It is almost a big issue to reuse old chain pins, bike chains are new and when these are installed in the crankset and cassettes, then the lengths of these hains became smaller or larger due to which these are cut and chain links are removed from the chain by popping of chain pins, re using of these pins with the chain links is based on the brands and price ranges of chains because there are many brands of chins like shimano chains, this company do not allow you to re use their old chain pins, the reaso is that chain and chain links are manufactured by machines, and thee are not human made accessories of bikes, with the help of differnt machines and bike industries, bike chains are made by gving an appropriate and recommended length with the help of chain pins, now if you want to pop out these pins, then the holes of the left and right plates ofthe chain links would also ecome wider and the right and left ends of the pins would also screw up abdly and when you rer insert them , these wont wor accurately on any bike, as a result bike chains would again break from the exact pin place.
it is possible to re-use link pins but then your ride would remain safer no more, at any time at any place you have to face the breaking of a chain from the same damaged link pin, although you have another option, you can simply uninstall the whole chain link along with the two plates and two link pins, and insert new chain link within the chain, it is an appropriate and proper method for safe re binding and re joining of chain pins.
How To Rejoin Shimano Chains By Removing Shimano Pins?
Shimano chains have same-sized pins through which their chains are made and combined with the chain links, in the case when Shimano chains have broked from any place, you will not have a chance to reuse the same exact pin, Shimano have their special reinforces Shimano link pins which are thicker and wider than the normal chain pins, these reinforced pins are reused to combine and adjust the chain links, after reusing them, you will notice these are thicker than the other link pins, but there are other brands of bike chains which have allowed their link pins to re-use them.
Shimano 11 Speed Chain Link Pins:
The 11-speed chains of Shimano company have a big advantage, you can re-use their link pins for re-connection of the chain. I am not recommending these pins but the Shimano company has written on their website about 11-speed chains, but if you have 6,7, and 8-speed Shimano chins then, link pins of these chains are not allowed to re-use them.
Reusing Of Two Pieces Of Chain Links:
Shimano has also recommended that you can also re-use two pieces of chain links along with their plates if a single link pin has popped out remove the whole chain link and install a two-piece chain link which will increase the lifespan of the chain and make the chain durable.
Difference Between Re-Used Quick Links And Shimano Quick Links:
Quick links become old and junky, plates and pains of the older quick links are no longer used for further riding purposes, because the teeth and cogs of the chain ring and cassettes teeth would rub badly these reused quick links which the chains will break from the exact re used pin place, but Shimano new master links are fully new and these are ordered through online stores and mechanic shops, these would not cause further breaking and crack of the link plates, it is must to carry an extra and spare Shimano master link before going on road riding, hard and aggressive trails.
Difference Between Older And Newer Bike Chains:
Older chains have non-reverted pin heads but new chains have reverted heads of chain pins, older chains do not tolerate heavy loads but new modern chains are used for lifting heavier loads without any issue. pins of older chains are easily installed and uninstalled without any issue, but new modern reverted chain pins are difficult for mounting and unmounting within the chin plates. and when a new modern chain pin is removed and at the tie of re-using of the same exact pin the pin doe, not remain as durable as it was before, lifting heavier weight on the same reused pin would gain break the pin would the exact mounting and dismounting of link pin place, because it is not easier to install new modern chain pin again in the same holes of the link plates.
Mounting And Dismounting Of Link Pins:
There are different types of inserting and non-inserting of pin links, if the pin is totally coming out from the holes from both of its sides, then it is totally removable and cannot be used further. but if the pin has dismounted from one side of the chain plate then there is a 50% chance you can reuse these pins further for combining chain links with each other.
Which Is Better Quick Link Or Link Pin?
If your chain has been broken and you are looking to rejoin and re-combine the chain, then never use chain pins because these are not much more durable than master quick links. always buy Shimano or park tool quick links for safe riding.