With a 9 or 10 speed chain,
you can't re-use a pin. On the older chains, a pin was pushed out until it was just held by one plate, then pressed back in on the shortened chain. But these newer chains have mushroomed ends on the pins, which break off when pushed out. Pressing in the same pin makes a very weak spot in the chain.
So either use the supplied replacement pin, or use a quick link.
With a quick link, remember that the link will replace one of the outside plates on your existing chain. Just use the chain tool to push out a pin so that both ends have an inside plate.
I really like the Wipperman
Connex links. They are extremely easy to install or remove, without tools, and are very reliable. Your local bike store should have them too. My link lasted for 2 or 3 chains before I decided to replace it. It worked great with my Campagnolo 10 speed chain.
