bargainguy

When I went to bike school a decade ago, we had three different bikes to practice rebuilding skills: a Lemond Tourmalet road bike, a Trek 6500 MTB, and a Trek Mystic kid's bike. Trek had donated 10 of each to the school so that students would have something current to wrench on.

Those bikes had been built and rebuilt dozens of times by previous students, and were approaching the end of their rebuild life. Even though the bikes had never seen pavement (no one was allowed to ride these bikes, they were student practice only), they were on their last legs, with threads getting pretty iffy.

Curious if any of you have worn out a frame by rebuilding it too many times, and what bearing surface finally did it in.

cbrstar

I think you have a unique experience there. Personally I've owned a few bikes where the previous owner had no business trying to use a wrench on it, but that's more incompetence then wearing it out.

Kapusta

Sounds to me like you may be a leading expert in this. I can't imagine any other scenario where a bike would be rebuilt dozens of times, let alone be witnessed by someone who knows it is happening.

Andrew R Stewart 

Well if you are good at what you do then rebuilding a bike can, with maybe a couple of exceptions, be done dozens of times. The possible exceptions are a tapered square crank arm slowly opening up and the arm drawing further up the taper till... Other press fits also loosening up (headset cups and crown race, cartridge bearing housings, cotter pins. I exempt wear items like cables and bar tape as we all know they are consumables. Unless the fasteners are heavily handed the threads should last for very long even with repeated rebuildings. Andy

bargainguy

Whoa. That's a scary thought.

A marginally related story from 35 years ago, when I was in my mid-20's. I was taking part in a fairly low-budget week-long bike trip sponsored by a local newspaper, going from one end of the state to the other and sleeping on gym floors or camping out.

On this trip was a young man, maybe seventeen, I think he was still in high school. Kinda quiet and stayed to himself. But every night after dinner, he'd set to work. He'd unroll a blanket and a full tool kit, and completely disassemble every bearing surface on his Bianchi road bike. Like any good mechanic, he'd thoroughly clean every bearing and race, pack it full of fresh grease and put it all back together again. Generally took a couple hours, sometimes more if he went really slow, like he was stretching it out.

First night, I thought it was quaint. Second night, I went up to him.

"Does your bike need a rebuild after the one you gave it last night?"

"Not really."

"Then why are you rebuilding it again?"

"Nothin' better to do."

I wonder if that Bianchi ever met the end of its rebuild cycle just like the student bikes.

veganbikes

I have not worn one out yet but I can see it happening especially as you were describing. Pulling things apart once a year probably won't be so bad but over time it must take a toll. If you are doing it more often and using them as a teaching tool then you will certainly wear things out faster because inevitably you will have someone buggering the threads in some way or if you are tapping each time then that will certainly take away a little each time.

Rebuilding a bike each night is a little extreme but then again the Pro mechanics are usually doing that but then again the pros can get new bikes next year and have spares, that Bianchi kid probably didn't have a bunch of spares on a team car or bus or warehouse.

Stev8del8

The answer to the ultimate question in the universe is 42.

Oh, and thanks for all the fish.

Jeff Wills

I think if you tighten threaded bottom bracket cups enough times you'll eventually wear the threads to the point they would strip. I'm thinking steel cups in an aluminum frame. It would take a lot of repetitions to do this.

Andrew R Stewart 

Jeff- You're correct but the question is that classic balance issue. How tight how many times with what situation. Lots of variables to hash through. The BB and the headset use fairly fine threads for their diameters so that the amount of overlap between frame and component are fairly minimal. Stripped threads on a fork (even steel) and a shell are not unheard of in the least. But in the normal world (not a school with no real use of said bike) thread damage is almost always from poor assembly or lack of maintenance, assuming when new there wasn't any out of spec dimensions at the start.

This question is interesting but I feel it's a bit moot. Since these bikes (donated by Trek to the school) were never to be ridden their acceptability is based more on their continued ability to be dissembled and reassembled without failures of fastener/thread retention.

Kind of like how long before is a wrench no longer useable. It depends. If any one of the class/practice sessions had a student go too far in their torqueing of some fitting then it might strip out/fail right then. But the other student 's bike might last many dozens of classes more.

Open ended questions re fun, to a point. Andy (who has reached his point now)

AnkleWork

Turn the equation around. The limiting factor is how much wear the bike gets from riding between "rebuilds." Some posters here apparently are at risk of wearing out their bike by working on it.

CliffordK

I think many components could show wear. Perhaps less for some mechanics than others, but for example, I've rounded a few spoke nipples in my life. Ok, so a 10 cent piece, just remove it and reinstall.

Occasionally one will gall threads. Probably less so if one is careful to lube them?

I hate those old Regida 2 prong freewheels. Even with the greatest care, eventually they'll get the slots rounded, especially if one gets it mashed on good and tight.

I would think there would be issues with some tools, so as both parts and tools wear,the tools may eventually get to a point where they will no longer hold the worn parts.

LesterOfPuppets

Seems like the Tourmalet should last longer than the 6500, since it's got steel BB shell and headtube vs aluminum on the 6500

LesterOfPuppets

Unless the school also bought a bunch of sacrificial aluminum HS cones(or cups) and lockrings

Gresp15C

Consider that every student got to learn what "crossed threads" are, on the same threads.

LesterOfPuppets

Yeah, the threads on those MTB BB would go pretty quickly I'd think.

Seems like road shifter bar clamp bolts would be high in the list for first bolt head to get stripped, since they're tough to get a feel for. Then cable anchor bolts can need to be used a couple or more times in a build.

I'd guess they have bins of replacement hardware for stuff like that, however.

Koyote

And then there's the philosophical question: how many parts can be replaced before it becomes a different bike? I have a LeMond Tourmalet, and when someone asks "How old is it?", I respond that it's fifteen years old, but the crankset has been replaced twice, wheels thrice, RD once, saddle twice, etc.

It's like the old joke about the woodsman who brags about having the same ax for twenty years: "I've only replaced the head twice, and the handle three times."

fietsbob

OP asks a question, he may have to keep count in his situation and report back..

how many did it take.. ??

daoswald

What does rebuilding a bike even mean?

To me there is one component that represents a single bike; the frame. All of the components around the frame can be replaced, and it's still the same bike. When the components fail to the point that they're no longer serviceable they get replaced. So if the frame is still viable, the bike is still viable for rebuilding. What parts of a frame are likely to wear with repeated rebuilds? The bottom bracket, the drop-outs, the head tube, the brake braze-ons or threaded mount points, and rack braze-ons. As long as those are viable it should be fine for rebuild.

But on the other hand, let's say I have all of my components in excellent shape, but dent the frame beyond repair, or crack a carbon frame. So I purchase a new frame and mount all my existing hardware on this new frame. Have I created a new bike, or have I just upgraded one component -- the frame?

A bike can be rebuilt forever. Every component can be upgraded, including the frame.

This is a similar situation with computers. I bought a computer in the early 90s with a 5.25" floppy drive, 3.5" floppy, 1MB RAM, 80286 motherboard and CPU, Olivetti keyboard, CRT monitor, gray desktop form factor case, and a 100MB hard drive. Eventually I added more memory, then a larger hard drive, then swapped the case to accommodate full-length ISA cards, then swapped the motherboard and processor to a 386, and later to a 486... added cards, upgraded the case, added memory, upgraded the hard drive, added a zip drive, abandoned the 5.25" floppy drive, added a tape backup, swapped out the motherboard to a Pentium level, upgraded some cards, upgraded to a tower case, and so on. The computer I have today is an i7 with 32GB RAM, 5TB of total storage, no floppy drives, a DVD drive that I haven't used in six years, graphics card, and a beautiful case. Is this the same computer? NO. But when did I purchase this computer? I never did, unless you go back to the early 90s -- it was always just an upgraded component along the way, and eventually evolved to what it is now.

My current road bike (the Cannondale Synapse Aluminum) has upgraded wheels and tires, newer seat, newer stem. It's on its 3rd set of pedals, second cassette, fourth chain, third set of brake pads, newer set of shift cables. ... and my next upgrade will be a new drive train from shifters to cranks/chainrings, to rear cassette and derailleurs so that I can convert it from a Shimano 105 triple 10sp to a Shimano Ultegra compact double 11sp. Still the same bike after all that. And when I get tired of the fact that one of the rack braze-ons is stripped I'll replace the frame and probably won't be calling it a new bike.

Chesterton

I feel like this is tempting fate. I suppose it's good to be *able* to do this on a tour, but my gut instinct is "if it ain't broke don't fix it".