A bicycle drive terrain is mostly classed as a consumable part by cyclists. Parts will need to be changed as and when they wear out and as with most mechanical wear the sooner you notice a part is past its best the cheaper it is to put right.
The most commonly replaced drive terrain item is the chain. This is because of the sheer amount of stress and wear this one item gets. The chain is almost in constant use. It only gets a rest when you’re flying downhill at speeds that surpass your top cadence and we all know those good times don’t last anywhere near as long as we want them to.
So when should you replace update your drive terrain? Unlike other bike components there is a hard and fast rule to updating these components. If you’re into home maintenance we highly recommend that you invest in a chain checker. This tool will tell you exactly how worn your chain is. 70% worn means you need to replace your chain. 100% worn means you’ll have to replace your chain as well as your cassette.
Once you’ve replaced 70% worn chain for the third time you should replace your cassette.
Other factors may affect wear and the efficiency of your drive terrain such as derailleur alignment, Gear combinations, and cleaning schedules.
Firstly derailleur alignment has a huge influence on the wear rate of your major drive components as well as shifting performance. When the chain leaves the front chain ring and leads back round to the rear mech it needs a smooth transition on to the cassette to minimize wear, mechanical drag and noise. A slightly bent mech cage, derailleur or mech hanger will prevent this so check alignment regularly particularly if you regularly ride off-road.
Even with good alignment all riders should be conscious of their gear combinations. This only applies to riders with double and triple front derailleurs. You might have heard the term big to big or small to small, essentially this refers to a gear combination which could be achieved using a better combination of gears. Lets say that you’re big to big (the largest chain ring on the front and the largest cassette sprocket on the rear) if you look at your chain in this gear combination it will probably be bent. A better way to achieve this gear might be to drop two or three gear on your cassette and move from the top to the middle on the front mech. The chain will have straightened out significantly using this combination and consequently your entire drive will wear less and last longer.
Finally regular maintenance and cleaning are a best way to delay wear. Dirt combined with oil creates a brilliant grinding paste. Removing excess dirt on a regular basis and re-applying oil will make shifting much better and slows down any mechanical wear to a minimum.