Professional bike mechanics & maintenance training courses Recently I have been doing some small fixes in own bikes, I have enjoyed it a lot, then comes to my mind the idea that would be nice to help others as well, but in a more professional way.
What is the most professional training one could take to become a bicycle technician?
Since you’ve stated in a comment that you live in Austria, I think the only specialised education for bicycle mechanics in Austria is an apprenticeship: https://www.berufslexikon.at/berufe/2898-FahrradmechanikerIn/ (Austrian job encyclopaedia)
In practice I think what matters most is experience (and of course taking your time, checking things, following proper procedures etc.). An education in mechanics, engineering or even physics helps a bit for basic understanding, but in the end there is no way around experience. You could get that by either owning and maintaining a lot of bicycles, working at a bicycle shop or volunteering at free bike repair events (here in Linz there is one in a week).
A bicycle is a very simple machine but there are tons of different components and compatibility is always a problem. Having all the right tools can also be difficult.