How many times can I break a chain before it's time for a new one?
 

I broke my chain last night in two places.
I think it was my fault.

I thought my chain was to long, so I took out a link.
Then I put a some smaller crank rings on it, so I took out another link.
I didn't like it, so put a some larger crank rings back on it,
so I put a link back in.

So that was three times I've taken the chain apart and put back together.
It was only on the third time that I noticed that there was one link different
from all the others.

I thought I read somewhere that once you punch out a pin,
the chain is never the same.

Is this true?

And what did I do wrong?

What type (8-speed, 10-speed, old school?) and brand (Shimano, KMC, SRAM) of chain. Some chains can be broken and reassembled or lengthened without using a master link. Others can't.

I don't keep track of how often I break chains. Break with a chain tool, that is; I have never "broken" one in use. I think that "once you punch out a pin" statement is false. This assumes you are using the tool correctly, keeping the pin ends even, making sure you aren't leaving tight links, etc.

I do think mixing brands, as it sounds like you did, is probably a bad idea.

If you are using quick links, my understanding is those aren't supposed to be used multiple times, but honestly I do that too and haven't had a problem. Maybe I'm just lucky or not very strong.

The thinner the chain (higher number of speeds), the more important this becomes. 10sp shimano is...finicky.

I use a chain tool and have removed pins to 'break' the chain many a times for each chain. I never thought/knew/heard it would ruin the chain...if that's true then people wouldn't reuse chains over and again after doing maintenance.
Ive broken one chain probably 8 times alone in the past couple months while working on building a vintage bike up from scratch. The chain is new and is sticky at the point where the pin is reinserted, but some simple lateral movement and the link frees up.

I have never broken a chain on a road bike. (I've broken a couple MTB chains, but that was due to impacts.) I use primarily vintage Regina and Sedis chains and they have never given me any problems, despite countless removals. I'm fairly meticulous about keeping a clean drivetrain, so I may take off my chains for soaking/cleaning 3-6 times per year depending on the bike. I used to do a complete strip down & overhaul about once per month during my racing days. It's important that the pin go back in straight, or you run the risk of the pin bending/pushing the outer plate when it is re-installed. I suspect this (a slightly bent chain link plate) is why most chains break.

Your experience matches that of other studies previously conducted..
http://i193.photobucket.com/albums/z...psvdlysg7m.jpg

Nobody ever defines how their chain "broke" in these threads... did a side plate crack? Did a pin pull out of a side plate? What brand/model of chain was it?

With 8-speed and narrower chains, it's not recommended to push a regular pin back in after breaking (in the sense of pushing out a pin on purpose) the chain. Use the special pin(s), or better yet, quick link(s).

It sounds like the op is referring to using a chain tool or "breaker" and not actually breaking a chain due to trauma in which case I'd say do it until your fingers bleed. As long as it's not the same link each time and you detension it after putting it back together I think it would be fine.

When I say breaking the chain, I mean taking it apart with
a chain breaker tool.
When I say the chain broke, I'm stuck on the side of the road.

The chain was new.
Mated to a six speed NOS Suntour freewheel.

I won't say I knew what I was doing when I took apart the chain.
First time for everything.

The drive train didn't sound or feel right on the ride until it broke.
I removed the bad link on the road and fixed it,
but it still sounded bad, so on closer inspection, found another bad link,
that I removed also.

Rode fine after that. Rode twenty miles home, with a couple of hill climbs.

I'm going to replace the chain, if just for peace of mind.

Just trying to analyze the problem, I really don't want to get stuck out somewhere.

The broken link, and the link that almost broke.

http://i48.photobucket.com/albums/f2...ps8gcjdoum.jpg

BTW. I was maintaining my own with a dozen carbon craplets,
until the d*** h**** dropped me after this happened.
So is it only the CV guys that carry tools?

My thought is that each time a chain is disassembled, and reassembled, one looses a few percent of the original strength for that one link. 10%? And this creates a potential failure point.

As others have mentioned, it probably isn't bad to do it a few times as long as one is using different links.

100 times per chain?

I usually do a one-shot thing. Once the chain goes on a bike, it stays on the bike until it is ready to be removed and replaced.

I've been using the HG73 9S chains. I bought a few of those replaceable pins, but seem to have misplaced them. So, on 2 chains so far, I've just pushed the pins out and back in. So far, they're at about 90% worn out without failure. I marked the link on the second chain... just so I'll know in case of failure. I ended up with a kink on the other side of the chain that had to be worked out. And, I've started carrying a chain tool... just in case.

Does being a Clydesdale mashing up hills make a difference?

Here's a detailed discussion of this issue: Park Tool Co. » ParkTool Blog » Chain Installation - Derailleur Bikes

Older (i.e. pre-8-speed) chains don't have any issues that I know of being split and then reassembled with a chain tool. However newer chains definitely do. Note that Shimano chain pins have mushroomed heads that are destroyed whenever you use a chain tool to break the chain and you must use a special rivet when you replace these. If you reuse the regular link pin then I think you're at high risk of breaking the chain on the road. I don't think SRAM chains have the same type of chain pins but I avoid splitting them with a chain tool and since all SRAM chains come with a master link this seems to strongly suggest that you should always split them using that rather than a chain tool. I did break a SRAM chain while riding about a year ago and I had been messing with lengthening/shortening the chain using a chain tool, so I'm guessing that the chain tool may have resulted in a damaged link pin.

I know for sure that the manufacturers of really narrow chains (10 speed etc) say to never reuse link pins.

My policy these days is to always use a master link to separate or lengthen the chain.

I can't say... I think I have the most problem during accelerations, and not particularly on hills,but do mash out the power.

My last few broken chains.

• I think I broke a very old chain up in Portland, crossing Beaverton Hillsdale HWY, I think I probably took off from a stop light. That was a few years ago, and the chain was probably overly worn.
• Taking my cargo bike out for its initial test ride, using generic 3/32 chains, broke the chain twice in the first 2 days, and decided to throw it out and go with the HG73. No big hills, but perhaps a bit of extra resistance with acceleration. Crunchy Shifting?
• A used gruppo came with a MKS quick link and used chain. After 100 miles or so, the chain broke and the quick link vanished at the first stop sign away from my house, also probably accelerating and shifting. Am I not supposed to re-use the quick links? The chain was too short without it :( That did taint me away from using the quick links.

As I mentioned earlier, after the third time I took the chain apart,
I noticed a link like this.

Isn't there a dumb ass thread going.
http://upload.wikimedia.org/wikipedi...mpowerlink.jpg
Not my chain.

This looks like a modern, riveted chain that requires a master link to re-join the ends when opened. Driving the rivet out with a chain tool destroys the peening that holds the link together. If you re-join the ends without a master link, the damaged rivet fails to hold the link reliably. I suspect this might be what happened to you.

buy several chains so you can add sections and new quick links to join them ,

since there is no good way to make a damaged chain longer with out shortening it and adding a new section.

Older full bushing chains when freewheels had Only 5 or wide 6 speeds had pins longer than the chain is wide, were able to be lengthened and shortened.

but the need to sell 7,8,9,10&11 speed cassettes , chains the pins were flush with the outer plate, were required , and only the chain making machine starts out with
the pin being riveted over an un altered link plate.

the link plate hole gets stretched as it comes off the pin, so has to be removed.. discarded.

But it's so much harder to put the chain in the ultra-sonic cleaner while it's still on the bike. ;)

This forum is full or unqualified statements like this. This is a subjective opinion with no explanation.

My experience is you can break a shimano chain as many times as you wish. Just be sure to only break factory pins and never a replacement pin and always use a replacement pin. I use shimano chains on campy, sram and shimano bikes. Why? I feel personally that they are quieter, shift better and last longer. That is my opinion based on my years or riding and time spent working on 1000s of bikes in a shop full time from 2008-end of 2011. Have things changed? Possibly and probably, but I am sure new 8/9 and 10 speed shimano chains are the same as ever. Use a replacement pin, it's super easy to use, follow the instructions and you won't have any trouble.

Agreed and most chains will go in the Ultra Sonic at least once a year. If the bike is seeing high enough mileage to need cleaning annually, there is no way the chain will last two seasons anyway.

modern chains cannot have the pin re-used. It must be pushed all the way out and discarded. Campagnolo takes it a step further and the outer places of the broken link must be discarded and replaced with new links! Sram uses master links (as does KMC) so you "cut" the chain and install you master and always use that to take it on and off. Shimano and campagnolo require replacement pins. I prefer the pin system.

I did the above and subsequently 'broke' a shimano chain, which then got caught up within the rear derailleur and pulled it around the axle. One of the pins pulled through the plates and spread the plates apart causing them to bind in the derailleur. All I'm saying is be careful, I'm not saying to not do it. User error can have...detrimental effects (as in my case). The thinner the chain, the thinner the plates, and the less purchase they have on the pins.

I had long spoke highly of Shimano's special pins, but not so much any more.

And not that I need to "clean" my chain, since my routine lube-and-wipe with a terry cloth never allows increasing buildup of crud over time (I use a solvent-diluted type of lube).

BUT, while building up a customer's bike recently, I had the special pin push right through the chain before any noticeable torque on the handle had been noticed!
And there is sometimes the need to "change" a bike's chain, either to test a new one out (as a diagnostic), or to alter the bike's gearing.
So the KMC links (available in two 8s widths as well as 9, 10 and 11s) are a better way to go, and even cheaper than Shimano's pins in an ever-increasing number of cases!

I note that in the OP's photo (post #10 ) that the sheared-off peening is visible at the ends of the pins, assurance that those pins would never be able to support normal pedaling/shifting stress levels reliably.

Unless all of the links with pushed-out pins are replaced, the chain is a time-bomb. It doesn't look like a Shimano chain in the photo, so no special pins can fix it, the links are damaged and must be replaced.

The narrower chains and their special attachment methods may have been developed to allow those ever-growing gear counts, but make no mistake, these newer chain's designs and metallurgy offer the biggest improvement to older drivetrain's shifting that can be found, while surviving on ever-more-scant lubrication and even weighing a bit less. So I'm happy to put up with them you could say.

I would say +1 on your marking the pushed pins and carrying a chain tool, but have you ever thought what would happen if you were perhaps grabbing a shift as a car went by, and the chain broke?

This will happen sooner or later, sooner if the bike is shifted often under load, and what will likely happen is that your foot will momentarily lose it's force on the pedal as your weight falls on that leg, likely causing a sharp swerve to the side of that leg. A passing car may run you over, you may go into the deep ditch along the side of the road, and you may take out any other riders who are alongside or just behind you. At the least your shoe may hit the ground, stubbing your Sidi's toe cap (as happened to me).

I've broken a few chains over the years, and it isn't good. If it happens during a brisk out-of-saddle effort it tends to be much worse, and I've had to throw a series of left-legged kicks to the road to sustain my "balance" as I rolled to a stop. It's violent.
On another bike, a Pedersen, I broke the chain on the final, steep pitch to the finish line of the Mt. Diablo climb, but was lucky enough to be on a bike with a tall, tensed horizontal strap in place of a top tube, so caught my fall with my thigh and right cheek and was able to simply run to the finish line. But I can think of bikes I've ridden where the rear wheel might have lifted far off of the pavement!

It's unfortunate that the word didn't get out as quickly as the new breed of HG-style chains appeared. Bigger chain packaging warnings should have appeared(!) since of course so few will fully read the directions for a procedure they have done many time before!
Making matters worse, I've even heard many shop persons acting like knowledgeable mechanics claiming that using proper connecting hardware wasn't absolutely necessary, even some who claimed that they pushed old pins back in all the time, and internet geniuses followed suit, though to an ever more skeptical audience. Jeez, 25 years on and the question still comes up. The chain packaging still needs bigger, bolder warnings!

BTW
It was an 8 speed kmc chain.