my Cotic Soul has a BB in with crossed threads
I'm dreading the day I have to take it out!

knocked the centre of a bearing out of a ck hub once. utter disbelief at my stupidity.

Missed to locktite one rotor bolt out of the six on a fresh build. Second ride out riding down descent in Black Mtns bike starts to make an odd 'chug chug chug' noise, as I hit brakes to stop and take a look noise rapidly increases in volume and noticable knocking sensation through bars becomes very pronounced 'CHUG CHUG CHUG'.

Release front brake and come to a stop just on the back brake, awful burning smell now pervades the locailty. Royor bolt had unscrewed and neatly milled the inside of the brand new fork leg. Oops.

Luckily it hadn't taken that much material off and the forks were fine for years afterwards.

didnt pay attention riding down the road, looked over my shoulder to check traffic behind me, rode straight into the back of an mx5 and snapped the headtube off my spooky metalhead

I didn't align my valves and tyre logos once

See the "knocked off bike" thread for what happened.
Dale frame is bent on the downtube where the car hit it. But not broken!
Pace repaired the forks

Changing the shifters and mech on my brothers bike. Thought it would be faster to just cut the outers at various points so I could just pull it all apart. Got to the head tube and the first gear outer I chopped pi**es out fluid strange I thought then realised I has just cut the hose for his HS11s!

Just built my Santa Cruz Bullit after it came back with fresh paint and decals.
About to take it out for a test ride to check me gears.
Jumped down the steps at the side of my house and that horrible (exspensive) sound came from the back of the bike.
During my rebuild I had forgot to install the two pinch bolts that clamp the bearings and rear triangles axle.
Thus snapping the rear end off.
I couldn't sleep right for days, what a nob!
(Anyone got a Bullit rear triangle for sale as I still have a front end in me shed?)

OMGG this has me cracked up, in a kinda 'shouldn't laugh, but can't help it' way. Thankfully with my serious bikes (ie everything after my first GT hardtail at uni) I've taken things fairly slow and steady and not **** up TOO badly.

Not so much bike but accesories, I left my Oakley radars on the roof of my car leaving swinley, got out on the road and someone coming the opposite way pointed them out, the glasses then fell off so I swung the car round to retrieve them and ended up running over my own glasses!!

At least you caught your glasses, even if you drove over them. I lost 2 pairs of Oakleys within about 2 months in the States a few years back. The first pair I lost rafting, when I got dunked. The second pair was bought a couple of days letter for muchos dinero; lost driving out of a campsite with them on the roof of the van.
Needless to say, I managed without buying any more for a little while.

Not been that stupid with the bike. Biggest forehead slap was driving to ride and leaving the maxle skewer at home. PLENTY of non bike stupidity. fell asleep on the train last night. £30 taxi. arse.

DezB you should get that on bustedcarbon.com

Had finsihed servicing my old Z1 freerides but forgot to do the bolts up on the bottom that hold the internal gubbins in. As i pushed the lowers over the stantions the bolts shot off and i sprayed fork oil all over myself, the ceiling and most of the kitchen 🙂

Also had a beauty when shortening the hoses on my juicies, replaced the olives but not the barbs. Pulled the brakes on and both hoses shot off covering me in brake fluid!!

many years ago after bleeding the wifes xt brakes i then did my hopes but put mineral oil in by mistake, lets just say i never did that agin, doh!!

I got fed of with regreasing loose-bearing bottom brackets 'back in the day'. I fitted a grease nipple instead of the cable guide fixing screw and as it was a nice new Cannondale, I looked and discovered there were no vent holes in the bb shell so after fitting the axle and cups I proceeded to pump the finest boat trailer quality axle grease into the shell. Several minutes and a large quanity of grease later I got worried. I kept pumping the greasegun. I then noticed a 'worm' of grease coming out of the vent hole near the rear dropout. I had filled the chainstays with grease! There were 2 vents in the BB shell about 1mm in diameter through to the chainstays! Aaaargh!

Deveron53-made me chuckle 🙂

I've had plenty of little things like over tightening an ISIS BB, having the tool slip from XTR crankset left cranks bolt causing it to go round, scratching fairly new forks stanchions while checking it had the right amount of oil etc.

Looking at how much bike shops are charging for maintenance I think I'll still end up on the plus (unless I over do myself next time)…

I managed to 'undo' a pedal against the thread of a pair of Y2K XT cranks once. I was a noob and I thought it was stuck. Much swearing, puffing and sweating, plus application of bodyweight was involved over about 45 minutes before I thought 'there, thats got it'. No pal, you really haven't got it. At all.

I couldn't do it now, I'm simply not strong enough anymore.

Whilst photographing some virtually brand new forks to sell i was propping them up to take some photos when they slipped out my my hand . They hit my bench vice on the way down, badly scratching the stanchions and lowers and for some reason i paniced and tried to 'catch' them with my foot.
One pair of forks ruined and a toe nail down, needless to say it wasn't my most successful evening

Not the worst but the most recent.

I've just snapped an Allen bit in a grub screw in my new rear mech, the tension adjusting screw, cant move it in or out now, looks like i have to drill the fecker out!!!

**** it, and i thought i was being clever by replacing all the shitty philips head bolts with black allen one's on my XT stuff

As for the worst
1 new frame + cross-threading 1 new hope ceramic BB into said new frame to the point of no return (thought it was a little tight) = 1 angry (to say the least) and out of pocket MTB'er

Glad to say after some machining the frame was useable and is still around today.

trying to bend out a ding in my rear rim with a adjustable the other day. i now have a rear rim with a crack in it 😳

rounded off plenty of bolts, including the ones that are currently holding the suspension pivots together…still need to sus out how i'm gonna get them out without wrecking the frame…

Cut a steerer too short by sticking the fork into the frame, measuring, marking & cutting along the dotted line…

Note to self – ALWAYS remember to include the bloody stem in your calculations!

Measure twice, cut once. 😳

Overtightened and snapped the nut on the bottom of my Tala's!!! New Talas unit!

Like the OP I drove into a carpark forgetting all about my bike on the roof & barrier and killed my Heckler, also dented my car roof 👿 Annoying thing is the opposite end to the carpark does not have a barrier WHY???.

Anyway contacted my insurance who put me onto Wheelies Direct after sending pics then the bike, I have come out of it rather well with my dream bike a Turner DW 5 Spot! 😀

Tried to adjust the pressure in my forks whilst the bike was vertical in the shed ensuring that I lost all of the fork fluid sprayed over myself and the shed. Topped the fluid back up afterward but have been unable to get the amount right as now the travel adjust doesn't work properly.

Brand new (and rather expensive) frame, still in bubble wrap protection, upside down and back to front confusion ensued with the BB-clearing taps. Three or four turns before I realised they were in the wrong way, very surprised how little resistance there is when cutting into a steel frame.
Also bled a mate's Pace fork cartridge in a rush, and finished off fully extended rather than compressed. In front of about fifteen other riders, he took air off a speed bump and blew the top clean off, covering everything in the vicinity with fork oil.Seeing him stood there with a look of dismay on his oil soaked face, drips running off his trendy new helmet peak still has me grinning now.