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Guide to Upgrading your Bicycle--Chains



A clean, well-lubricated chain should last for 3,000 to 5,000 miles before it stretches so much that it needs replacing, so most cyclists buy a new chain about once a year. You can make a nice little improvement in shifting performance by buying a premium chain to match your gear train, rather than a $3 economy model.

Indexed shifting has changed the chain market. There used to be dozens of chain makers and chains were interchangeable. Any chain could be used with any gear train. Today the chain is an integral part of a gear shifting system. Most bicycle stores now carry the recommended chains for Shimano’s and Sun- Tour’s indexed gear trains and perhaps Sedisport and Regina CX-S chains for the racers. There’s hardly any market left for the little old chain makers.

Chain Development

Hans Renold invented the roller chain in the first bicycle engineering boom of the 1880s. The addition of a free-turning roller to the older pin-and- bushing chain greatly reduced noise and power losses. A well-lubricated roller chain wastes only about 1½ percent of the power transmitted. Chain drives are efficient, reliable, and economical—which is why they’ve survived for so long.

Chain design stagnated as long as bicycles had only one gear. You could use a century-old chain on a current 1-speed bicycle and never tell the difference. Derailleurs added two special requirements. The chainwheels and sprockets weren’t aligned in most gears, so derailleur chains had to bend ‘or deflect sideways, and chains had to be derailed from sprocket to sprocket and from chainwheel to chainwheel.

The first major design change took place in the 1950s when narrow 3 “derailleur” chains were developed to replace standard 1/8-inch 1-speed chains. The 2-inch chain was more flexible and it allowed the use of five-sprocket freewheels. Three sprockets were the limit for ‘/8-inch chains.

Chains changed significantly in the late 1970s. Narrow-spaced freewheels were developed along with narrow chains. At the same time, Shimano and Sedis introduced the Uniglide and Sedisport chains with their funny-looking bulged side plates. The Sedisport chain also used special inner plates to get rid of the bushings. (Figures 1 and 2 show the difference between a conventional and a bushingless chain.) These three changes kicked off the current generation of modern derailleur chains. Now different chains are designed for different gear trains and few cyclists interchange chains any more.

Terminology:

I call the standard-width 2-inch derailleur chain a “wide” chain, and the narrow 32-inch derailleur chain a “narrow” chain. I won’t talk any more about extra-wide, 1/4-inch, 1-speed chains.

Chains for Indexed Shifting

When Shimano and SunTour set out to design indexed shifting, repeatability was the overriding requirement. The indexed shift lever moves the cable, and the cable moves the rear derailleur jockey pulley a constant distance for each click. Therefore, the rear shift has to occur at the same place each time. An indexed shifting gear train is designed around a specific rear derailleur freewheel-chain combination.

Each maker came up with a different design. Shimano designed SIS for flexible, early-shifting narrow chains. SunTour designed AccuShift for stiffer, late-shifting narrow chains. Campagnolo provides indexed shift levers and you pick the chain to match the rear derailleur and freewheel. You don’t have to use the chains that Shimano, SunTour, or Campagnolo recommend, but if you use a different chain, then the shifting performance is your responsibility.

A chain that shifts very well with friction shift levers may not shift properly with the same freewheel and rear derailleur using indexed shift levers. This is particularly true with AccuShift. Sedisport and Narrow Uniglide chains shift well with current SunTour gear trains using friction levers, but not with AccuShift levers.

How the Chain Affects Shifting

In section 4 on indexed shifting, I told you about the rear derailleur, freewheel, chain, and shift lever interactions, so I won’t repeat that information again. Instead, let’s look at how chain design affects shifting, with or without indexed shift levers. The chain is involved in both front and rear shifting. You shift on the rear more frequently and chain design affects rear shifts more than front shifts.

In order of importance, crisp, positive rear shifting depends upon the following factors:

• The design of the rear derailleur.

• The shape of the freewheel sprockets.

• The spacing between freewheel sprockets.

• The tooth difference between adjacent freewheel sprockets.

• The design of the chain.

In order of importance, smooth, positive front shifting depends upon these factors:

• The design of the front derailleur.

• The tooth difference between the chainwheels.

• The spacing between the chainwheels.

• The design of the chain.

This suggests that chains don’t matter very much, which isn’t quite true. The chain is an essential part of the shifting system. The wrong chain can make a good gear train shift less crisply. The right chain is like icing on the cake, making a good gear train shift beautifully. However, even the best chain can’t salvage a gear train with poor derailleurs and freewheels. Incidentally, good chains and poor chains cost about the same.


FIGURE 1 Parts of a conventional chain.

Chain Performance Testing

I’ve been mucking about with gear trains for more than ten years. It’s taken that long to put chains into perspective. In 1980,1 had to stay home for three weeks while recovering from an operation. I couldn’t ride my bicycle or do anything strenuous so I amused myself by using the derailleur testing machine to investigate differences between chains. I spent about 150 hours testing various permutations of chains, rear derailleurs, and freewheels. Then I spent about 20 hours writing my first chain article. The sweat-to-intellect ratio was higher than anything before or since. I gave some general recommendations in that article, but I didn’t completely understand the chain’s role in the complex rear-shifting mechanism. I could see what was happening, but I couldn’t explain why it was happening.

I ran a similar series of tests for this section. This time, I understood the Interactions better so my goals were better defined. Basically, I checked the performance of six integrated gear trains: Shimano narrow-range, Shimano wide-range, SunTour narrow-range, SunTour wide-range, Campagnolo narrow- range, and Campagnolo wide-range. The Campagnolo wide-range is typical of old-fashioned (pre-mountain bike) touring gear trains. The Campagnolo narrow-range is typical of old (pre-indexed shifting) racing gear trains. These six gear trains make up about 90 percent of all the applications.


FIG. 2 Parts of a bushingless chain. Plate; roller; outer plate

TABLE 1.Test Chains

TABLE 2. Chain Test Equipment: Gear Train; Rear Derailleur; Freewheel; Width; Sprockets

I used the 11 chains listed in table 1. They include the 6 chains recommended by Shimano, SunTour, and Campagnolo for their indexed shifting gear trains, 4 popular and widely available premium chains, plus the HKK H-1480 chain, which is a conventional, low-priced derailleur chain.

I tested the chains in the same fashion that I test front and rear derailleurs. For the rear shifting chain tests, I used the gear trains listed in table 2. I tested all of the gear trains, except the Campagnolo racing, with both conventional friction shift levers and indexed shift levers. My derailleur testing machine doesn’t measure front shifting performance very precisely. However, I can observe the significant differences between good-shifting and poor-shifting chains.

To get a rough measure of front shifting chain performance, I set up a Sugino Aero Tour crankset with 52/47/24 chainwheels and a Shimano Deore XT front derailleur. I removed all of the friction from the shift lever and made repeated shifts back and forth between the three chainwheels. In addition to the machine measurements, I’ve noticed that wide chains are a bit less inclined to ride on the gap between the chainwheels than narrow chains.

Table 3 shows the results of the 66 chain tests. It evaluates shifting performance with friction shifting levers and indicates which chains do not work properly with indexed shift levers. (For more information about front shifting, see section 8 on front derailleurs.)

Chain Features

All of the differences in chain performance result from three design features: flexibility, width, and sideplate shape.

Chain Flexibility

A 1-speed chain is always perfectly aligned, so it doesn’t have to be flexible. A derailleur chain must bend sideways (deflect) in most of the gears. In the cross-chain gears (big sprocket—big chainwheel or little sprocket-little chainwheel) the deflection is about an inch. The chain is noisy and inefficient in the cross-chain gears and most riders avoid them, especially on racing bicycles with short chainstays. A flexible chain gives less problem with deflection.

Flexibility can be either good or bad, depending on the rear derailleur. Chain flexibility works with the rear derailleur’s chain gap (jockey pulley-to- sprocket distance) to provide precise shifting. A stiff chain needs more distance. A flexible chain needs less distance.

The Sedisport and the Shimano Narrow Uniglide chain have a unique bushingless construction that’s very flexible. In general, worn chains are more flexible than new chains, which is why new chains often shift differently than worn chains.

With indexed shifting, the designer has to know the flexibility of the chain. I measured flexibility by laying a brand-new chain on its side on a V8-inch-thick plate and pushing it over the edge one link at a time. A flexible chain could only be pushed out three links (1½ inches) before it sagged 1/8 inch. A stiff chain could be pushed out six links. I show three ratings in table 3: flexible, intermediate, and stiff.

Chain Width

If your bike has a wide-spaced freewheel, you can use either a wide or a narrow chain, but best shifting performance usually comes from a narrow chain. If you have a narrow-spaced freewheel, you must use a narrow chain. Both wide and narrow derailleur chains have a -inch gap between the inner plates. The wide and narrow categories are determined by the length of the pins. Narrow chains are less than 10 percent narrower than wide chains, but the spacing between the sprockets of a typical narrow-spaced freewheel is reduced from 3.5mm to 2.7mm, or 23 percent. Most of the narrowing comes from reducing the clearance between the chain and the sprockets.

You can tell quite a lot about a chain with a caliper. The key widths listed below are shown in FIG. 3 and are listed for each chain in table 3.

TABLE 3. Chains: Make and Model; Cost; Weight; Width; Rear Shifting Performance

Pin Length

The pin length tells you if the chain can fit in a narrow-spaced freewheel. It also tells you how far the chain can bend before the pins hit the adjacent freewheel sprocket. Narrow chain pins are 7.4mm long, or less. Wide chain pins are typically about 8mm long.

Outer Plate Width

The width of the outer plate is most important when subtracted from the pin length, because protruding pins catch onto the teeth of chainwheels or sprockets and help shifting. Wide-spaced outer plates make the chain stiffer. Many of the better-shifting chains have bulged or flared outer plates. Flaring the outer plates exposes a wider gap to the teeth, but it also shields the protruding pins.

Outer Plate Gap

Wide outer plate gaps have more room to catch the corners of the sprocket or chainwheel teeth.

Inner Plate Width

The width of the inner plate affects flexibility. The difference between the outer plate gap and the inner plate width also affects flexibility. The bulged inner plate is a unique feature of the Sedisport chain. The inner plate is flared out, which helps shifting.

Inner Plate Gap

The width of the gap between inner plates measures how readily the chain will fall onto a smaller chainwheel when you shift on the front.

Chain Sideplate Design

Until 1977, all chains looked very much the same. The inner and outer plates were flat little dumbbells. With the introduction of narrow chains, the makers got the idea of widening the center of the plates to improve the chain’s shifting ability. Now almost all of the premium chains have some kind of special plate shape. I think this is a bit like tire treads. It looks more important than it is. The key items are still width and flexibility. However, widened outer plates do improve front shifting. They also tend to marry certain chains to certain free … is Shimano’s twist-tooth free-…

Four sideplate variations can be found among the chains listed in TABLE 3. The outer plates can be bulged out, the inner or the outer plates can be flared out, the inside of the plates can be chamfered, or the bottom of the plates can be cut away.

= = =


FIG. 3 Chain dimensions.

B — outer plate width

C — outer plate gap

D — inner plate gap

E — inner plate width

= = =

Chain Tensile Strength

For my 1980 chain article, I tore the chains apart with a tensile test ma chine. I haven’t run tensile tests on the new chains and I don’t show the old test results. I think all chains, even the least expensive, are more than strong enough. For example, assume that a strong racer can push on the pedals with a 250-pound force. That’s a 500-pound tension on the chain. The weakest chain that I tested in 1980 had an ultimate strength of 1,600 pounds. Chains don’t stretch from tension. They get longer because of the wear of the pins, bushings, and rollers.

Chain Lubrication and Longevity

I’ve generally avoided maintenance topics in this guide, but I can’t resist this one. I didn’t test chain longevity, but I’m convinced that chains wear out because of dirt and rust. Cleanliness and lubrication are the keys to long chain life. The definitive article on chain wear was written by Don Pruden in the February 1977 issue of Bike World. Don measured chain stretch after pedaling a series of chains 1,000 miles or so, using 11 different chain lubricants. He concluded that the best lubricant is paraffin wax. I agree and I’ve been touting wax since I read the article. You heat it up to about 300°F on top of your stove. Wax has about the same flash point as cooking oil, so take the same fire precautions as you do making french fries.

The hot wax gets in between the pins, bushings, and rollers, which are the only places where lubrication is needed. Once the chain cools off, the wax on the outside is hard. In fact, it quickly flakes off, so the chain doesn’t attract dirt. I wax my chains every 300 miles or so, more often in wet weather.

Chain Makers

Just half a dozen makers sell quality chains in the aftermarket. There are another dozen or so makers of standard bulk bicycle chains.

HKK

HKK (Hokoku Chain Sales Co.) cooperated with SunTour and Fuji in the development of the narrow-spaced freewheel and the companion narrow chain. HKK made SunTour’s early narrow Ultra-6 chains. The current HKK Z-Chain is a bit wider than a narrow chain and it’s designed for wide-spaced freewheels. It has deep chamfers on the outer plates. The Z-Chain and HKK’s Spirit chain are included in SunTour’s list of recommended chains for wide-spaced 5- and 6- speed AccuShifts. The HKK H-1480 is a typical conventional derailleur chain. I used the HKK H-1480 for all of my old front and rear derailleur tests because I wanted a completely average chain. I include it to give you a “standard” chain for comparison.

Regina

Regina is the old favorite of the racers. They make eight different chains but only three or four are widely distributed. I ran the full series of tests on the wide Oro and Record and the narrow CX-S. I ran a few tests on the wide CX and the narrow BX chains.

Regina was late to develop a chain for narrow-spaced freewheels. By the time they introduced their top-of-the-line CX-S, virtually all of the racers were using Sedisports. The CX-S is an excellent-shifting chain, It’s the only chain that shifts well on both AccuShift and SIS gear trains. The CX-S is asymmetrical and it has to be installed correctly. The inner and outer plates on the inside, and the inner plates on the outside have a deep notch on the bottom to facilitate shifting onto larger sprockets. Regina’s other narrow chains, the BX, Silver BX, and Oro 13X look like conventional wide chains with short pins. They don’t shift nearly as well as the CX-S.

The Regina Oro and Record are classic old designs. They both have over sized inner plates with a narrow gap between the inner plates and a large clearance between the inner and the outer plates. The Record has small outer plates that are drilled for lightness. Neither shifts very well on modern gear trains. The CX is the modern version of the Record.

Sedis

Sedis is now a part of Sachs-Huret, so that the Huret ARIS indexed shifting system will be calibrated around Sedis chains. Sedis introduced the narrow Sedisport chain in the late 1 970s at the same time that Shimano introduced the wide Uniglide chain. The Sedisport was the first bushingless chain, with inner plates punched and upset to form bushings. This construction gives a very flexible chain. The Sedisport has flat parallel outer plates and bulged inner plates. It’s one of the strongest chains made. It really excels on close-ratio, narrow-spaced seven-sprocket racing freewheels.

The Sedisport has completely taken over the professional racing circuit. It’s strong, reliable, and cheap. The professional team mechanics can’t be bothered cleaning and lubricating chains. They buy low-priced, gray Sedisports by the gross and install a new chain before every race.


PHOTO 1 Narrow chains: top to bottom, Shimano Narrow Uniglide (bulged outer plates), Sedisport (flared inner plates), SunTour Superbe Pro (flared outer and chamfered inner plates), SunTour Pro (cutaway inner plates), and Regina CX (cutaway inner plates).


PHOTO 2 Standard-width chains: top to bottom, Regina Oro BX (oversize plates), Sedistraveler (conventional chain), Shimano Uniglide II (bulged outer plates), Regina CX (oversize inner plates), and DID Lanner (flared outer and chamfered inner plates).

Shimano designed their indexed system around two flexible narrow chains: the Narrow Uniglide and the Sedisport. On SIS gear trains, the two chains perform almost the same with a slight edge to the Narrow Uniglide. Sedisports may or may not work well with wide-range touring gearing. It depends on the rear derailleur and the freewheel. The combination of a Sedisport chain, a SunTour freewheel, and an old SunTour single-pivot GT derailleur is a sure loser. The Sedisport chain does not index well with SunTour AccuShift; it shifts too early, but it works fine in the friction mode.

Sedis is delighted to sell you higher-priced Sedisports. The silver or the gold models are identical to the gray model except for color and price. The Sedisport Pro is a nickel-plated super chain with selected links, extra-hard rollers, and extra-strong riveting.

The Sedistraveler is a conventional wide chain with special corrosion protection for mountain bike service. Conventional chains don’t shift well with Shimano or SunTour indexed systems. The pins on all Sedis chains are “Delta treated,” which is their proprietary surface-hardening process.

Shimano

Shimano introduced the Uniglide chain with its characteristic bulged outer plates in 1977. I liked it then and I still like it. When Shimano developed the twist-tooth freewheel sprockets to go with the Uniglide chain, the shifting got even better. For a decade I’ve been recommending the wide Uniglide chain to people with problem gear trains. If it doesn’t help, the gear train probably requires major surgery. The wide Uniglide chain is noisy. Nobody seems to know just why, not even Shimano.

As part of the SIS program, Shimano developed the Narrow Uniglide chain. I call it the “Shimanosport” because it combines Uniglide’s bulged outer plates with the Sedisport’s bushingless design. The Narrow Uniglide shifts better than the wide Uniglide both front and rear and it’s silent.

Shimano now makes Narrow Uniglides in the Dura-Ace and 600 models and wide Uniglides in 600 and UG II models. The Dura-Ace is made from chrome-moly steel and has boron-treated pins.

SunTour

SunTour, Fuji, and HKK invented the narrow-spaced freewheel. (They brought it on themselves, Mrs. Twiddle.) For the first five years, SunTour recommended HKK Z-Chains or the very similar SunTour Ultra chain. The early Z-Chains shifted rather miserably. However, narrow-spaced, wide-range gear trains shift poorly regardless of what chain you use. I must have answered 50 letters on that theme. The Daido DID Lanner chain, which appeared in about 1984, was a better chain for narrow-spaced, wide-range gear trains. The Daido company has never had good distribution in the U.S. aftermarket. All SunTour chains are now made by Daido.

SunTour now sells three fairly stiff narrow chains. The Superbe Pro (SP 6000) and the Cyclone (SP-6100) have similar flared outer plates. The Superbe Pro has chamfered corners on the inside of the inner plate.

The SunTour Pro (SP-6200) has cutaway inner plates, like the Regina CX-S, to allow the sprocket teeth to engage the chain. These two chains are called “Lone Rangers” because the cutaway plate looks like his mask. The SunTour Pro has fewer cutaway plates than the CX-S. The SunTour Pro shifts better on the front and a tiny bit better on the rear than the Superbe Pro. All three SunTour chains have Daido’s “Dai-hard” surface treatment.

= = =


Table 4: Gear Train; Index; Service; Recommended Chains

= = =

A Favorite Chain?

TABLE 3 records the results of many hours spent testing chains. There’s a lot of data in that table. To help make your chain selection simpler, I have prepared TABLE 4, which offers recommendations on which chains are best suited to different gear trains and different types of riding.

All of my bicycles have Shimano Dura-Ace Freehubs with twist-tooth sprockets. The Shimano Narrow Uniglide chain makes beautiful music with this freewheel and it’s on all of the bikes.

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