# Chain Keeper/Guard for fixed gear cog?



## OffRoadRoadie (May 15, 2006)

Some of my fixed gear road riding buddies over the last few years have experienced a nasty rear wheel lock up after their chain jumped off the rear cog and jammed in-between the hub flange and fixed gear cog. Lately I've seen 2 guys crash after their chains jumped and locked up the rear wheel. This weekend it happen to a buddy on a bumpy and steep down hill at 38-39 mph, he fish tailed for 50-60 yards before dumping it:mad2: . During super high cadence (175-200+) the chain can exhibit some weird gyrations that can cause it to jump off the cog....even with proper tension and alignment , but a dual-sided cog guard should eliminate this.

Does any one make a chain keeper/guard for a fixed gear cog?:thumbsup: I've seen some of the belt drive SS CX/MTB bikes using them but those are wimpy SS bikes.

A local machinist might have a solution.


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## tihsepa (Nov 27, 2008)

How could a good chain jump off a good cog?
If there was a need for something to prevent it someone would make it. 
There isnt so they dont.
Me thinks we have a set up problem here.


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## Fixed (May 12, 2005)

*should not need it*

With correct chain tension, this should never happen. A chain tensioner, or chain tug, helps. It will maintain tension, even if the axle nuts loosen a little. I've done a whole lot of fixed gear riding in just about every road condition, and never had a chain jump. Did break a cog once, but that's something else.


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## PdxMark (Feb 3, 2004)

tihsepa said:


> How could a good chain jump off a good cog?
> If there was a need for something to prevent it someone would make it.
> There isnt so they dont.
> Me thinks we have a set up problem here.


Chain tensioner is one possible solution. A slip of the rear hub in the dropout loosens the chain tension and allows the chain to come off the cog. A chain tensioner prevents the slippage, and hence the dropped chain.


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## Dave Hickey (Jan 27, 2002)

PdxMark said:


> Chain tensioner is one possible solution. A slip of the rear hub in the dropout loosens the chain tension and allows the chain to come off the cog. A chain tensioner prevents the slippage, and hence the dropped chain.



What he said.....a good chain tensioner....


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## OffRoadRoadie (May 15, 2006)

Isn't fixed gear back-pedal pressure an issue with chain tensioners?


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## Dave Hickey (Jan 27, 2002)

OffRoadRoadie said:


> Isn't fixed gear back-pedal pressure an issue with chain tensioners?



wrong type of tensioner...

They need this


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## OffRoadRoadie (May 15, 2006)

Most of us are riding top-end steel bike from the 80's and 90's (mine is a 89 Serotta Nova Special SLX frame with horizontal drop outs). I'm running a 42x16 and a White Industries Eno Flip Flop hub, others are using a track hub with axle nuts, but a few are running re-dished free-wheel wheels with QR. The last jammed chain was on Surly Steamroller with investment cast Surly track dropouts and a single dropout chain tensioner.

I check my tension before every ride. Some of the rollers we spin down are bumpy, so with a slightly out of round chain ring (DA) and hitting a cadence of 190-209 on these rollers is a concern (gotta keep up with the coasters). I'm sure a few of the jammed chains were cause by poor maintenance (worn cog and chain), loose chain or improper alignment, but seeing a chain's wild gyrations at 190-209 rpms sure makes me want a cog guard.


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## OffRoadRoadie (May 15, 2006)

Cool. They might slow up a flat tire wheel removal but should hold the chain tension better than a QR or axle nuts.


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## OffRoadRoadie (May 15, 2006)

*Who makes these chain tensioners?*

Who makes these chain tensioners?


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## Fixed (May 12, 2005)

*Mks*



OffRoadRoadie said:


> Who makes these chain tensioners?


http://www.universalcycles.com/shopping/index.php?category=55

I like the MKS. Have several.


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## PdxMark (Feb 3, 2004)

OffRoadRoadie said:


> Cool. They might slow up a flat tire wheel removal but should hold the chain tension better than a QR or axle nuts.


The chain tensioner actually supplements the axel nuts - to keep them from slipping after they've been tightened. The tensioner isn't a substitute for the nuts. Often a tensioner on just the drive side would be enough. The usual/best chain tensioners presuppose track ends, rather than road-style drop outs. I think there are tensioners, of sorts, for road-style drop outs, but I'm not sure which of those works best.

I'd think QR would be a particularly bad fit for the conditions you describe.


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## markaitch (Nov 3, 2010)

OffRoadRoadie said:


> Most of us are riding top-end steel bike from the 80's and 90's (mine is a 89 Serotta Nova Special SLX frame with horizontal drop outs). I'm running a 42x16 and a White Industries Eno Flip Flop hub, others are using a track hub with axle nuts, but a few are running re-dished free-wheel wheels with QR. The last jammed chain was on Surly Steamroller with investment cast Surly track dropouts and a single dropout chain tensioner.
> 
> I check my tension before every ride. Some of the rollers we spin down are bumpy, so with a slightly out of round chain ring (DA) and hitting a cadence of 190-209 on these rollers is a concern (gotta keep up with the coasters). I'm sure a few of the jammed chains were cause by poor maintenance (worn cog and chain), loose chain or improper alignment, but seeing a chain's wild gyrations at 190-209 rpms sure makes me want a cog guard.


it doesn't matter how top-end your bikes are, for your group to be experiencing such a rash of chain-jumping on fixed gear bikes it must mean you guys are not setting something up properly. & why is the guy on the steamroller with trackends using a tensioner? i know a couple guys that have riden fixed for thousands of miles (& they ride hard & fast)...when i asked them earlier about this they told me it has never happened to either of them. 

anyway, here is different style chain-tug that i am using:










(edit)


> Originally Posted by *PdxMark*
> I'd think QR would be a particularly bad fit for the conditions you describe.


 i may be wrong but i think surly's tuggnuts come with a qr adaptor


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## OffRoadRoadie (May 15, 2006)

I do suspect improper set-up, and or lack of chain tension/adjustment monitoring for one guyut: . Worn cog on the Steamroller looks to be the cause there.
I still think a cog guard would add some security for the type of riding I do and the bumpy roads we use.


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## OffRoadRoadie (May 15, 2006)

Yup...supplement the axle nuts.


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## markaitch (Nov 3, 2010)

OffRoadRoadie said:


> ...The last jammed chain was on Surly Steamroller with investment cast Surly track dropouts and a single dropout chain tensioner...





OffRoadRoadie said:


> ...Worn cog on the Steamroller looks to be the cause...


i don't mean to beat a dead horse OffRoadRoadie, & i may be arguing semantics, but as you brought up the steamroller again...
when you mentioned that he uses a chain tensioner, do you mean a chain-tug like the couple pictured above? or what i think is more properly defined as a tensioner, something like this:









if your buddy is actually running 1 of these on his steamroller & it is fixed gear, not singlespeed...
it is probably the reason for his accident, make him take it off immediately!
those tensioners are absolutely not meant for use on fixed bikes, they cannot handle any back-pedal pressure. many of them include a product warning that they are only to be used with ss, never on fg.
good luck...


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## OffRoadRoadie (May 15, 2006)

Yes, chain-tug. Pretty sure he is using a Surly Tuggnut Tensioner on the drive-side but I could be wrong (we haven't seen him on the fixer since his chain jam crash).


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## DDolan (Nov 3, 2007)

markaitch said:


> i don't mean to beat a dead horse OffRoadRoadie, & i may be arguing semantics, but as you brought up the steamroller again...
> when you mentioned that he uses a chain tensioner, do you mean a chain-tug like the couple pictured above? or what i think is more properly defined as a tensioner, something like this:
> 
> 
> ...


Steamrollers don't have derailleur hangers, has to be a tug nut.


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