MikeWMass

Good judgement comes from experience..
Experience comes from bad judgement.

ctpres

Dumbest is the one I did not do. Left seat angle the same on my Zenetto for over five years. Now metal clamshells are frozen in carbon fiber seatpost.

nmichell

I decided to move into the modern world this past summer and got a new wheel with a PowerTap hub. I figured I'd also change the gearing, so I got a new cassette, chains and chainrings. You have to know that the most I'd done up to this time was change a flat and true a wheel, so this was all new territory for me. In addition to the mistake Jppe cited in the original post, I also failed to realize that the middle chainring on a triple is different from the small chairing on a double (hey, they're the same # of teeth!). And I think I had a chainring on backwards. And I failed to get the crank set all the way back in properly. And maybe a few other things -- the very friendly bike mechanic at the local shop made a list for me so that I wouldn't make the same mistakes again :-) Not too expensive a lesson, and I'm sure I'll try again one of these days.

Doc_Wui

Forgot about that one. I replaced a steel fatbike wheel with an alloy wheel with all those cool holes in it . Pumping up the tire, the tube pushed out of the thirty six 3/4" holes like cousin Daisy filled out her shirts on Dukes of Hazzard. I was inside my house when I heard the kablam.

Being car guys, the Dukes would have known about PVC rim strips, but they were new to me. Well, I bought one, The rip in the tube was a starburst pattern, 3/4" across, and that was how I was able to patch it first from the inside of the tube, and then a second patch outside,

Xyrium

It's tough when you install stuff while the bike is upside down, eh? That's excellent though, thanks for posting.

Last ride 76 

Haven't done this one (yet), but remounting cranks so they are both down at the same time.... It was funny briefly, but it really makes climbing hills HARD.

GerryinHouston

Guilty of the Original Sin (OP's). Passed the chain over rather than under the tab.

The only reason it qualifies for the 'dumbest', is that I'd done it the last 3 times I changed the chain. Twice on my bike and once in my wife's bike. ...and it is not that I forgot!... I checked the tab on the lower jockey pulley when I installed the chain (just about geometrically impossible in my bike, but it happened in my wife's bike!...). Took five minutes to fix... wife is still smirking!... (she told me, 'didn't you have this problem in my bike?'...).

rydabent

When I was about 12 I took my New Departure coaster brake apart. I cleaned it all up and put all the discs with ears in first and then all the round ones in. NO brakes. Took all apart and put in all the round ones the the ones with ears. NO BRAKES. Took apart again and alternated the discs. YES BRAKES. And about that time Dad got home. Was I ever releaved, since Dad would not have been pleased I was messing with my bike.

rlmalisz

Not a serious mistake, but probably a dubious choice in hindsight. My second bike (PR10) paint started getting fairly beaten up after a couple years of hard commuting. So I took it apart, took to a local plating shop, explained that any openings had to be plugged during the process, and had them strip and nickel-plate the frame and fork. I never had issues with the finish after that...nickel will tarnish a bit, but it held up quite well and still looked crazy-cool when I gave away the bike 5 years later.

The shop guy here in Portland I donated it to smiled, and asked why I hadn't had it dime-plated.

--Richard

Iride01 

Old thread but topic should be timeless.

Very recently I tried to put some braze on cable stops and bottle bosses on my Raleigh Competition. Admittedly I'm not a welder, brazer or solderer. But I've always managed to make it look good enough for other things.

Being very low on both O2 and acetylene I rushed too much. It looks crappy. A bottle boss doesn't line up quite right. I didn't even get the down tube stops on good before I ran out of acetylene. Not wanting to spend several hundred to get my bottles refilled as this will probably be the last time I'd ever want to use them. Don't think propane or MAP gas torch will get the job done.

Sadly my Raleigh might be toast unless I can find someone to fix it for me.

deacon mark

I was riding in an organized century trying actually for a decent time since that is my only form of racing. I had some issues with shifting of the rear derailleur and noisy jumping gears. I keep working the barrel adjust the whole ride hoping to find the sweet spot did not want to stop and take time to dial it in. Never could get it dialed in and wonder why but then I finished got home and realized the whole time I was simply adjusting the front derailleur never the rear. Yes I did know the difference before hand but too intense on time and pace to get me to think it through?

Riveting

My opinion of a "dumb" mistake, is one that you could have easily avoided. During a flat repair last weekend, I swapped out a tube without positively finding the root cause of the leak, which, of course, caused the new tube to get the same puncture/leak. What makes it my "dumbest" mistake is that I knew better, yet I did it anyway, due to frustration and haste.

friday1970

To fit a rear larger tire, I took the wheel adjuster screws out of my 1987 Trek 330's dropouts. The wheel did fit, but this put the wheel spokes close to the bottom sprocket of my RD. Too close actually. I shifted up to my largest cog while still on my large chainring, and into the spokes goes my RD. The RD pulled the spoke right through my wheel, damaging the it beyond replacement. I had to do a call of shame to get home.

This was the day before a 200k brevet, and I had to scramble to buy a new wheel for the event. $120 mistake.

cheesesandwich

Not a repair. I bought this round rubber thing meant to replace the stickers at the end of the bartape. Its a small whole round piece so removing the shifters is necessary. I thought I'd do it when the time comes to replace the cables too. So after removing the old bartapes and shifters I thought I was smart enough to put the rubber first, then when the bartapes are done the rubber will go over them. But what I should have done too is to put the cable housings underneath the rubber. After all was done I realized the housing was over and it stopped me from getting the rubber over the bartape. I can't remove it like a normal sticker, everything needs to be undone and redo again. I end up using the bartape stickers and the rubber lay useless on the handlebar. It will take a year or so for another round of cable replacement before I can do it right.

Biker395 

Let's see. There are soooo many.

#1 I took apart my rear derailleur to clean out the idler pulleys. I didn't have a torque wrench at the time, but I thought I tightened the bolts more than enough to hold it together.

So I was riding home on it later that afternoon. The shifting got a little squirrelly (it had downtube friction shifting), and POW ... no shifting and no pedal resistance.

I braked to a stop, and watched both little idler pulleys spinning off in front of me and down into the creek.

#2 Installed new cleats on my shoes. Again, did not have a torque wrench, but I thought I tightened them enough without overdoing it.

On my maiden voyage, came up to a 10% hill with a stop sign at the top. I stopped and went to unclip, only to discover that no ... I had not tightened the cleats enough. The simply spun in place. As I rolled backwards and downhill, being a skier, I instinctively tried to put myself perpendicular to the slope. All that did was swing me around and slam me to the pavement on the downhill side. I had to take OFF my shoes to extricate myself.

So yea ... I have a torque wrench now.

zacster

I just replaced my cassette and I tightened it too much so that when I was coasting downhill it wasn't freewheeling and the chain was slapping the stay.

GlennR

Over torqued the crank fixing bolt. Must of set the torque wrench to the Nm setting but in ft-lbs.

Left crank arm came off. Luckily I was in the saddle and close to home.

Wanderer

Soooooo, just turn the wheel around, and you are good to go!

GeorgeBaby

​​​​​​​As soon as I saw the title, I knew I'd have to admit to the same. I do this, but now immediately spot it, at least.

John_V 

Besides the incorrect chain threading, which I think all of us has done at least once, my dumbest oopsy involved my cassette. I clean my cassette by removing it and bushing each cog with a hard brush and degreaser. This particular day, while taking my time, the wife came out and reminded me that we had to be somewhere soon. Crap! Quickly brushed the rest of the cogs and put them back on the wheel, mounted the wheel and cleaned up the work area. Next day, I'm riding and shift gears and besides the noise it made, it became much harder to pedal. Pulled over and checked the cassette and realized that in my haste to get the cassette back on the bike, I had placed a cog in the wrong order; small cog between two larger cogs. Good thing I was on a solo ride. It would have been pretty embarrassing has someone else been with me.

grizzly907la

I've started working on bicycles and so far the worst mistake I made was using the wrong crank puller to get pop off a crank. I stripped the threads, and I had to resort to cutting off the cranks with an angle grinder. It was brutal!


The wrong crank puller.

The chainring after doing some cutting

The remains of the day!

curbtender

Grizzly, right...

grizzly907la

????

curbtender

Little tease, glad you are not a doctor, lol. Or are you?

grizzly907la

LOL. I'm not a doctor, but I know the stuff they do can get a little grizzly (no pun intended,) sometimes. though I did feel like a civil war doctor when I amputated that crankset.