# Why does this happen!



## tcazes (Jul 31, 2011)

this is the second time since FRIDAY!!!!!!! its a sram pc9


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## fishcreek (Apr 10, 2007)

because you eyeball your chainline. don't blame the chain.


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## tcazes (Jul 31, 2011)

i use a ruler and set it on my chain ring and follow it back! how would you suggest do it?


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## tcazes (Jul 31, 2011)

i read the sheldon brown way and don't really understand all the math. also i was not blaming the chain.


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## mr_chrome (Jan 17, 2005)

fishcreek said:


> because you eyeball your chainline. don't blame the chain.


lemme at least say, I worked in surveying for 20 years and now I'm a science teacher - the eye sees in straight lines (i guarantee you can't see around the corner of a building without help)..........I've always eyeballed a number of alignments over the years and never had a problem........but its always the where something is viewed from as to whether it was done right or not............


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## tcazes (Jul 31, 2011)

i mean two shops have both checked my chain line when i broke it the first time and they both said i had it perfect so once again why is this happening haha


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## fishcreek (Apr 10, 2007)

chrome, i agree with you but we also have the parallax error to consider. if it is my balls that is in danger, i rather do a quick measurement and ride in peace.

tcazes, i hate math too and i apologize if i sounded like an ******* earlier.

i have nothing against bike shops but i had my own bad experiences with them so i rarely go there unless i need a spare tube.

i did a little chainline check procedure for you. i hope you like it. i made sure that there is little to no math involved.

it is the tcazes skewer test.

1. cut a skewer (you can use whatever) at exactly 67.5mm. why 67.5? it is your hub width 135mm divided by two.










2. using your skewer, measure your front chainline. measure from the center of the seat tube to the center of the chainring. mark it.










3. flip the skewer and measure the rear chainline. measure from where the frame and locknut touches to the center of the cog. now, the cog should be exactly where the tip of your skewer is. adjust the spacers if necessary.


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## tcazes (Jul 31, 2011)

THANKS!!!! and don't worry bout sounding like an [email protected]# i got thick skin its no big deal


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## fishcreek (Apr 10, 2007)

so, was it off?


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## tcazes (Jul 31, 2011)

nope spot on!! kinda excited to know how to do it now haha

btw i measured the dowl twice even though it looks like a rough cut.


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## fishcreek (Apr 10, 2007)

good job, so its not the chainline then. how do you tension your chain?


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## tcazes (Jul 31, 2011)

squeeze chain together and look for 1/8th in movement. generally run it to where there is no drag when moving the pedals


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## Stevob (Feb 27, 2009)

Is there play in the freehub bearings?


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## tcazes (Jul 31, 2011)

not any that i can see..


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## Stevob (Feb 27, 2009)

I dunno then...

...maybe it's your superhuman strength.

If you can eliminate any flex in the driveline, something that might put the chainring and cog in slightly different planes, then try a different (betterer) chain.


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## tcazes (Jul 31, 2011)

what chain would you suggest?


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## fishcreek (Apr 10, 2007)

tcazes said:


> squeeze chain together and look for 1/8th in movement. generally run it to where there is no drag when moving the pedals


i'm not sure how you can do that on magic gear.


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## Stevob (Feb 27, 2009)

I run a KMC 710SL on a 1/8" driveline, and the only time I've ever broken one of those is when I replaced the rear sprocket without renewing the chain. It really didn't like it, but I persisted through the crunching noises until I managed to break it. Stoopid me.

I'd suggest KMC 810SL for a 3/32 driveline...but that's just my suggestion.


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## tcazes (Jul 31, 2011)

???? in all honesty there is VERY little play in the chain at all. its not so tight that binds the drive train in any way but it does move ever so slightly up and down


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## umarth (Dec 5, 2007)

Can you take a couple photos of the bike and the drivetrain? Not sure that it will help, but it might.


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## Punkeyboozter (Mar 31, 2009)

always liked KMC


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## David C (May 25, 2011)

tcazes said:


> this is the second time since FRIDAY!!!!!!! its a *sram* pc9


You just find the problem.

David


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## hoolie (Sep 17, 2010)

*So glad you described skewer trick*

That is awesome simple photo instructions. Had no problems for 2 yrs eyeballing, but now I will re-measure for complete accuracy. Thanks for the sweet post.


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## jackspade (Jul 23, 2010)

That's how to measure chainline. 

Thanks Fish!


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## Bro (Dec 20, 2010)

*Hey OP....*

How do you cut the chain to correct length? Would you happen to be re-using the pins? I.E. pushing the pin halfway out so you can remove a few links, then pushing that same pin back into the side plate?


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## 1SPD (Apr 25, 2010)

Gotta go home and try this out on my fixie! Not that I can really add any spacers to the rear thread on style hub but worth knowing. I can tell you right now that I believe the chain line is off on that POS. But the rear hub has some play in it as well so I already know that isn't helping things any!

Great little measuring technique there!


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## fishcreek (Apr 10, 2007)

i am kinda disappointed if we cannot dig into this and i refuse to believe that the chain will snap twice just because someone is using a specific brand of chain. its like being hit by lightning twice, it is not convincing unless you are doing something wrong. erik brought up a good point about reusing the same pin, maybe you are not pushing it all the way in.

we are curious to see the whole drivetrain, post a picture of the whole thing so we can be all at the same page.

we can always blame the equipment on this and your *old thread*, and by all means im cool with that, but not cool because i wasted my time just like everyone else trying to figure out this problem.


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## b0mb3r (Feb 12, 2011)

fishcreek, thank you for the simple but effective tip! :thumbsup::thumbsup::thumbsup: (I would rep you but the site won't allow me).


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## fos'l (May 27, 2009)

Fish --- genius, too bad you can't patent the idea and start selling 67.5mm dowels.


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## umarth (Dec 5, 2007)

fishcreek said:


> i am kinda disappointed if we cannot dig into this and i refuse to believe that the chain will snap twice just because someone is using a specific brand of chain. its like being hit by lightning twice, it is not convincing unless you are doing something wrong. erik brought up a good point about reusing the same pin, maybe you are not pushing it all the way in.


Yeah, erik nailed that thought.

SRAM makes the best chains. My 8** and 9** series have lasted forever, are easy to work with and cheap. I guess this particular model could be ****. But I doubt it.


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## perttime (Aug 26, 2005)

Chainline, OK
No wobble in freehub, OK

what about...
No play in cranks or chainring?
No snags in chainring or cog teeth?
Is the chain tight enough? Not so loose that the chain can jump onto a tooth?


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## tcazes (Jul 31, 2011)

been driving all day so will get pics when all settled back down. hold on guys.


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## Birdman (Dec 31, 2003)

*Facepalm*

_Disregard - didn't see it was a new chain._

JMJ


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## Stevob (Feb 27, 2009)

At this stage, I'm willing to bet that it was weakened by the bent tooth on the chainring that you had last week...

...or did you change the chain after replacing the chainring?


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## wjphillips (Oct 13, 2008)

Erik, nailed it. I suspect it's a weak re-used pin.

I like the dowel technique. I'll definitely start using it. Thanks fish!


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## Tone No Balone (Dec 11, 2004)

i'd go with an 8spd chain myself.


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## hoolie (Sep 17, 2010)

Umarth, did you mean SRAM is the best after Shimano? Just kidding, I don't even want to go there.


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## masterofnone (Jun 21, 2009)

I eyeball my chainline, and even when its not perfect I've never had a problem. It looks like maybe the pin pulled out, yeah, maybe it was weak or wasn't fully re-inserted? I see a lot of toothmarks on the rollers like it was probably worn and time to replace it anyway. I'm sure somebody's gonna shoot down my theory but I think singlespeeding can be tougher on drivetrains, especially with stronger riders torquing harder gears uphill. I replace chains frequently at even the slightest bit of wear.


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## tcazes (Jul 31, 2011)

The chain like I stated was maybe a week old. As far as the bent tooth theory from my previous thread it had already been replaced (new cog, chain ring, chain)


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## icon149 (Aug 16, 2010)

are you "breaking" the chain and reassembling to get proper length? or using master links? if you are using a chain tool then stop it now. buy some master links and anytime you remove your chain always use a master link, and always repair a broken chain with a master link. since i stopped using chain tools and started using master links I've had far fewer problems and none on my single speed.

or blame it on super human strength and sleep well at night knowing you are more than a man.


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## MMcG (Jul 7, 2003)

Tone No Balone said:


> i'd go with an 8spd chain myself.


Me too.


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## tcazes (Jul 31, 2011)

went with a kmc x9.99 silver and seems to be doing well since i did drop the chain tool and assembled with master link :thumbsup:


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## shiggy (Dec 19, 1998)

tcazes said:


> went with a kmc x9.99 silver and seems to be doing well since i did drop the chain tool and assembled with master link :thumbsup:


ANY multi-speed chain will fail if you reuse the pins. You must use the quick link or the special pin (Shimano).

But I prefer the Wippermann Whitestar (108?) singlespeed chain. Very strong, durable, uses the old type master link and can be rejoined with the old pins.


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## tcazes (Jul 31, 2011)

yup i have learned my lesson


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## David C (May 25, 2011)

shiggy said:


> ANY multi-speed chain will fail if you reuse the pins. You must use the quick link or the special pin (Shimano).
> 
> But I prefer the Wippermann Whitestar (108?) singlespeed chain. Very strong, durable, uses the old type master link and can be rejoined with the old pins.


So are you saying that any pin that as been push far enough to pass the mushroom type end will not be reliable anymore because it won't stay in place ?

By that theory, my bikes that were purchased new with a chain already on are by default prompt to have a chain failure anytime now, since they don't have a master link or any "removable" link ?

Or are you saying that not properly reinserting the pin will cause the chain to fail ?

If the first answer is yes, then I'm a crazy living jackass and I should die in a few second the next time I will ride my 5 year old bike with his 5 year old chain.

David


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## boomn (Jul 6, 2007)

David C said:


> So are you saying that any pin that as been push far enough to pass the mushroom type end will not be reliable anymore because it won't stay in place ?
> 
> By that theory, my bikes that were purchased new with a chain already on are by default prompt to have a chain failure anytime now, since they don't have a master link or any "removable" link ?
> 
> ...


No, like Shiggy said, for chains such as Shimano that don't use master links there are special replacement pins that you buy separately to replace any pins you remove. These should not be reused either


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## diabolicaldan (Feb 8, 2010)

Fishcreek... absolute genius in simplicity... going to use this technique to help align my Yess tensioner.

Cheers,
Dan


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## fishcreek (Apr 10, 2007)

hey, no prob guys. and thanks for the +reps from everyone. 

btw, how do you guys line up your handlebars, like perfectly straight with the wheels?


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## Bro (Dec 20, 2010)

fishcreek said:


> hey, no prob guys. and thanks for the +reps from everyone.
> 
> btw, how do you guys line up your handlebars, like perfectly straight with the wheels?


I put my bar perpendicular to the wheel.


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## David C (May 25, 2011)

fishcreek said:


> btw, how do you guys line up your handlebars, like perfectly straight with the wheels?


That's called eyeballing. It will only be perfectly straight in your mind. Kinda lining up your saddle... it's perfect when you decide it is. I think my trail bike have the bar a little bit to the right... But it feels like home every times...

But for your chain-line, it won't work that way 

David


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## fishcreek (Apr 10, 2007)

haha, that's what i thought. and thank you, i mount the bars perpendicular to the wheel too. :thumbsup:


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## rensho (Mar 8, 2004)

David C said:


> So are you saying that any pin that as been push far enough to pass the mushroom type end will not be reliable anymore because it won't stay in place ?
> 
> By that theory, my bikes that were purchased new with a chain already on are by default prompt to have a chain failure anytime now, since they don't have a master link or any "removable" link ?
> 
> ...


Even the Shimano pins will fail at the plate, as the plate is weakened after the pin has pushed through on removal. My first broken chain was a DA/XTR chain that I used the Shimano pin on only days before.

I make a habit of never reusing the plate on the chain, and just use quicklinks or the masterlinks.


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## David C (May 25, 2011)

rensho said:


> Even the Shimano pins will fail at the plate, as the plate is weakened after the pin has pushed through on removal. My first broken chain was a DA/XTR chain that I used the Shimano pin on only days before.
> 
> I make a habit of never reusing the plate on the chain, and just use quicklinks or the masterlinks.


Ok, then I will die today. Happy knowing you.

David


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## boomn (Jul 6, 2007)

David C said:


> Ok, then I will die today. Happy knowing you.
> 
> David


There is a difference between "less than ideal" and "really bad", and between "more likely to fail" and "you are guaranteed to die". Maybe nuances just aren't your thing?


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## David C (May 25, 2011)

boomn said:


> There is a difference between "less than ideal" and "really bad", and between "more likely to fail" and "you are guaranteed to die". Maybe nuances just aren't your thing?


Nope, me its all or nothing... I don't wanna be a living-dead... So we will see.

But I had to say I never had any experience of such thing on my bikes, but my friend's 1996 tandem bike had a pin going out of it original back chain this summer, without even knowing it... and no chain break. I simply pushed it back in and everything was fine... So since he never moves any pins off the chain, should this Shimano HG chain had a bad factory pin or what ? Or maybe it was the "special" pin that came off 15 years later...

So I should buy a master link for every single one of my bikes ?... Damn, those forums are getting pricey...

David


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## cbrock450 (Apr 18, 2008)

I swapped cogs and i had to add a link to my chain and it broke twice in one ride. I checked and made sure the new link was not binding and it seemed perfect but snap and then snap again. From here on out i have a chain for each cog. I will never add links to a chain.


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## tcazes (Jul 31, 2011)

just have to use a master link


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## nickcarll (Sep 4, 2007)

done that a time or two.. when u cut the chain down to size did you measure twice cut once? and did you use a master link? whenmine broke that exact way it was because i had spiced the chain together. using a chain tool instead of a master link to connect it. meaning i had pressed out a pin the pressed it back in... i chalked it up to mine own stupidity


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## ozzybmx (Jun 30, 2008)

Tried to +rep you Fish but you'll have to wait till i turn the 100 over 

Im off to make a lil stick up and check my chainline.


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## austinTRON (Mar 31, 2013)

Disregard, went to reply when I didn't realize there was another page of posts. sry.


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## blackgriffen_1 (May 18, 2010)

fishcreek said:


> hey, no prob guys. and thanks for the +reps from everyone.
> 
> btw, how do you guys line up your handlebars, like perfectly straight with the wheels?


Actually, now that you mention it . . . I definitely use a 2"x6" length I have in my wood pile to align the dropouts with the stem face, works every time. :thumbsup:

Also, we definitely went over reusing pins in a recent thread, everyone seemed to agree there that peening the pin ends would do the trick, and in my personal practice of the method it has not resulted in any broken chains.


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## maximo (Nov 2, 2011)

Bro is right pushing the pins back in is what is going on.


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## divernick (May 6, 2011)

I use a KMC Z610HX chain with the supplied masterlink / quicklink that comes with the chain. Never had any issues. The chain's cheap too at around $10.

I have also used plenty of Shimano 6/7/8 speed chains and have rejoined using the pins, also never had an issue. Your chaintool technique must be spot on though.


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## worrptangl (Jun 23, 2009)

I use the KMC Z610HX and have used the K810 and Z8.93 chains. They are 3/32 but the 1/8 versions the Z510 and K710 are just as good.


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## captnpenguin (Dec 2, 2011)

Steel frame flex?


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