Quite often all the development testing is great, and the the vehicle goes into production, maybe alternate suppliers are used for some component, purchasing decides on a lower cost part, the production personnel actually start building it at manufacturing rates, and a lot can change.
I agree with pffog. And the more complex the product, the more opportunity for issues. Producing any vehicle from concept to production is quite a task in itself. Unless you've been in engineering, manufacturing, purchasing, test/development, production, etc; for something as complex as a self powered vehicle you really don't fully understand the multitude of possible issues. Yes we expect a lot from our highly capable bikes right out of the crate, but humans are involved too.
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