Andrew R Stewart 

Interesting vid but it has some less than right info. Steel gets stronger at the bend BUT it looses the quality of elongation. As in the steel becomes more brittle. bend a paperclip back and forth a few times and note that the bent section won't re bend as easily as the adjacent un bent section. But the clip will break at the bend anyway because that section has lost the ability to absorb the stresses of the bending attempts without cracking.

The reason why the baby jogger axle bent even though it is of thicker section than a bicycle axle is because the jogger axle is cantilevered from one end, a bicycle axle is supported at both ends. However on many rear hubs the bearings are not evenly placed along the axle so the bending forces are greater at the bearing closer to the axle's center (this bearing location allows the freewheel to fit).

While a high impact force (riding off a curb) will stress an axle so too will misaligned drop outs. So too will hitting a pot hole (a far more common incident than a curb drop off).

It's sad that learning how to figure mechanical stuff out is not taught by most schools or jobs. They do teach how to pass the test, but that is more about memorization than about the interactions and relationships between the parts in a mechanical system. As the method of repair, in a bike shop and elsewhere, has gone to replacing complete parts (like a wheel) from just replacing the offending sub part (the broken axle) the skills of threading identification has also been lost (or never learned). What's even worse (but not exactly said by the OP) is that the shop kids didn't seek help from a more informed coworker. Andy

I strongly suggest that riders don't try to shift all their weight to the front wheel when riding off a curb, unless your helmet includes facial protection (like a full face helmet or a football one)... One can pull up on the handle bars to unweight front wheel and then rock forwards to reduce the rear wheel "weight" BUT KEEPING THEIR FEET ON THE PEDALS. So some weight is on those pedals all the time. This gives the rider far more control then if there was no weight on the pedals, as in when all your weight is on the front wheel only. Andy