Fixing a SRAM 11 speed GX rear shifter on my mountain bike. I was on a downhill MTB holiday and fell off, snapping the thumb trigger on my rear gear shifter.

Replacing the shifter is usually like a £30 part, but I was in an alpine resort in summer so the shops that stocked them were charging nearly £100!

I had my tools and some super glue so sat down to repair it. The snapped part fixed in two minutes but getting that part in place required the complete disassembly of the internal mechanics of the shifter which was all tensioned with multiple hidden springs, the internals literally burst apart half way through carefully taking it apart.

We had no instructions, no YouTube video (since it is usually cheap enough just to swap out) and no diagrams. It took me and a random guy staying in the chalet 3.5 hours to put it back together, we essentially had to spread everything out and think from first principles of how a shifter works, the specific features of that shifter (rapid fire, mutiple down shifts with one leave arch) and build up how those peices would match how it operates.

Must have been 30 part, all small and all tensioned with three(?) springs.

6 months later still working fine but man did we get a mental workout that day.

Next day I had to fix my 3 axis gimbal but that was a lot easier.