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Fixed Gear Chains 101
Your bike's chain is the heart of the drivetrain, the means by which the motive power you provide reaches the wheel. If you ride a fixed-gear bike ('fix'), the chain assumes the additional function of speed control. And for those insane purists who ride brakeless, the chain is the primary braking system. In short, it may be the most important component you ever buy. Yet, strangely, it is difficult to get hard information about chains. Individual manufacturers publish charts of pin strength and stretch, but no independent body surveys the market on behalf of the consumer. The knowledge to be obtained from shops and magazines tends to be anecdotal, based on limited experience or just plain gossip. Basic questions--How do I avoid breaking my chain? How tight should it be? What's the best chain for fixed-gear use?--often go unanswered. This article is my attempt to improve matters. No breaks? Yanking the bike on a velodrome sprint? Not to worry! 30mph brakeless skid in an 81-inch gear? No problem!! There's good news. If you're riding a fix, the risk of breaking a chain is very low. High-intensity maneuvers put a lot of strain on the bike. I've heard instances of breaking spokes, stems, rear hubs, lockrings. I even know of an NYC messenger who tore the cleat off the bottom of his cycling shoes in an emergency stop, and another who broke a crank in a sprint! But I've never heard of a chain snapping on a fix. To check that my own experience is representative, I posed questions about chain breakage to the fixed gear mailing list, to Susan Huang of the Continental Chain Company (KMC), and to John Dacey, owner of Business Cycles, the highly-regarded cycle shop in Miami, Florida. Everyone said roughly the same thing: chains break only when they're improperly repaired or maintained. The few list members who reported broken chains were quick to add that the chain in question had been rusted, squeaky, dry, or that it was on a geared bike and popped during a shift. Susan Huang said that she'd only ever heard of chains breaking when a master link was wrongly fastened, or when a rivet had been left misaligned after repair. John Dacey commented that even a well-maintained chain might break if it was loose enough to roll partway off the chainring, but he added that this situation, in which a single link is pinned on a gear tooth and subjected to excessive side-pressure, is much more likely on a geared bike than a fix. The straight chainline of a properly set-up fix makes it the best choice for chain integrity. If the chain on your fix is properly installed and maintained, it simply will not break. No throw? A fix will throw its chain only if something else comes loose first. The most common cause is rear-axle slippage, which can occur in bunnyhops, skid-stops and high-rpm descents. Keep your axle nuts tight, and don't even think about using a quick-release on the rear wheel. Other componentry can affect the chain as well. I rode the 2002 NYC Five Boro Bike Tour with a messenger. He was proud of his 25-year-old brakeless fix and the zero-maintenance regime he followed. While we were sprinting through a mile-long descent, he suddenly found himself coasting! His thin-stock aluminum chainring had bent sideways, throwing the chain. We knocked the chainring back into line with a wrench, re-seated the chain, and rolled on. The chain wasn't to blame. And chain stretch? All chains loosen over time. The rivets that hold the chain together develop grooves or indentations at the points where they rotate against the bushings or sideplates. As the rivets wear, the links are able to move back and forth. A good photo of the results appears in Sheldon Brown's article on chain maintenance, referenced below. The results are wasted effort and metallic noises as the misplaced links rub against gear teeth. The best way to combat chain stretch is to change your chain regularly. How often? 'More than you think you should,' is John Dacey's reply. Angelo Betemit, whose shop ANewGen Bicycles is first choice for many of NYC's messengers, comments that replacement frequency depends on how much and how hard you ride. He adds that chains on fixed gear and singlespeed bikes tend to wear faster than their gearie equivalents. Some of Angelo's customers replace their chains four times a year. All about bushings The familiar waisted shape of a chain link is that of its sideplates, one pair to every link. In a conventional chain, a pair of sideplates is joined by bushings, hollow tubes set perpendicular to them. The bushings pass through holes in the plates, flaring slightly at the ends to keep the plate from slipping off. Within the bushing is the solid cylindrical rivet that holds each link to the next. On the outside of the bushing, running between the sideplates, is the roller, the thick, short tube which contacts the teeth of your chainring and cog. See Sheldon Brown's Chain Maintenance page, referenced below,for helpful photos of these tiny parts. In recent years, bushingless chains have become the components of first choice on geared bikes. As the name suggests, these chains lack separate bushings. Instead, the holes in the sideplates are machined to form dome or mushroom shapes. Pairs of plates are joined by short rivets passing through the apexes of the domes. Rollers pivot on the paired domes. These designs offer increased lateral flexibility, making for smoother shifts. Bushingless fixes? As far as fixes are concerned, the jury is still out on bushingless designs. Susan Huang considers them an overall improvement on their predecessors. The bushingless design is lighter and quieter, with no sacrifice of strength. The only disadvantage is a theoretical increase in the likelihood of chain throw. John Dacey hazards a guess that chains with bushings may be slightly stronger than those without. My own experience on track bikes is that conventional chains from Izumi and HKK are the quietest, smoothest chains I've ever ridden. These also tend to be the most expensive models! But I have never had an opportunity to compare conventional and bushingless chains from the same manufacturer. Chains for strength For most fixers, chain strength is not an issue. Perhaps KMC's super-fat 3/16" 415H Freestyle chain really is the strongest chain for all uses. (It's certainly the noisiest, as KMC freely admit.) If you're planning to do the kind of grinding and chainring-bashing maneuvers they do in bike trials, go ahead and buy one. But for low-impact fixed riding, any chain is plenty strong enough, especially if it's made for track or BMX use. As long as you aren't grinding your chain on rocks, curbs, ledges and stairs, it will likely be one of the last things on the bike to break. One very simple way to increase chain strength is to take out the master link. Some Keirin chains come with a small nut-and-bolt-fastened master link, intended to facilitate quick changes between races. John Dacey recommends that these be reserved for track use, as they could come loose during rougher urban or offroad rides. Chains for smoothness Smoothness is hard to define, because it's an absence of problems. A ride that is not smooth may give you the feeling that sand is binding up your drivetrain, leeching energy from your stroke. You may hear creaking, straining metallic sounds as you push. My track buddies call these sounds 'the ol' snap-crackle-pop.' The most important single factor in the quest for smoothness is to run a decent chain. In my 12 years' riding, I've always found track chains smoother and quieter than BMX models. And the more expensive track chains are the smoothest, because their parts are more finely machined. Which should I pick? For fixed gear use, you should always choose a track or BMX chain. If you want low noise and maximum smoothness, then go for a 1/8" track chain by Izumi, HKK or Regina. They are expensive but extremely strong, and they ride like butter. My own favorite is the beautiful, stretch-resistant Izumi Model V, colored gold and black. And it's NJS-approved. NJS stands for 'Nihon Jitensha Shinkokai,' Japan's Keirin-racing organization. If you're on a limited budget, or if you're going to be bashing and grinding off-road with your chainring, then go for a BMX chain. All three of the technical experts I interviewed, Angelo Betemit, John Dacey, and Susan Huang, recommend KMC's Super Duty BMX-Freestyle chains--Z510HX for 1/8" rings, and Z610HX for 3/32" rings. These are described by the manufacturer as 'StretchProof', a quality apparently achieved through a combination of harder rivets and strong inner sideplates. Angelo advises riders with 3/32" drivetrains to avoid Shimano chains as they are made for geared bikes and 'weak.' And on a 1/8" rig, don't use ultra low-end BMX chains, because they run rough and make noise. He adds that the older, pre-SRAM Sachs track chains are very smooth, and that any KMC Z-series chain will be strong. Anything else? The best chain in the world won't give you a good ride unless you treat it right. Here are some maintenance tips to help your chain work better and live longer. Get your chainline as straight as you can Information sources So many variables affect the performance of the chain that no one can keep track of them all. To gather information for this article, I went to several respected sources: The Fixed Gear mailing list
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Writer
Greg Goode wrote FG101, the 63xc.com primer.
Date
v1.0 written October 2002