Have you ever...

done something/had something happen to your gear that made you retire it without the reason being visually evident?

I've retired a couple of biners, a few nuts, 4 ropes, and had to do some trigger repair, but the reasons have been very evident. I've also worked in multiple institutions and retired things there liberally. All the damage was evident.

I just want to know how often an invisible "time bomb" is created.

This is in response to a bit of discussion on the safety of buying used gear. There are as many opinions on this as there are climbers, but it seems to be that most people fall into one of three categories: no used gear ever, only hard gear, anything as long as it looks good.

Where do you fall?

Evan

Dropped carabiner or quickdraw from 15' to rock a couple of times, retired. No visual evidence of damage. I black tape them and use them for other things (carrying lots of nuts, or leavers but always 2). Likewise if I find a carabiner I will only use it for the same. But if I find a cam or nut, that's different. I use it like it was new. I won't buy used carabiners or ropes but will buy used cams.

Also, rope gets retired after 5 years but I'm not one to hammer my rope and I don't climb a ton.

Retired a couple partners....

I'll pretty much buy anything used as long as it looks good, other than a rope. I'd prefer to buy that new so that I know its history. But to be more specific, if buying things online, I probably wouldn't buy soft goods. Anything else is fine. Microfractures are a myth, get over it.

i don't know about climbing helmets, never worn one, but i retire ski helmets after a big hit or two, if i get a concussion, that one's done even if its still intact.