# SS throwing chain



## luwabra (Jun 6, 2012)

Ive got my chain line straight... and the chain has been checked for stretch and its good, the cog seems alright and the chainring is good. Now why am i throwing the chain? tension? whats a good tension or a good rule of thumb to go by i understand that theres a tighter "spot" on the rotation and im wondering if I have it too tight at that spot. Thanks for the input.

This is a gravel bike geared 50/19 if that makes any difference at all.. terrain is rolling hills in iowa so pretty much FLAT most of the time.. did 55 miles yesturday and accoding to strava had 450' of elevation gain. just for background.


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## UrbanPrimitive (Jun 14, 2009)

If your chainring was designed for use with a derailleur, chances are good that there is a tight spot somewhere. That, however, is the least likely place you will throw your chain. More likely is that you have too little chain tension, or you may be measuring your chain tension at the tight spot, resulting in another place or two in the pedal rotation where your chain tension is too low. This is especially likely if your chainring isn't well centered.

If the chainring is, indeed, intended to work with a derailleur the ring and teeth are actually designed to make throwing the chain easier. On a bike with multiple chainrings that means quick and easy shifts. On a single speed is means thrown chains. That isn't insurmountable and shouldn't be considered a part that must be replaced. But it can exacerbate the problem if there are other contributing factors.

The rule of thumb I was taught for chain tension is this: While crouching next to the bike, put pressure on the pedal to take any slack out of the chain. From this position you should be able to push the chain up bit less than half an inch and down a bit less than half an inch. All said you should have a total of approximately three quarter of an inch of vertical play in your chain.

I subscribed to that rule successfully for years. Then, this year, my job changed and I had to go to another part of town. This allowed me to commute full time on my bike, but also had me on some treacherously rough pavement (Michigan roads will take your fillings and your lunch money). Riding home at night and hitting a particularly bad patch had me throw my chain a couple times and it scared the bejeezus out of me. I now keep my chain tension just a touch higher than described above and am learning where all the bad pavement is.

Your methods may vary, but that's what I've been taught and what I've had success with. Good luck and happy riding.


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## markaitch (Nov 3, 2010)

^^^thank you mr pedantic :wink:

of course, op, it is always a good idea when asking questions about one's drivetrain to post a nds pic.

i don't feel like searching it up...so tell us, is that perchance a road frame with vertical dropouts? if so, tried a chain tensioner? if not, are you hoping & praying you hit the magic gear? or maybe think about getting yourself a half-link?

or...if you have horizontal dropouts/trackends...nevermind


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## luwabra (Jun 6, 2012)

Semi horizontal drop outs and using a surly hurdy gurdy "chain tensioner". Whats a nds pic?


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## luwabra (Jun 6, 2012)

Non drive side. Got it .pic was solely for viewing pleasure. Description and question was pretty straight forward....i thought.


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## CliffordK (Jun 6, 2014)

Where are you throwing the chain? Chaining or rear sprocket? Inside or Outside?

If it is at the chainring, consider sandwiching it between two chain guards. 

Do you have enough adjustment without using the chain tensioner? You can buy half-links for chains if needed. I don't have an adult single speed, but usually with kids bikes, I set the chain pretty tight, often prying the wheel with a screwdriver, then back off just slightly so it doesn't all bind up.

Also, if you've been messing around with the chain some, run the chain over your finger or something to bend every link, and verify that you don't have any stuck links.


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## UrbanPrimitive (Jun 14, 2009)

markaitch said:


> ^^^thank you mr pedantic :wink:


I do what I can, but try to keep my secret alter ego, _Captain Know-It-All_, under your hat! :thumbsup:


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## Gregory Taylor (Mar 29, 2002)

A couple of thoughts - 

Check the chain line with a straight edge. Eyeballing it can be deceiving. While it may look straight, chances are it isn't. That said, I'll follow up that bit of advice with the observation that your chain line normally doesn't have to be utterly perfect to stay on. 

Chain tension is the obvious first place to look. You are running a tensioner and this is a gravel bike (cool, by the way!). Is it dropping over bumps? If so, that suggests that the tensioner may not be, uh, tense enough, and not in the "pop a couple of Xanax" sense of no tension. If there is an adjustment to the spring or whatever, fiddle with it. 

Focus on the tensioner again...is it lined up properly? Those things can act like a derailleur and pull the chain over (and off) the rear cog if they aren't lined up. Get out the straight edge and check.

The cog...is it a plain single speed cog, or have you pirated a cog out of an old cassette and running it on a regular cassette hub with spacers? If it is pirated, sometimes the shift ramps on the cog can cause a chain to want to move over when you are REALLY honking on it. 

Bottom line, see if you can figure out the set of circumstances where it tends to dump the most (bumps, high speed, standing on the pedals, etc.), and then figure out what that would make the chain do. In the words of the Great Zen Bike Mechanic, "be the chain...."


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## luwabra (Jun 6, 2012)

Gregory... Great stuff thanks! The chain line was set w tool/straight edge that lines up on the chainring and gives a straight line back to cog. Double checked w a tape measure its abou 1/8". The cog is a pirated old hyperglide w a bunch of 1/8 spacers to make it work. I didnt know if i would like riding 1 gear as much as i do! I have since ordered a ss cog and spacer kit. Hopefully this will remedy. Thanks for everyones input.


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## luwabra (Jun 6, 2012)

http://surlybikes.com/parts/hurdy_gurdy

the hurdy gurdy is not necessarily a chain tensioner but more an rear wheel lock. i was having problems with torquing the rear wheel into the nds chain stay. None of my QR's would hold it. The hurdy gurdy by the way has eliminated all of those problems! great little devise for anyone that is having similar problems.


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## CliffordK (Jun 6, 2014)

If it is an old cog, then it probably won't have the lifts. 

Does the cog have grooves on it?
Look at the tooth profile. Are all the teeth the same? Is the back side of the teeth square?


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## luwabra (Jun 6, 2012)

Ended up going w a ss specific cog. Far more tooth than the previous cassette robbed one. Also did a ss spacer kit instead of a slew of old cassette spacers to clean it up. Ready to roll. Thank you all for your suggestions!


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## luwabra (Jun 6, 2012)

and all is well. the chainline is good from the start.. replacing the cog to a ss specific made all the difference. Ive done 5 or 6 40-60 mile rides on it and not one problem. just an update i appreciate all input that was received.


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## Gregory Taylor (Mar 29, 2002)

luwabra said:


> and all is well. the chainline is good from the start.. replacing the cog to a ss specific made all the difference. Ive done 5 or 6 40-60 mile rides on it and not one problem. just an update i appreciate all input that was received.


Most excellent. Now....let's make that thing a fixed gear.

C'mon. You can do it. An ENO hub, a fixed cog, and some _huevos_ to go out and mix it up on a group ride while not...coasting....ever. 

Single speeds are just road bikes for people who are too confused to know when to shift. We know that you aren't one of _those_. Right?

(TOUNGE-IN-CHEEK WARNING: No, I don't really think that Single Speeds are dumbed down road bikes for the more limited among us who can't get the hang of shifting. I have a single speed. And two fixies. So before you hit "send" on an impassioned defense of the purity of coasting and the freedom from shifting....don't. It was a joke, people.)


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## JCavilia (Sep 12, 2005)

> (TOUNGE-IN-CHEEK WARNING: No, I don't really think that Single Speeds are dumbed down road bikes for the more limited among us who can't get the hang of shifting. I have a single speed. And two fixies. So before you hit "send" on an impassioned defense of the purity of coasting and the freedom from shifting....don't. It was a joke, people.)


You shouldn't joke about that, Greg. The obvious lameness of SS compared to FG is a very serious issue. 

(JK, of course).


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## Gregory Taylor (Mar 29, 2002)

Exactly. I view hipster single-speeders as nothing more than post-ironic velo vermin. If you are going one gear in order to emphasize the clean look of a derailleur-less bike over the function that is offered by changeable gears or the efficiency of a fixed set up, _then you had better be prepared to suffer for your art._ The only exceptions are (1) vintage (as in pre-WWII) cyclists, (2) BMX bikes, (3) any single speed that is actually raced in a competative event, or (4) coaster brakes. 

I dig coaster brakes.


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## JCavilia (Sep 12, 2005)

Gregory Taylor said:


> Exactly. I view hipster single-speeders as nothing more than post-ironic velo vermin. If you are going one gear in order to emphasize the clean look of a derailleur-less bike over the function that is offered by changeable gears or the efficiency of a fixed set up, _then you had better be prepared to suffer for your art._ The only exceptions are (1) vintage (as in pre-WWII) cyclists, (2) BMX bikes, (3) any single speed that is actually raced in a competative event, or (4) coaster brakes.
> 
> I dig coaster brakes.


Criteria (3) and (4) here:


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## Gregory Taylor (Mar 29, 2002)

I didn't know that the Little 500 bikes had coaster brakes! That's cool...


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## UrbanPrimitive (Jun 14, 2009)

Gregory Taylor said:


> The only exceptions are. . .


What about keeping %&$# that can break on your commuter to a minimum? Nothing borks a derailleur like being dragged through snow banks over and over again.


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## Gregory Taylor (Mar 29, 2002)

And nothing "borks" a freewheel like frozen grease or moisture. No freewheel, no derailleur, no problem. 

(I actually had that happen to me - the pawls froze and I had a zero speed...)


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## markaitch (Nov 3, 2010)

Gregory Taylor said:


> And nothing "borks" a freewheel like frozen grease or moisture. No freewheel, no derailleur, no problem.
> 
> (I actually had that happen to me - the pawls froze and I had a zero speed...)


so then poser - try getting some stones & riding fixed...


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## Gregory Taylor (Mar 29, 2002)

markaitch said:


> so then poser - try getting some stones & riding fixed...


So, Mr. Capitalizaton-Free-Reading-Comprehension-Guy, if that incontinent little outburst was directed at _me_ then why don't we try perusing this thread one more time before we decide to bust anyone's ass about getting some "stones" and riding "fixed"...


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