So a mate of mine, played homemechanic, he tells that he mounted some new pedals to hes cranks, but after 10 km riding, one pedal falled off! – so i guess he mounted the pedals the wrong way, but i read somewhere mounting the pedal from the inside could maybe restore the threads? -or should i try something else?

If it fell out it wasn’t tight enough. You can sometimes get away with threading the same pedal through the back of the crank arm which can clear the threads. However, if the pedal fell out completely it’ll probably now continue to come loose, even if he can get it to thread back on.

Worth a try though.

Worth a try and if you can clear the threads and get the pedals to fit and nip up a little then maybe some threadlock will be enough to save the day. Assuming that he won’t be changing the pedals very often.

Superstar sell a set of very well priced pedal taps