Chain network

9-fach pinion package model R9 (Dura Ace - compatible) of the company SRAM
a resignation hub from the 50's with three pinions for a chain network

as chain network one designates a mechanical transmission with bicycles, with that several gear rims next to each other is arranged and by shifting the driving chaindifferent courses to be inserted can. This can both on the crank side (to three gear wheels) and on the wheel side (until ten gear wheels) to take place. The advantages of the chain network are in the simple structure, the low weight and a high efficiency (in the comparison to the hub circuit). Disadvantagesare a short life span, a high maintenance need and a contamination risk for the bicycle driver. Since the chain holds two up to three thousand kilometers with normal use however, if you occasionally one cleans and one regreases, and there in addition meanwhile covers for the circuit are, relate themselves thoseDisadvantages and therefore is the chain network the usually-used circuit for bicycles.

The chain network consists itself of the Umwerfer, which switches the front chain sheets, the switching device, which switch the rear pinion package, as well as the chain, which are held by the Kettenspanner course, therethe necessary chain length for each shifting process changes.

Switching device with long Kettenspanner (also “cage” mentioned) at a Mountainbike

most chain networks can be switched today indicated, i.e., there is a defined position of the shift levers for each possible gear wheel. Chain networks are both usual in combination with hub circuitsas also as exclusive switching possibility. Dependent on the targeted application of the bicycle circuits with 22-44 teeth Mountainbike ( usually three-way) or 30-55 teeth racing cycle ( doubly 34-50, 39-53 or three-way) are used in front. In the back the number of the pinions up to ten, with numbers of teeth from 11 varies to34 teeth. (Racing cycles often only to 21 or 25). With three chain sheets in front and ten pinions in the back 30 courses would be theoretically adjustable. Due to the high wear and noise however a part of the courses, with which the chain runs particularly diagonally, is not recommendable. In additionsome courses are almost identically and therefore doubly present in their translation. Here z results. B. during 27 course circuit a number of 14 (!!) usable and/or. material courses.

Manufacturers of chain networks are for example companies such as Shimano and Campagnolo, those those todaystill standards set and other companies such as SRAM (in former times well-known than Sachs) or FSA.

The switching course is operated from a shift lever or a rotary switch. This rotating motion is transferred over the push pull cable to the switching device that then implements the shifting process. Chain networks lead the chain inSwitching device around two Kettenrädchen. The chain guide sheave is laterally swivelled by a parallelogram by push pull cable for the shifting process, so that the led chain of a pinion arrives at the next. In order to adjust the length difference (larger pinions need more chain length than smaller) is a chain idler belowthe chain guide role platziert. This around the storage axle of the cage is swivelled and of a return spring strained, thus that the same track tension is always present, all the same across which pinion the chain straight is led.

In this simple principle to today only few changed and neverthelesshave the chain networks an almost rapid development thrust behind itself, which settles particularly in the refinement of the shifting process. It began more than 20 years ago with the first index circuits („positron “of Shimano and „Comander “of Sachs).

Up to that time were the chain networks nearlyreserve excluding the sport cyclists. Because it applied to move the stepless shift lever sensitively exactly so far, until the chain on the next pinion wrapped around. Because at that time no grid was present and was not adapted also the pinion form yet the chain movement, had even first easily overthe actual course outside to be switched, in order to then take after resting upon the chain on the pinion the shift lever back again easily. With the grid (called indexation) the shift lever could manage this now also the normal cyclist. There it initially nevertheless still strongly ratterte to the chainthe switching function mastered, had the climbing procedure on the next pinion to be constantly further improved.

Switching parallelogram

the technical break-through succeeded 1984, when Shimano took over the diagonal parallelogram of Suntour with the Dura Ace circuit. With a so-called diagonal parallelogram arranged diagonally around approximately 25 degrees the swiveling way that runsSwitching rocker not only inward, but at the same time also downward. That corresponds once to the climbing movement of the chain, on the other hand follows the switching rocker of the pinion embankment. Wants to be called: The further the circuit swivels inward, all the the chain guide role continues to turn downward and holds therebythe waiting for that inward more largely becoming pinions almost constantly. A second return spring finally guaranteed that all the same with which tooth differences the pinion package is equipped the distance from the upper Kettenrädchen to the pinions always between 1 1/2 and 2 1/2 track links amounts to. Now is again the optimal condition for the next switching step. Because this distance larger, takes place the course change only zögerlich, since the laterally mobile Schaltungskette can turn itself too far. If the distance is too small, the chain guide sheave on the pinions can sharpen.

The next innovative advance revolutionized thoseBicycle world: With their „hypermember “- tooth profile makes for Shimano possible in the year 1988 a switching even under load and came the Mountainbikern straight quite, because there are situations again and again with sudden upward gradients, in which only one course change can protect the stop of the Rades. Ingenious the thisTooth profile: The chain does not have to climb now to the course change no more over the tips of a tooth away on the next pinion, but it overflows, reaching tooth into tooth from a pinion on the next. Around this to reach once the depth of teeth was drastically shortened, on the other hand thatGap from tooth to tooth tub-shaped increases and in the long run „overflow places “production: In the places, in which the teeth of the neighbouring pinions stand next to each other (this situation is with pinions with a tooth difference once, with two teeth difference twice and with three teeth accordingly three times etc.the case) is continued to reduce the depth of teeth (it to see nearly like broken off teeth out, which leads quite often to surprise of unaquainted ones). In addition here the teeth are laterally flatter, so that the chain can run here diagonally from the one on the other pinion.

Further one more elementarilyA component of the chain network is the Umwerfer.

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