2 L3 L4 L5 L6
Easy S.I.S. syncronization with the cable adjusting barrel.
NEW DURA-ACE
See New DURA-ACE at your professional bicycle dealer.
Les Maillots. Get the latest tabloid sized edition of this visually-stunning journal of bicycle competition around the world.
Send $2.00 check or money order to Les Maillots c/o Shimano Sales Corporation.
For a complete technical literature package detailing Shimano’s New DURA-ACE please contact:
SHIMANO SALES CORPORATION 9530 Cozycroft Avenue, Chatsworth, California 91311
SHIMANO®
© 1985 Shimano Sales Corp.