A riders rear wheel was replaced by the bike mechanic but not properly in the drop outs even though it tight.
The rider didn't notice until we rode up hill and his rear freehub was slipping so we thought and the chain went straight into his spokes snapping 2 of them.
Checking his mech I pointed out his rear wheel was not in the dropouts properly as he fiddled with his mech. Quick release adjustment and bike was running fine again except for broken spokes-sorted by another LBS round the corner.
Talking to the pal today, he's miffed and blaming the mechanic who put a new quick release in for him but probably used a stand with the bike in the air.
I told him he should check his bike for safety before any ride which annoyed him (Sorry T!)
I reckon it was 10% mechanic and 90% bike user not checking bike before an epic 50 mile ride I organised!
Who's to blame?
(Ok I might be a bit harsh on him? but I check my bike the day before!)