Originally Posted by
Doc_Wui
Huh. I thought master links had been phased out of bikes 40 years ago, but what do I know. I never had to open a chain until this recent derailleur swap. So that KMC chain I bought off Amazon and keep as a spare will need one? I better look.
Back in the day it wasn't possible to use any kind of master link on a derailleur bike. The ones that worked on single speeds and machinery chains would get popped going through the ders. That changed in the 80s when Sedis* came up with a new kind of link and a chain that used two less parts per link. A big deal. Those chains shifted better on derailleur bikes and pretty much took over the industry in a matter of months. The modern quick links are reliable, mostly reusable and pretty easy to work with. For ordinary people they are more reliable than the old "push the pin back in" method. I've never even seen one fail. I have had and seen failures to rejoin a chain, and those can be fairly disastrous.
Really, go with the link. Clean, easy and very reliable.
The KMC chain you bought from Amazon probably has one. They almost all do nowadays. Check the package.
* A small company in Portugal, since bought out by SRAM.