Started ride with perfectly straight disc.

Caliper doesn’t rub, I’m not a serial brake dragger.

Returned with disc shaped like a pringle.

Any ideas, stw hive mind?

Heat can warp stuff. Dragging brake causes friction. Friction creates heat.

Did you stop at the pub?

You crashed?
You caught it on a tree stump whilst negotiating a tight left hand bend?
Got a tree caught in it?
Pixies?

rock strike? I managed to pringle a rotor on rangers path, didn’t notice it til we stopped and rear wheel was very draggy, caused a fair bit of brake pump on the second half 😳

I’ve also managed to break a couple of bashrings (admittedly weedy plastic shimano jobs) without noticing how/when I did it.

No crashes. Don’t remember any tree stumps. But good thinking.

And Good call on rock strike, there were plenty of rocks on the way back down. Mystery solved (perhaps)!