before i knew anything about bikes, i would grease everything up with cooking oil.... no, not motor oil... COOKING oil! (I was a college student and cooking oil was the closest thing we had to lubricant in our apt). I gunked up the chain, and ruined my noisy rear hub, and had to pay $60 some dollars to get it replaced with inferior components

I was not careful enough and let the wrench slip on my black Stronglight Paramount logo headset nut and scarred it through the black. Try to find another one fo those! Stupidest thing I have ever done, bike-wise.

I just put on new grips,but the lettering is upside down. Big deal.

Putting my chain back on - realising I didn't thread it right - starting all over again.

Trying to stretch a new cable with a set of heavy duty pliers instead of a real cable stretcher. The pliers slipped off of the cable and hit me in the chin. I earned a trip to the ER and two stitches for that one. Fortunately I was in the Air Force at the time so it didn't cost me anything to get the stitches.

Zack

I didn't really know how to use a crank puller last year, but I had one and thought I would give it a try. I stuck it in there, spun it around, nothing was happening. I pulled out the crank puller and all the threads on my crank came with it, D'oh! The LBS now takes my cranks off for me.

-Middi-zon

The first year I commuted, I would apply Vaseline on the chain when it would squeek too loud. I also wrapped my cable lock around my downtube shifter to keep the derailer in gear (instead of tightening the D-ring). When I had a flat, I called a cab.

A couple of years later I misthreaded my crank extractor and stripped the threads of the crank.

Forgetting to reconnect the noodle after replacing the brake blocks... :blush:

..... you too eh? a fist full of nothing!!

Me too, except with me its after punctures.

OK who hasn't done this?

While on my learning project of fixing up a junker, I liberally coated all the cables with bicycle grease. (Not cooking oil, but bad enough! ) anyone know a quick way to clean it up, or do I have to take everything apart again and wash it before oiling? Sticky brakes, sticky shifters....

Well, it was meant to be a learning project, and I learned something. (For one thing, I intend to let my LBS do all necessary repairs on my GOOD bike!)

Ditto!

I was overhauling my headset, and i didn't took out the computer, guess, accidentally cut the wire of the bike computer... good think they sell the same thing at Mountain Coop., I didn't have to buy the whole set

Cleaning my cogset with solvent, the solvent went right into the freehub; very smart move........

did that once.... rememberd to connect the front brake... but forgot about the back

as they say... the rest is history!

Finding out on mile 91 of a century what happens when you don't rotate your tires and put 2700 miles on the back one...

First time I replaced cables on my road bike that has STI shifters i didn;t make sure that the shifter was set at the lowest gear.

After installing the cable and trying to shift the darn thing it didn't shift well.

Brought it to the LBS and he told me what i had did, showed me the right way and $150 CAN later I had a new STI shifter.

DOH!

Digger

Many years ago: Repaired a tubular tire with dental floss when I didn't know what kind of thread to use, and repacked some hubs with Vaseline--surprisingly, both worked for a while!

Filling up my rear wheel at a gas station and watching in horror as the tire exploded like a shot gun!

As a young cyclist (about 15) with a single speed CCM, I did all my own repairs. I can't remember why I took it off, but I couldn't get the handlebar stem bolt back in, so left it out. Everything was ok for a couple of days until I tried a little front wheel lift while crossing the railway tracks. The handlebars came off in my hands and the bike did a slow arc to the right before crashing into a bullding. Luckily, no major damage or injury!

I destroyed a crankarm once by forgetting to remove the flat washer before screwing in the crank puller. I couldn't figure out why it was so hard to turn. My response was to crank harder. To my chagrin, the threads were sheared in the process. Do not try this at home. Gino

Another stupid thing I did was replacing a Shimano chain pin in the same hole from which it was removed. (I now know you need the special tapered pin to prevent the chain from coming apart on a long ride, which is what happened. in the process, the chain whipped in an upward fashion from the rear cluster and made a nice series of gouges in my right chainstay. Luckily, I had a piece of wire with me to connect the chain for the long ride home. The ride consisted of short 1/2 pedal stokes since the wire I used to connect the links wouldn't fit through the rear derailleur. I got a million of 'em. Gino

The same here

Forgot to tighten up my back wheel fully after a rebuild.

Didn't notice until I cornered then out of the saddle pushing hard, pulled the backwheel into the chainstay, locked up, skidded, hit the kerb, hit the family jewels on the top tube and gathered various other bits of gravel rash.

I have always remembered since.

Put the wrong size bearing cone into a hub once (mistake was by my LBS in selling it to me, tho...). About 5 miles into my ride, a bearing managed to get out of the race, knock off the cap, and the whole hub fell apart, bearings all over the trail. I walked 2 miles in road shoes with Look cleats (and no cleat cover...) with my bike over my shoulder. Called a cab to get home.