On a chain-driven motorcycle, engine power reaches the rear wheel through three parts: the front sprocket, the chain and the rear sprocket. This trio works together, wears together and is usually replaced together. A worn set loses power, causes jerking when changing gear and opening and closing the throttle, and in the worst case the chain jumps off or breaks. With regular maintenance a set lasts a very long time; for that, see our chain maintenance guide. In this article we explain when the set should be replaced, how you can tell, and what to look out for when choosing a new set.
\n\nA well-maintained chain set can generally last 20,000–30,000 km; if neglected, this drops to half. The main factors that determine life:
\nThe teeth of a new sprocket look symmetrical with rounded tips. As they wear, the teeth lean in the direction the chain pulls, the tips become pointed and take on a wave or hook shape. If you see this look on the rear sprocket, the set has reached the end of its life. The front sprocket wears faster because it is small and engages more often; do not forget to check it too.
\nTake hold of the chain at the rearmost point of the rear sprocket (the 3 o'clock position) and pull it backwards. If the chain clearly separates from the sprocket and more than half of the tooth tip is visible, the chain has stretched.
\nA new chain stretches a little in the first kilometres, then stays constant for a long time. If you have to adjust it every few hundred kilometres, the chain is nearing the end of its life.
\nIf the chain adjustment marks on the swingarm have reached the last position and the chain is still slack, the chain is past its replacement limit.
\nIf, while slowly turning the wheel, the chain is tight at some points and slack at others, or the links do not straighten out but stay kinked, it shows that the inner pins have rusted and the seals have deteriorated.
\nRattling from the chain while riding, and a feeling of \"slack\" when accelerating and when closing the throttle, are early signs of set wear.
\n\nFor a more accurate check, many owner's manuals give a service limit for the length across a certain number of links (or pins). You take the measurement with the chain taut, for example with the bike in gear and the rear wheel pushed lightly backwards, or on the upper run of the chain. If the value you measure exceeds the limit in the manual, the chain should be replaced. If your manual has no such value, ask a workshop to measure.
\n\nThe chain and sprockets wear to match each other. If you fit a new chain to a worn sprocket, the new chain has to conform to the worn tooth profile of the old sprocket and stretches much faster. Fitting an old chain to a new sprocket gives the same result. That is why the general rule is: the front sprocket, rear sprocket and chain are replaced as a set. The set seeming expensive at first is generally cheaper than the total of replacements made separately.
\n\nChain size is expressed with a three-digit code:
\n428 is common on small bikes and 125s, 520 and 525 in the mid-range, and 530 on some big bikes. Your bike's chain size, number of links and sprocket tooth counts are written in the manual or on the side plate of the old chain. Changing the size requires changing the sprockets too.
\n\n| Type | Feature | Use |
|---|---|---|
| Unsealed (standard) | Cheap, low friction, short life; needs frequent lubrication | Small and light bikes |
| O-ring | Protects the grease inside the pins with rubber rings; long life | Most mid-size and big bikes |
| X-ring and similar | Seals of different cross-section, less friction and long life | Powerful bikes, long trips |
When cleaning sealed chains, do not use petrol, thinner or high-pressure water; the seals get damaged. Use only cleaners and lubricants suitable for sealed chains. For chain care products, see the chain care page.
\n\nSome riders change the tooth count of the front or rear sprocket when replacing the set to adjust acceleration or motorway revs. Taking one tooth off the front sprocket or adding one to the rear increases acceleration, raises the revs on the motorway and can increase consumption. This change can also throw off the speedometer and odometer. If you are not sure, stay with the original ratio.
\n\nAccording to our site's equipment data, chain and sprocket set prices in Turkey range roughly from 833 to 2,450 ₺ at the economy level, 2,981 to 5,332 ₺ at the mid level and 6,804 to 10,353 ₺ at the premium level. The difference comes from chain type (sealed or unsealed), size and brand. Recommendations are on the chain and sprocket set page.
\nReplacement requires the right tools and torque values, as it involves undoing the front sprocket nut, removing the rear wheel and riveting the chain. If you do not have the equipment, leaving it to a workshop is safer. When buying a used bike, the condition of the set is an important bargaining point; details are in the used bike checklist.
\n\nWhat really determines the life of a new chain set is the maintenance in the kilometres that follow. In the first few hundred kilometres after the new set is fitted, the chain stretches slightly; check the tension in this period and adjust it if needed. Then move on to a routine of regular cleaning and lubrication. Your throttle use matters too: hard launches, wheelies and sudden throttle on and off put shock loads on the chain. Smooth throttle and correct gear choice protect both the chain and the tyre.
\nRear wheel alignment also directly affects the life of the set. Relying on the adjustment marks on both sides when setting the tension is not always enough; on some bikes these marks are not precise. If you see the chain running onto the sprocket rubbing from one side, or a shiny wear mark forming on one side of the sprocket, have the alignment checked at a workshop. In rainy and salty seasons, drying and lubricating the chain more often prevents rust forming and the links seizing.
\n\nHooked teeth, a chain that lifts away from the rear sprocket, frequent tension adjustment and a used-up adjustment margin show that the chain set is due for replacement. Replace the three parts together, confirm your bike's chain size and number of links from the manual, and make the new set last with regular maintenance.
\n\nWell-maintained sets generally last 20,000–30,000 km; on neglected sets this can halve. Decide by tooth shape and chain stretch rather than km.
\nIt is not recommended. Worn sprockets stretch the new chain in a short time. The front sprocket, rear sprocket and chain should be replaced together.
\nA chain size with a pin pitch of 5/8 inch and a roller width of 1/4 inch. Common on mid-size motorcycles.
\nOn mid-size and big bikes an O-ring or X-ring chain is standard and lasts much longer. On small and light bikes an unsealed chain can be used but needs more frequent lubrication.
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