Yelp 99.9 % chance of bent crankshaft and sheared flywheel key. But hey what a great garden tiller or thatcher. Serious I see a riders with blades like this. I have even the spindles shafts bent on the riders. Just recently repair one deck where 1" spindle shaft was bent. This is not even from rocks but just tree roots.
Anyway if the lawn mowers are used to cut only grass and not tree roots and rocks then bar blades are not a problem. It called taking time to clear the area of hazards.
