Master link – a chain link consisting of two plates that can be mechanically connected and disconnected without a chain tool. Some links are designed for single use while others can be re-used.
Since those links allow the user to break and re-connect the chain, they are also known as master links.
How To Know If a Bike Chain Has a Master Link
1. What is the bike?
In some cases, there’s no need to look at the chain to know if it has a master unit. If the bike is brand new, it more than likely does not have a master link. That being said, if the bike is somewhat of a custom unit, someone from the bike shop might have equipped it with a master link.
The most precise way to learn if a chain has a master link is to examine it. If the chain is dirty, it’s recommended to clean it with a rag. Otherwise, the contamination will mask the differences between the regular links and the master.
It’s easier to clean the chain when the bike is fully supported. This can be accomplished via a bike stand, but if one isn’t available, you can also hang the bike from a tree branch, for example.
You can also flip the bike upside down. This position makes it easier to observe the chain thanks to the extra light and the fact that the frame is out of the way.
After securing the bike, spin the pedals and carefully observe the chain’s plates.
A master link will have larger cutouts than a standard one. (image below).
Master Link Types
Most chain producers have their own master links. That doesn’t mean, however, that there isn’t cross-compatibility between brands.
Shimano Master Links
Shimano and Campagnolo currently don’t have quick links that are officially reusable. Hence why sometimes the links come as two units in a pack.
Some people re-use Shimano links while embracing the risk. With each use, the fit of the master link becomes looser since a tiny bit of material around the slotted area is lost. In the worst-case scenario, the link will break and render the bike chainless. The failure will be sudden and may cause an unpleasant accident.
It’s also worth mentioning that some quick links have an arrow indicating the direction of the unit. The arrow should match the chain’s movement direction. Or in other words, it should point towards the back tire when the link is closer to the ground and towards the front tire when the link is higher.
The 8 and 9-speed SRAM quick links (PowerLinks) can be used more than once. However, the links designed for 10+speed chains can be weakened when re-used and are for single use only.
KMC Quick Links
KMC is another company that offers quick links. Unlike the others, however, KMC provides both reusable and non-reusable quick links for the 10+speed chains.
FAQ: What are the advantages of a quick link?
The original motivation behind the quick link was to facilitate the installation of a new chain.
Without the quick link, the user/mechanic had to use a chain tool not only to break the chain but to reconnect it too.
The second procedure was particularly difficult because the user/mechanic had to push the pin almost enough to press it out but not quite. (If the pin is fully removed, it’s close to impossible to re-install it).
Then, via the chain tool, the user would push the pin back in. Since the process would weaken the pin (metal sliding against metal), Shimano’s chains are sold with an extra pin.
The joining pin fixed the strength issue caused by re-using the old pin, but the process was still a bit cumbersome and often the connection link was stiff.
A quick link eliminates the need to use a chain tool a second time and removes the reliance on a joining pin.
Thus, even non-reusable quick links are considered valuable for their convenience.
Another use of a quick link would be chain repair in emergencies. If a chain breaks, a quick link makes the repair easier and faster. That said, it’s still necessary to carry a chain tool because you don’t know exactly which links of the chain will be damaged. In some cases, it will be necessary to remove a link to install the quick unit.
Furthermore, reusable quick links make it possible to remove the chain for cleaning without a chain breaker. In some cases, one can open the quick link without any tools (gloves will still be helpful) or via a shoelace (video below).
FAQ: What Are The Downsides Of Using a Quick Link?
Technology-wise, quick links have no notable downsides. A quality one is just as strong as the rest of the chain links.
That said, there are some shortcomings linked to the exploitation of quick links. Those would be:
- Extra tools are required for connecting and disconnecting the link (pliers)
- After a while, the quick link can become notoriously difficult to remove.