I am not sure it's really fair to just say bike shop mechanics aren't experts and pick up their knowledge here and there. As we all know, there is a lot of reading on the internet, and I suspect there is a lot of data that is supplied with components to shops that the general public doesn't get to see.

When you look at any sort of training, all it does is short-cut the time it takes to pick up the skills and knowledge that would gained in the course of experimenting. It's much easier and much, much faster to have someone prepare procedures or routines and give reasons why a job should be done a certain way and torques applied and preloads adjusted, than for an individual to go through all the permutations.

Plus, there is usually more than one way to do a job as wily bush mechanics will show.

Good LBS mechanics (formally trained or not) will be like good auto and aircraft mechanics -- they will keep up with their reading of manuals and technical data, and maintian their practice. Bad mechanics of any ilk will always be bad mechanics (although the resulting risks may not be so good).

You could say that it starts with engineering, but the only real difference between bikes these days in terms of technology is carbon fibre and its need to be babied compared with metal components. Engineering these days, to me, seems to be a means to find enforced obsalescene and a new fashion.

Anyway, Pete, I appreciate the discussion you have enabled. Thanks.