KMC quick link woes
 

I used to swear by these. I like them so much that I have a ton of spares. But on today's ride, the quick links somehow disengaged by themselves. When i put them back together, they came apart again under load. So now, there's a new quick link on there.

Any ideas as to how this could have happened?

Could it be that you installed them wrongly the last time u cleaned/installed your chain? I have been using those with my stockpile of Shimano 7800 Dura-Ace and KMC 10-Speed chains for a long time without issues. After installing, you are supposed to apply your brakes and step on the pedals to lock the link in place.

Another thing I do is toss the link with my old chain. I do not re-use the links. I had bought two cards from a store on E-bay.

you keep saying links and they? how many are you using?

ive never had one that came loose during a ride though. the last kmc chain i got (X10SL) i could barely get it to lock shut. i havent even attempted to get it to unlock. i doubt i could with out quick link pliars. all the other kmc chains i have used i have been able to open and close them by hand and they never came unlocked either.

i would guess it wasnt fully locked when you started the ride. it just doesnt seem possible for it to come off when ridding

dont reuse them

thanks for the response. I'll chalk it up to a fluke for now. The pair of links were new. They were fully engaged and have been working for the last 1000 miles. i now wonder if something else mechanically forced them apart (say a bad shift).

Under load is when they are supposed to be their strongest. It must have had a defect.

Maybe your chain is too long, or a derailleur is just dirty and it doesn't move so well.