Entire chain cracked, out of a sudden

I got this neglected Kona Cinder Cone last year from FB Marketplace so I decided to clean the chain by soaking it in a container with WD-40 for a few hours. It cleaned up perfectly so I put it back and lubed it with synthetic lube and it worked great.

I haven’t ridden the bike for like 8 months now and as soon as I tried, the chain instantly snapped. I took a closer look and it’s pretty much disintegrated, with cracks on every single link, on both sides.

Any ideas what happened? What did I do wrong? I thought WD-40 was relatively safe to metal.

u/rainpl — 2 months ago