Singlespeed & Fixed Gear - Fixed chain snap... yowch.

Ok guys - I've had my bit of excitement and sat down to count my lucky stars since; but yesterday I snapped my chain about halfway through an intersection, just levelling out at the bottom of a downhill. Of course instant lock up of the back wheel & cranks. Luckily for me the road was pretty wet and this enabled me to skid reasonably long, gather my wits, get to the kerb and unclipped for a pretty well controlled stop.

I guess now is the post mortem time for the chain. Just revisiting what I think I might done, or rather not done, to let this happen. I'm keen to get back on the fixie, but obviously keen to prevent this happening again.


The chain itself itself was a 3/32" KMC "Narrow" Z chain about 4 or 5 months old with about 600km on it. The running gear was the stock kit removed from my project Steamroller; ie. 17t Surly cog, Sugino 48t Ring, Sugino RD crank. I had built up the mid 80s MBK road frame as a conversion with pretty near perfect chainline, using the straight-edge method of checking.

I had been riding this quite succesfully since the build - with no funny noises, rubbing or grinding. I've been negotiating up & downhills no worries and mastering gradually more graceful trackstands.

My biggest suspicion is that I might have let the chain slack. I hadn't really checked it since the initial buildup, but noticed recently just by eye it appeared to sag a little more. Is my own laziness in not doing something about this most likely to be the culprit here?

But otherwise... what are the most common causes of chain break on fixed gears. I appreciate that there must be some different stresses in the backpedalling motion/force that a freewheel chain wouldn't experience - which is why I believe the straw that broke the camels back in my case was me controlling my descent through the downhill.

I have some photos of the deceased chain at the break - if they're of any use I can post.

Sweet. I have the same chain...

i have had chains break from bad chain alignment from the front chainring to the rear cog, but it sounds like your's was pretty good, right? i remember a mechanic once say that everytime you break a chain (with a chain breaker) and put it back together it is weaker. has that chain been broken many times?

I busted a chain from having it too tight. I won't take any guesses about the cause of your chain failure, because all of my other guesses about stuff today have been wrong.

Keep it properly tensioned, properly lubed, and ride with a brake.

most common cause of chain failure.....improper installation

there isn't more stress on a fixed gear chain. putting backpressure on is no different than pedaling forwards. It's still just chain tension.
There is probably less stress on a fixed gear chain since the chainline is straight. No lateral pressure from cross-chaining across 10 gears.

I busted a chain from having it too tight. I won't take any guesses about the cause of your chain failure, because all of my other guesses about stuff today have been wrong.

Keep it properly tensioned, properly lubed, and ride with a brake.

good point, if your front chainring was bent even a little, and your chain was very tight, then the stress put on your chain by the chainring turning would be extremely great (in the pejorative sense of the word)

good point, if your front chainring was bent even a little, and your chain was very tight, then the stress put on your chain by the chainring turning would be extremely great (in the pejorative sense of the word)


If anything my chain was slack.

I was concerned that my chainring might have been bent as from the resulting tangle/skid/wedge. Once I got it all home and pulled it apart I noticed that the entire rotation of the chainring evenly rubbed against the chain stay. Though this confused me for a minute but this was due to the chainstay having bendt out slightly. I bent it back loosely and the chain ring ran pretty true. whilst I am not sure of the exact point of rotation where the chain broke - it seemed to throw the remaining chain off and around the base of the driveside crank arm and wedge and stress things from there.

But I guess more immediate concern will be breaking out the string and alligning the chain & seat stays before I worry about the small componet replacement

most common cause of chain failure.....improper installation

there isn't more stress on a fixed gear chain. putting backpressure on is no different than pedaling forwards. It's still just chain tension.
There is probably less stress on a fixed gear chain since the chainline is straight. No lateral pressure from cross-chaining across 10 gears.

are you joking? what about the teeth bashing back against the bushings when you backpedal or resist

well.. they bash against the bushings going forward as well.. and they are circular... so I take baxtefer's point to some degree

(why do I get that can-of-worms-opening type feeling....)

My line of thinking is that more sudden staccato like movement of say, a heavier, guy like myself (just shy of 105kg or ~230lb) practising his trackstands :D with lots of rapid, to and fro movement might have also placed undue stress and weakened the chain as well.

most common cause of chain failure.....improper installation

there isn't more stress on a fixed gear chain. putting backpressure on is no different than pedaling forwards. It's still just chain tension.
There is probably less stress on a fixed gear chain since the chainline is straight. No lateral pressure from cross-chaining across 10 gears.

While this is true in many situations, how many people do you know that can break traction pedaling forward on a geared bike (the equivalent tension of skidding)?

i remember a mechanic once say that everytime you break a chain (with a chain breaker) and put it back together it is weaker. has that chain been broken many times?

Never... only the time I removed a couple links when it was new out of the box to get the right length. I bought a masterlink at the same time and used that upon installation. I hadn't even used that again since.

Not that it's probably of any significance, more coincidence; the break was only one link from the master.

Id like to see a pic of how it broke.

While this is true in many situations, how many people do you know that can break traction pedaling forward on a geared bike (the equivalent tension of skidding)?

Those situations are not equivalent. When skidding, one unweights the rear wheel to initiate the skid. When people pedal forward, they do not do this.

Some cyclists can deliver 1800 Watts. Their chains don't break. It's highly unlikely that a broken chain is actually due to stresses caused by typical urban fixed gear riding. It's really hard (i.e. impossible) to break a properly installed chain with no manufacturing defects.

I think the original suspicion of too much slack is probably correct. Originally I suspected the OP reused a pin on installation (don't do that with 9/10-speed chains), but he used a Masterlink.

Chain breaks =

1) Improper installation
2) manufacturing defect

Glad to hear you're ok.

One possibility is that you threw your chain first, then broke it.
If your chain is wound around the rear hub instead of the cog, then you will exert a bunch of sideways stress on the chain, probably enough to break it.

Ok guys - I've had my bit of excitement and sat down to count my lucky stars since; but yesterday I snapped my chain about halfway through an intersection, just levelling out at the bottom of a downhill. Of course instant lock up of the back wheel & cranks. Luckily for me the road was pretty wet and this enabled me to skid reasonably long, gather my wits, get to the kerb and unclipped for a pretty well controlled stop.

.

Please post pics of the chain.

From your assertion that you had just bottomed out from a downhill + slack chain perhaps equals thrown chain quickly followed by rear cog wrap & break with bonus skid through intersection.

Glad you're OK, though.

the chain is not the problem. Either the slack in the chain allowed it to derail slightly and the inertia of your forward movement broke the chain or the chain separated where you pushed the pin back in when installing the chain. Either way I say get another Z chain and put it on with no slack.

I would tend to agree with him throwing the chain first, then breaking it. It wouldn't make sense to me for the chain to just snap, and that would somehow lock up the wheel.

I don't know if it's of any significance, but the OP was running an odd-number cog on an even chainring. Jedi Master Sheldon contraindicates this, as it contributes to uneven chain wear (if I understand him correctly, which isn't certain). 48/17 is a pretty beefy ratio, especially with a 230lb guy mashing down suddenly-- could uneven chain wear combined with such a monster load have caused the cahin to fail?

I''m not asserting anything here, just asking, so I'd appreciate not being jumped on if I'm way off the mark...

While this is true in many situations, how many people do you know that can break traction pedaling forward on a geared bike (the equivalent tension of skidding)?

If I unweigh the rear wheel because I'm standing up like a gopher in traffic, I can break traction. It's not hard. :rolleyes:

I don't know if it's of any significance, but the OP was running an odd-number cog on an even chainring. Jedi Master Sheldon contraindicates this, as it contributes to uneven chain wear (if I understand him correctly, which isn't certain). 48/17 is a pretty beefy ratio, especially with a 230lb guy mashing down suddenly-- could uneven chain wear combined with such a monster load have caused the cahin to fail?

I''m not asserting anything here, just asking, so I'd appreciate not being jumped on if I'm way off the mark...

I *think* Sheldon is refering to uneven wear in the event that you want to replace the cog/chainring or something. If you have even numbered gearing you can always get the teeth to line up with the previous worn spots.

could the masterlink be at fault?

i don't use them because they scare me.

My biggest suspicion is that I might have let the chain slack. That would be my guess too. A slack chan can wiggle so that the top of a tooth bumps into a side plate. That can generate a LOT of force on a fixed gear.

I don't know if it's of any significance, but the OP was running an odd-number cog on an even chainring. Jedi Master Sheldon contraindicates this, as it contributes to uneven chain wear (if I understand him correctly, which isn't certain). 48/17 is a pretty beefy ratio, especially with a 230lb guy mashing down suddenly-- could uneven chain wear combined with such a monster load have caused the cahin to fail?Not clear that it's a "monster load." Indeed, it doesn't sound like it to me. The magnitude of the load is related to the size of the sprocket driving the chain, not the ratio.

Thus, the pedaling load is _less_ with a large ring like a 48 than it would be with, say, a 42.

If the force was being applied by the rear spocket, as when resisting to slow down, a 17 tooth sprocket would not pull as hard a a smaller one, say a 15, would.

Sheldon "Loose Chains Break" Brown

i would suspect:

masterlink
improper installation
chain dropping then breaking because it got stuck
manufacturer defect

i doubt 600 miles is enough to weaken a chain from just wear. i don't see how slack in the chain could've made it break. maybe it made it drop and then that force exerted on it after it got wedged in the hub made it break.

That would be my guess too. A slack chan can wiggle so that the top of a tooth bumps into a side plate. That can generate a LOT of force on a fixed gear.
Not clear that it's a "monster load." Indeed, it doesn't sound like it to me. The magnitude of the load is related to the size of the sprocket driving the chain, not the ratio.

Thus, the pedaling load is _less_ with a large ring like a 48 than it would be with, say, a 42.

If the force was being applied by the rear spocket, as when resisting to slow down, a 17 tooth sprocket would not pull as hard a a smaller one, say a 15, would.

Sheldon "Loose Chains Break" Brown

Good lord. It's spooky when he does that...amazing, but spooky.

Chain breaks =

1) Improper installation
2) manufacturing defect

or

3) A crash or a chain dropping incident physically damaging a link.

I vote for manu defect or bad install, but whatever it is, it was a freak accident. Install the next one correctly and enjoy.

While this is true in many situations, how many people do you know that can break traction pedaling forward on a geared bike (the equivalent tension of skidding)?


this guy sure doesn't have a problem (http://youtube.com/watch?v=mkNNW4PYG1s)

maybe the chain was just old(stretched)? no chain lasts forever after all. i hear a safe way to avoid this is by changing it every 6 mnths. and you don't need a Izumi super toughness either. a reg kmc should do fine

are you joking? what about the teeth bashing back against the bushings when you backpedal or resist

What about the teeth bashing back against the bushings when you engage the freewheel and are pounding up a hill?

The drive train will always be limited to whatever forces the legs can either produce or absorb.

like others have said, its either a bad chain, bad install, or both.

Thanks guys there's some interesting thought and debate going into this issue. Appreciate all your thought fodder, for sure. Though my original suspicsions if anything are slowly being confirmed amongst the noise - ie. my slackness with keeping the chain taught

Once again it was a relatively new KMC 'Z' 3/32" narrow chain; in the region of 600km (~ <400 miles) of life. It wasn't the master link that busted. Though it was only one link away from it (probably coincidence).

The photos illustrate that when it broke, the chain-ring threw the chain thereby also locking the drive-side crank at 9 o'clock as the slack was wound around the cog & hub locknuts. Also that the one remaining linkage plate at the break that wasn't lost shows that it was bent/torn outwards.

I wish I had my pics handy to post. I'm sorta trying to interpret what I can of the carnage myself - but experience from yourselves would of course be appreciated. I will post them from home tonight - in the a.m. US time.

A couple of pics as promised. Nothing too glorious; but hopefully something a with a little insight;

pic 1 : the whole shamozzle. How it locked up, how I came to a stop, how I carried the bike home and how I was able to take the photo ;)

pic 2 : the chain post mortem. though it's a bit dark, the master link is actually to the right of the shot.

pic 3 : the whole sorry mess of the chain & sprocket immediately before disection. note that the one loose end of the torn linkage shown in the previous shot is flipped up and gives you a better orientation.

That chain has clearly not been cared for.

That chain has clearly not been cared for.

rofl.. yah.. i doubt that a dirty chain is more likely to break, but damn, must be hard to pedal :)

Well, stiff links will obviously develop if its not cleaned/lubed. From the surface rust and wear shown on the inside of that link it clearly hasnt been taken care of.
He said it only had 400 miles on it.
It shouldnt look like that.

It looks like your chain was too slack, you threw your chain, and it broke while getting jammed between the hub & cog. It might not have broken if it were in better shape, but I think you would have had the same result at the bottom of that hill.

Take better care of your chain. At least look at it every week or so to see if it needs cleaning/lubing.

guys...i dont ever want this to happen to me... i dont want a mouth full of bloody chiclets.

how often do you lube, clean, align, etc...even how often should you change your chain?

how often do you lube, clean, align, etc...even how often should you change your chain?
It depends on how often you ride, if you ride in the rain, etc. Your chain needs lube when the sound if it going across your chainring and cog gets louder. Your chain needs cleaning if it looks really dirty, or if you can hear the grit in it.

Either get a chain cleaner like this one (http://tinyurl.com/2oln88) or take it off and shake it up in some simple green, kerosene, spirits or whatever else you use. Add your lube of choice conservatively -- I put 2 drops of oil on every roller, let dry, wipe off excess.

Your chain needs replacing when 12 links measure more than 12 1/8".

...and what is proper chain tension?

It looks like your chain was too slack, you threw your chain, and it broke while getting jammed between the hub & cog. It might not have broken if it were in better shape, but I think you would have had the same result at the bottom of that hill.

Take better care of your chain. At least look at it every week or so to see if it needs cleaning/lubing.

thnks littledjahn - I think you summed it up nicely.

I need to eat some humble pie about just how I well I assumed I was taking care of my chain. Being that the reactions to the pics thus far have that common theme. Whilst the outside faces of the linkage and their surface rust have bothered me... I was assuming that a few drops of white ligthning I have been giving it every coupla weeks was enough - obviously not enough. Some quick searches already reveal it's not necessarily the best lube anyway for my climate - not especially wet; but not especially dry either - which seems to be the ideal environment for the wax based lubes..

I think depending on the time of the year; I'll keep my faith in master links and rip the new chain off say, every other week and give it a thorough clean and also research a better; or at least more appropriate lube for my climate for top ups between cleans.

What I kinda hate about the topic of lubes is that most people seem to talk of particular brands. Often on this largely US based forum particular products or products aren't simply or readily available in Australia - or I get used to something and then my preferred/favourite LBS goes out of it and I have to face idiotic sales staff at other stores trying to sell me other crap when I am after something else specifically - which is why I got more into D.I.Y. in the first place.

Anyway.. with my old chain between my frame & cog and my tail between my legs... I'm off to search the other threads for little gems on the topic of chain care. I think the chain tension idea is now given. Lesson learned.

thanks guys...

3-4 parts mineral spirits to 1 part synthetic motor oil = prolink

thnks littledjahn - I think you summed it up nicely.

I need to eat some humble pie about just how I well I assumed I was taking care of my chain. Being that the reactions to the pics thus far have that common theme. Whilst the outside faces of the linkage and their surface rust have bothered me... I was assuming that a few drops of white ligthning I have been giving it every coupla weeks was enough - obviously not enough. Some quick searches already reveal it's not necessarily the best lube anyway for my climate - not especially wet; but not especially dry either - which seems to be the ideal environment for the wax based lubes..

I think depending on the time of the year; I'll keep my faith in master links and rip the new chain off say, every other week and give it a thorough clean and also research a better; or at least more appropriate lube for my climate for top ups between cleans.

What I kinda hate about the topic of lubes is that most people seem to talk of particular brands. Often on this largely US based forum particular products or products aren't simply or readily available in Australia - or I get used to something and then my preferred/favourite LBS goes out of it and I have to face idiotic sales staff at other stores trying to sell me other crap when I am after something else specifically - which is why I got more into D.I.Y. in the first place.

Anyway.. with my old chain between my frame & cog and my tail between my legs... I'm off to search the other threads for little gems on the topic of chain care. I think the chain tension idea is now given. Lesson learned.

thanks guys...

This is probably the most dignified response I've read [on these forums] from someone who has been severely criticized. That took a lot of class; nicely done.

...and what is proper chain tension?

As tight as you can possibly make it without binding! (http://www.sheldonbrown.com/fixed.html) One trick I've started using is similar to Sheldon's "Walking"...

1) Get the non-drive side in position and tighten it down so that the wheel is just slightly cocked away from the drive side.
2) Push/pull against the rim itself so that the chain is getting tight as hell. Use the whole wheel as a lever and the non-drive nut that you tightened is the pivot.
3) profit

Well, no, you don't profit, but I promise you can get the chain as tight as you want if you use that technique; and again, you want it is tight as you can make it without binding as you spin the crank.


thnks littledjahn - I think you summed it up nicely.

I need to eat some humble pie about just how I well I assumed I was taking care of my chain. Being that the reactions to the pics thus far have that common theme. Whilst the outside faces of the linkage and their surface rust have bothered me... I was assuming that a few drops of white ligthning I have been giving it every coupla weeks was enough - obviously not enough. Some quick searches already reveal it's not necessarily the best lube anyway for my climate - not especially wet; but not especially dry either - which seems to be the ideal environment for the wax based lubes..

I think depending on the time of the year; I'll keep my faith in master links and rip the new chain off say, every other week and give it a thorough clean and also research a better; or at least more appropriate lube for my climate for top ups between cleans.

What I kinda hate about the topic of lubes is that most people seem to talk of particular brands. Often on this largely US based forum particular products or products aren't simply or readily available in Australia - or I get used to something and then my preferred/favourite LBS goes out of it and I have to face idiotic sales staff at other stores trying to sell me other crap when I am after something else specifically - which is why I got more into D.I.Y. in the first place.

Anyway.. with my old chain between my frame & cog and my tail between my legs... I'm off to search the other threads for little gems on the topic of chain care. I think the chain tension idea is now given. Lesson learned.

thanks guys...

Don't beat yourself up too much; everyone makes mistakes. Think of it this way; how many people have read this thread and have learned 2nd hand how important it is to keep you chain clean, lubed, and tight? You are a farkin hero man!

-Chry

This is probably the most dignified response I've read [on these forums] from someone who has been severely criticized. That took a lot of class; nicely done.

maybe because he isn't an american?

//we suck

maybe because he isn't an american?

//we suck

Mmmm... I like to think that I have some class, and I'm an American. I don't think as*holes are a strictly American export.

Mmmm... I like to think that I have some class, and I'm an American. I don't think as*holes are a strictly American export.

true true true.... i stand corrected....

3-4 parts mineral spirits to 1 part synthetic motor oil = prolink

Now this is interesting. I was wondering if there is a generic mixture of readily available products that give me the properties of a bicycle chain lube. Similar to buying a lead additive for an older car fuel - or mixing up a 25:1 Fuel to Oil mixture for a two-stroke lawn mower or yard trimmer.

Avoiding more expensive brand names not necessarily always available to me is an attractive option.
If I'm going to the trouble of regularly getting grubby cleaning a chain - surely the extra effort of mixing up a lube concoction every once in a while is surely of neglible extra hassle.

Do any/many forum readers mix their own ?

Do any/many forum readers mix their own ?

I've used chainsaw bar oil for my chains for years. The only real difference between that and Phil Tenacious oil is that the bar oil is colored pink.

I don't know if you have a saw shop close, but you can usually get a quart for ~$3 from Home Depot.

Ok guys - I've had my bit of excitement and sat down to count my lucky stars since; but yesterday I snapped my chain about halfway through an intersection, just levelling out at the bottom of a downhill. Of course instant lock up of the back wheel & cranks. Luckily for me the road was pretty wet and this enabled me to skid reasonably long, gather my wits, get to the kerb and unclipped for a pretty well controlled stop.

I guess now is the post mortem time for the chain. Just revisiting what I think I might done, or rather not done, to let this happen. I'm keen to get back on the fixie, but obviously keen to prevent this happening again.


The chain itself itself was a 3/32" KMC "Narrow" Z chain about 4 or 5 months old with about 600km on it.


i got that far.

all you have to do is get a 1/8th, and you'll never break a chain again.

Now this is interesting. I was wondering if there is a generic mixture of readily available products that give me the properties of a bicycle chain lube. Similar to buying a lead additive for an older car fuel - or mixing up a 25:1 Fuel to Oil mixture for a two-stroke lawn mower or yard trimmer.

Avoiding more expensive brand names not necessarily always available to me is an attractive option.
If I'm going to the trouble of regularly getting grubby cleaning a chain - surely the extra effort of mixing up a lube concoction every once in a while is surely of neglible extra hassle.

Do any/many forum readers mix their own ?I used to mix up my own, thinning chainsaw chain & bar lube with a lighter oil. Once Phil Wood Tenacious Oil became available, I stopped bothering with this.

Not only is Phil the best chain lube I've ever used, it is also the very first to come in a container that seals well enough to carry in a bike bag without worrying about leakage ruining the bag!

Sheldon "Philophile" Brown

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