From 0-10 rate how bad I have fucked up. These are the fuckups I can remember from my 8-9 years of cycling:
>install the bottom bracket at an angle thus stripping the frame and making the bike unusable
>disassemble wheel hub to replace/lubricate bearings, don't know how to tighten cones properly so the wheel now has a little side-to-side play (still usable and not noticeable during riding, but it sure as shit isn't a professional installation)
>patch tube but don't inflate to proper PSI, end up getting snake bikes and having to walk/bus 20 miles back home - this fuckup took up my whole day
>spoke breaks, decide to ride on broken spoke for 2 solid weeks, more spokes break, replace only broken spokes instead of all of them, more spokes break, have to replace all of the spokes
>clean/wash chain and leave it to air dry instead of dry patting - get surface rust
>ride with old and overtensioned brake cables, cable snaps going down hill (20+ gradient) , almost swerve into traffic and die
>decide to ride 30+ miles on new and unproperly fitted seat (without hex keys to adjust seat), experience sharp groin pain throughout the ride, don't realize till after that i permanently damaged some of my perineal nerves resulting in permanent loss of sensation in the head and shaft of my penis - i used to be able to cum like 2 to 3 times in a row, very low refraction times, now after climax my dick dies 5 ever