A broken chain can mean the disappointing early end to a ride. You may carry and chain tool and spare pins to repair a chain on the road, but chain wear or “stretch” can cause excessive wear on your more expensive components long before a break. For this reason, some consider chains a regular maintenance item and they are definitely worth keeping a eye on.
What do I check ?
The industry standard for chain dimension is a 0.5inch spacing between pins, referred to as the ‘pitch’ of the chain. A 0.5% increase in this measurement would suggest a chain needs replacing, greater than a 1% increase and the chain is heavily worn and has possibly worn the cassette too.
The chain can be measured using a ruler, or specific tool (all measurements should use a portion of the chain that has standard links, be sure to excluded any quicklink or other ‘joining’ links) :
A new chain would measure 12inches for 12 links (from the centre of one pin to the centre of the pin on the 12th link). So, if this measures greater than 12 1/16 inches the chain should be replaced.
Measuring this value (with the chain under moderate tension) can be a little difficult. There are a number of chain wear indicator tools available – they simply drop-in to the chain and give a basic wear indication.
There is a debate around the design of measuring tools and that many tools many include ‘roller wear’ (that is not significant in chain stretch) aswell as ‘pin wear’ (which is the cause of the chain stretch) in their measurements. You can read the technical details on this issue here.
For our money though, we’ll take the basic CC-3.2 from respected Park Tools :
Available from Amazon here.
How long do chains last ?
This varies substantially, depending on chain type, environment, rider and type of use, with figures quoted anywhere from 3,000 – 15,000km, so checking chains is the only way to see your number.
What replacement chain should I buy / what do I need ?
Firstly, you need to determine what speed chain you need (ie how many gears you have on the back 9/10/11 etc.) as chains are speed specific.
Secondly you need to consider either the brand of chain you currently have, or the brand of cassette you have – Generally, you can mix Shimano and SRAM, but neither will work well with Campagnolo (and vice-versa). KMC are a popular brand and will work across manufacturers, but in all cases, check the product specific information.
You’ll need a chain tool to adjust the length of the chain (and in some cases remove the old and rejoin the new).
Check the GCN video below for more information on the process and some more information on chain links.
NOTE: In the video the new chain is sized by comparing the length with the old chain, if the old chain is stretched you may need to count the links or re-measure the chain to ensure you get the correct length.
Where can I get the best priced chains?
If you know you are going to need a chain sometime in the future but aren’t in any hurry, you may want to try our Wiggle price alert service. Simply find the chain you want on the Wiggle website, enter the URL in our price alert page and we’ll e-mail you if the price drops within 90 days, which may snag you a bargain before you need it!