jppe

CliffordK

I did that once. Older Ultegra 6500 derailleur. Rode a century and a half ride. The chain was noisy, so I added lots of oil. Then discovered the real problem the next day. Had almost worn that tab in half.

Barrettscv 

I've done that more than once. I usually figure it out just after I've completed the final assembly. I then have to break the chain, reroute the chain through the derailleur arm and recheck the chain length.

My dumbest mistake involves a bad plan and even worse workmanship. I wanted a vintage steel bike that would fit 700x32 tires. I had a 1979 Trek that easily would fit a 32 tire on the front, but not on the back. So I took the bike to an experienced frame builder and requested that they oval-ize the chainstays to give me an additional 3mm of room for a bigger tire. Well, it was mission impossible from the beginning and the chainstays looked terrible and the rear triangle was probably no longer true. I moved on to a 1971 Peugeot PX10 which easily fits a 700x32.

MikeWMass

Back in the day, the first time I had to break the chain on my first 10 speed, I pushed the pin all the way out, then could not get it back in. Brought it to the bike shop for help, left with a new chain.

ridelikeaturtle

LOL this is one of those things that I've done and now (and forever) will check and re-check before reconnecting the chain.

Have you seen my "misaligned head tube badge" thread? That's my latest, though it's pretty straight now.

I once threaded drop bars through a quill stem backwards, after I took way too long trying to make sure I didn't do exactly what I'd just done. Wow was I annoyed with myself.

KenCT

Geekage

Would falling for the Sunk Cost Fallacy qualify as a mistake?

I got a similar vintage PX10 from my great uncle by way of my dad, then my eldest sister.

First I replaced the tires with something more puncture resistant (Wolber Invulnerable tubulars). Then the rear derailleur- I was somehow able to find a Simplex rear derailleur, the kind that's unthreaded but uses a bolt through the back to hold it on, because that's what kind of dropouts the Peugeot has. Then a new freewheel or three. Then a new rear wheel (after bunnyhopping straight onto a speedbump)- clincher! Maybe the wheel was before the freewheels- I can't believe the Maillard Atom freewheel wasn't also some obscure French threading. Then the chainrings- some shop was able to find me a 38 tooth inner ring in the Stronglight bolt circle diameter to replace the stock 45 tooth, then pedals after retapping the crankarms for current standard threads instead of French threading. Then sidepull brakes (Suntour Superbe- not Superbe Pro, those weren't available in long reach) to replace the old Mafac Racer centerpulls, bars and stem (again, lucky to find something that fit the narrower French steerer tube and the Cinelli bars). Maybe a new front wheel about this time. Scott Mathauser finned brake pads. Campy headset. Another wheelset that I handbuilt. A new rear derailleur after tapping and filing the dropout. Indexed shifting- brifters, rear derailleur, freewheel. New saddle after the Brooks kept creaking so much. Seatpost for some reason. Etcetera.

Obviously, all that was way more than the $550 that I spent on a used bike which replaced that Peugeot eight(?) years ago.

Okay, maybe it wasn't a single repair mistake, but instead a series of them digging me into a hole until I finally got frustrated with trying to find vintage French parts or trying to modify the bike to use more modern parts.

big john

I've messed up threading the chain through the rear derailleur before but caught it before leaving on a ride. I helped a friend who broke his chain on the side of the road and I missed threading the front derailleur. I had so much trouble joining the chain with my multi-tool I decided to take the derailleur apart instead of breaking the chain again.
I've been known to leave chains on my bikes long after they should be replaced. One time I was way up in the mountains and I heard a lot of clicking from the chain but I didn't want to stop and check it out. By dumb luck I made it home to discover one of the pins had come out of one side and the plate was just hanging there.

Barrettscv 

Your "failures" read like my success stories!

canklecat

Dunnit too -- misthreading a chain. One reason I've used quick links on bikes since the 1970s. Quick and easy to fix.

My dumbest stunt was in the 1970s or early '80s. I decided to experiment with using oil rather than grease on hubs, thinking it would reduce resistance to spinning -- just before a 75 mile ride. All I had around was WD-40. Never occurred to me how it would affect cooling. During that ride I drafted a truck and reportedly got up to 50 mph. Later I wondered whether I'd cooked the hubs but they seemed okay. I switched back to Phil grease, pronto.

More recently, last year, I "fixed" a front derailleur adjustment that didn't need fixing. It worked fine when I bought it from a guy who flips bikes for a living and does a good job of making sure the bikes are safe to ride -- properly adjusted, new tires, cables, brake pads, etc., if needed.

But when I looked down from the saddle the front derailleur looked a bit askew. So I "fixed" it by setting the outer plate parallel with the outer chainring.

Big mistake.

That front derailleur relied on some clever little nubs between the plates to nudge the chain while minimizing chain rub even with cross chaining. The conventional wisdom for visually aligning the RD outer plate with the chainring thwarted the manufacturer's design. For months I kept experiencing chain drops at the most inconvenient times -- like, hill climbs or just before a group ride began a sprint.

I finally caught my mistake when I installed a new ramped and pinned big chain ring and took off the front derailleur for cleaning -- I studied the design and realized why it was made with those little nubs inside the plates. Reinstalling it slightly askew fixed the chain drop problem. There's a slight chain rub but I've left it alone. Reminds me to not "fix" the work of a more experienced mechanic. They usually have reasons for what they do.

Hondo Gravel

Wildwood 

TiHabanero

30+ years ago in a hurry I crushed a seat tube on a road bike. That was the dumbest, but the most frustrating was cutting the wire on a bike computer when cutting a zip tie that held the wire to the frame.

John E

As a grad student in the early 1970s, I worked at the Bikecology bike shop chain in Los Angeles. The main errors made by the mechanics were allowing PX-10s to slide down in the shop stand, invariably obliterating the Reynolds 531 decal. (I am guessing that is what happened to my Sieger, which bears a San Diego bike license decal right where the 531 decal should be. ) There were lots of "pings" from over-torqued bolts, and one guy who pretzeled a rim while trying to true it during a job interview.

I made the mistake of being an early adopter of radial spoke lacing of the front wheel, not realizing that older hubs were not strong enough for this. Several broken spokes and one broken hub flange later, I reverted to 3-cross, with an occasional 2X 32-spoke build. I also saw a neighborhood with a completely radially laced rear hub. I do not even want to think about the number of chainstays I have seen crushed by kickstand clamps.

leob1

I've done the chain over the dumb little tab too. On my wife's bike. I thought it was just the usual noise from the shimano chain. oops.
I also trued one of her wheels before a race, and I had to move the reflector(she insists that they stay on the wheel) by sliding it toward the center of the wheel. Trued the wheel, back on the bike ready to go. After her race, she tells me her reflector "exploded"! What happened is that I either didn't move it all the way back or did get it positioned right, and as she was hammering a long it twisted sideways, and bridged the chainstays. POW, that was the end of that reflector. So then of course my sense of balance would not allow me to have one on the front but not the back...

tcs

I have storage tubs of parts from 50 years of tinkering with bikes. So I ordered a new bare frame. It wasn't expensive, just a little Chinese built chromo number w/o decals. I got it, unpacked it, threw the big box into recycling, put the frame in the work stand and started building. It went together great and was shaping up to be a schweet little ride. As I put the torque wrench on the final few parts, I was really getting stoked at the 'birth of a bike'. I was wrapping the bars when I noticed they'd sent me the wrong size frame...

TakingMyTime

Throwing away used parts that I thought I'd never have a use for. This has been a rather expensive mistake (several times). I never learn.

2cam16

A few years ago I was overexcited to get a bike build going. Was in the process of pulling the driveside crank off. I was wondering why all of a sudden my crank puller came off while I was wrenching on it. Turns out I forgot to unscrew the bb nut. Stripped the threads and cost me cutting off the crank. Good thing I had a spare set!

indyfabz

Taking my bike to a certain LBS that shall remain nameless. The placed messed up several things.

fietsbob

I now regret not painting the threadless fork steerer or greasing it,
because now the rust on the outside of the fork steerer, has made me face cutting the spacers (Plastic Cane Creek Interlocking)

..in order to potentially , service the bearings..


I did have a small collection of C&V parts in a box , at a shop, my co worker threw away, in 1989.. <did not make me pleased>


OTOH .. nice Recovery .. I over tightened an 8mm bolt threaded into aluminum, on the Yoke on my new Trekking bars ( in 08 )..

And found I could run a solid front hub axle all the way through it and fix it with the axle nuts on the ends, ,

and as such it was more solid and reliable that the original piece ... ... keep thinking of beautifying it with Acorn nuts ..

haven't bothered, yet..








.../

dicktill

I once threaded an Ultegra 6503 front derailleur cable wrong (at the derailleur), and wondered why it didn't shift well, although I rode it that way for hundreds of miles. : (

Riveting

Red Loctite

Riveting

Dumbest "auto" repair was pouring a bottle of ATF in the gas tank thinking it was gas treatment. Both bottles were on the same shelf in the shed, and were in the "exact" same shape bottle. I swore like a sailor for 20 minutes thinking the car had to be towed to the mechanic, gas tank had to be dropped and flushed, or possibly replaced, then I Googled it and realized some people actually do this on purpose, and all I had to do was fill the tank (to dillute it as much as possible) then drive normally. Who knew?

JohnnyCyclist

Bought an aero frame on fleaBay. It takes a round seat post but has a teardrop shape at the top of the seat tube. The seat post is loosened/tightened by lifting a rubber cover and accessing a bolt hidden inside the rear of the seat tube.

Seller sends a message saying "be careful with the seat post attachment - it fell down the seat tube after I removed the seat post and I had to shake it back out". When I received the bike, I found a separate padded envelope with the same warning written on it and the seat post attachment inside.

Here's where the stupidity starts: I'm looking at the part and thinking "huh? how is this supposed to hold the seat post in place?". Ok, on to trial-and-error. First try: down the seat tube it goes, I shake it back out. Repeat for the 2nd try. I'm scratching my head, thinking "something's wrong here", but keep trying. On the 3rd try, the piece gets stuck, I give the frame some serious shaking, and a totally different piece falls out!

I now realize there are two pieces to the seat post attachment, and one was stuck in the frame the entire time (I'm not going to point-the-finger at the seller - I was equally stupid). After some more shaking, the original piece comes out of the frame, I now have both pieces, and my next seat post installation attempt is successful.

As it turned out, I 'got lucky'. I knew something was wrong from the start, but if the second piece didn't fall out of the frame on its own, it would have been very difficult to figure out. There was never any rattling noise - I had no idea it was there.

Since then, I haven't removed the seat post on that bicycle, but if I ever do, I'll turn the bike upside-down

bonsai80

Was removing a Shimano 600 non-drive-side crank arm from my Nishiki Tri-A so I could service the bottom bracket. Removed the crank bolt, threaded in the crank remover tool, put a wrench on it, gave it a good pull... and nothing, wow that old crank was really on tight. So I gave it a really, really good pull (because if a little force is good, then a lot of force must be better),... hey I think it's moving now... and stripped out all the threads in the crank arm. Turns out there was a washer still inside that was blocking the crank tool from pushing on the tip of the spindle.

I practiced saying impolite words as I cut the crank arm off with a dremel cutoff wheel. Ironically, I was able to find a complete 600 crankset for $25, and after fixing the bike, later sold the leftover drive side arm for $35 so I netted 10 bucks from the fiasco.