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Shimano XT Crank Axle Snapped

From http://ride.io/forum/index.php/topic,164818.msg1404190.html#msg1404190 as of 2013/08/10:

The poster says:

i snaped them coming out of a quater pipe at a skatepark, im not a heavy guy either im only 15 and weigh 9 stone

No report of injury.

The text has some discussion comparing "MTB" cranks, which are often used on bicycles with suspension, to "street" cranks which are often used for repeated hard landings including crash landings. That is, a crank which is durable/reliable for one use may fail quickly in some other use.

Note the left arm transition from "black" to "shiny", this may indicate the bearing had been slipping and damaged the spindle. The poster notes:

its a new bb aswell only like 3 weeks old

This raises the question why was a new BB installed? Presumably because the old one was working poorly.

It is hard to know what went wrong here, but users should be aware that parts can accumulate damage and it might not be immediately obvious but can lead to failures later on.