# Chain Stop / Anti-drop devices



## tom_h (May 6, 2008)

I'm building my first carbon frame bike (Specialized S-Works Tarmac, Campy Chorus 11), and I'm starting to imagine worst-case scenarios of the bottom bracket getting all torn up and scratched up, if the chain ever drops off the small chainwheel (50-34).

Yes, I know, chains are not _supposed_ to drop off properly adjusted set-ups .. but sometimes it _does_ happen, under the transient conditions of cadence , force , and gear combinations.

The cheap/easy "dog fang" devices (eg, Third Eye) won't attach to the curved, bulbous BB area of the Tarmac frame.

I've come across one custom device that looks like it would work, and shouldn't be _too_ expensive to fabricate -- see pic below. 

Any other suggestions? Or, "stop worrying about it" ;-)

source: http://www.cyclingnews.com/photos/2007/tech/probikes/?id=/photos/2007/tech/probikes/ballan_wilier07/BallanBike007 
..


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## danl1 (Jul 23, 2005)

The very fact that they're seen on so many pro's bikes should lay to rest that 'properly adjusted' or 'with skillful shifting' nonsense. Yes, it's true that it will minimize the effect, but chain drops will occasionally happen.

I built one just as you've described. Here's the thread where I've described it, complete with WAY too many words and completely useless pictures. Bottom line: A $2 arrowshaft and 15 minutes of fiddling around does an outstanding job.

http://forums.roadbikereview.com/showthread.php?t=113455


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## tom_h (May 6, 2008)

very clever! (That thread didn't come up on my search -- I should just use google search instead of the forum's search).

http://www.velonews.com/photo/39313


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## mds (Dec 16, 2008)

Another possibility: Get a Deda dog fang, some double-sided sticky foam tape and a zip tie. Throw away the bolt, loop the zip tie through the bolt hole and nut and apply the sticky to help keep it all in place. There is a pic on the net somewhere of this on a pro bike.


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## tarwheel2 (Jul 7, 2005)

Chain watchers work. I have them on almost all of my bikes now. It doesn't matter how well your FD is adjusted, your bike will occasionally throw a chain without one. 

Just by coincidence, I came across this article on roadbikerider.com today about chain-watching devices. You can download plans from their site for $3.99. Scroll down the page to find the article.

http://www.roadbikerider.com/index.htm


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## danl1 (Jul 23, 2005)

tarwheel2 said:


> Chain watchers work. I have them on almost all of my bikes now. It doesn't matter how well your FD is adjusted, your bike will occasionally throw a chain without one.
> 
> Just by coincidence, I came across this article on roadbikerider.com today about chain-watching devices. You can download plans from their site for $3.99. Scroll down the page to find the article.
> 
> http://www.roadbikerider.com/index.htm


That's a good approach. It seems like that might take up quite a few threads on the mounting bolt, but it doesn't look like they replaced it with a longer one. I don't know if it's a problem or not, but it might be something to think about. It might depend if one is using a clamp-on or braze-on adaptor, but I don't recall mine having a bunch of extra threads. 

(I wrote to Al, too. I'm deeply hurt that they didn't choose me.:cryin: )

OK, I'm better now.


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## Guest (Feb 12, 2009)

There was one of similar design on Velonews the other day, I believe it was on one of the riders bikes from the female Cervelo Test team. I looked up the company but they didn't have anything on their site.


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## cyclust (Sep 8, 2004)

For me, a chain watcher device is a must. I trade bikes quite frequently [usually on ebay] and a chain suck scar just kills the resale of a frame, especially a carbon frame. A $3 chain watcher can save me hundreds in depreciation.


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## cxwrench (Nov 9, 2004)

kytyree said:


> There was one of similar design on Velonews the other day, I believe it was on one of the riders bikes from the female Cervelo Test team. I looked up the company but they didn't have anything on their site.


kristin runs a pretty cool cnc'd aluminum one that her husband designed and a friend of his w/ a cnc mill machined. it's really simple, and totally does the job. looks a lot like the one on ballan's bike, but cnc'd. it attaches w/ the frt derailleur bolt and rests against the frame just above the bb on her soloist.


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## DS1239622 (Mar 21, 2007)

In the spirit of the thread...

Im fairly new to road biking and have a triple crankset. However I spend 99.9% of my time in the middle and largest chain ring. If I drop a chain in the middle chain ring will the smallest chain ring act as kind of a pseudo 'chain stopper' or will the chain continue past the smallest chain ring and get 'sucked' into the frame? Luckily I haven't yet dropped a chain and had to find out first hand.


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## tom_h (May 6, 2008)

DS1239622 said:


> ... If I drop a chain in the middle chain ring will the smallest chain ring act as kind of a pseudo 'chain stopper' or will the chain continue past the smallest chain ring and get 'sucked' into the frame?


Extremely unlikely chain would skip past the small chainring and onto the frame.


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## FatTireFred (Jan 31, 2005)

tom_h said:


> Extremely unlikely chain would skip past the small chainring and onto the frame.




chainsuck is a very bad thing, esp on triples. it happens








.


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## DS1239622 (Mar 21, 2007)

So I've got two conflicting opinions. One says don't worry about chain suck on triples when in the medium or large chain ring, its unlikely to make it past the small chain ring. The other says it still happens and is especially devastating on triples. By default I need a third opinion to break the tie.. Any takers? Im torn between ignoring it and letting nature take its course and fabricating some broken arrow contraption to prevent it.


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## tom_h (May 6, 2008)

Is your seat tube round, all the way down to the bottom bracket? Then I would just install a Third Eye or Deda brand of "dog fang" -- inexpensive & works well.

If you've got an oval or bulbous seat tube , then a custom fabrication is needed -- my original post.

But , you did ask about shifting from _largest to middle_ chain ring -- I still think probability is nil of overshooting beyond the small ring. OTOH, if you're in the middle ring & shifting to small ring, then yes, chain _may_ drop off.

Note that "chain suck" is a different problem than overshifting beyond the smallest chain ring. An anti-drop device will _not_ prevent chain suck.

From what I understand, chain suck is more likely to befall a Mtn Bike, as their chain rings are more apt to get damaged and/or clogged with mud. I've never had a road bike partner experience chain suck.

http://www.gvtc.com/~ngear/chainsuck.html
_http://www.sheldonbrown.com/gloss_ch.html_


<DT>*Chain suck*



<DD>_Chain suck occurs primarily when downshifting under load from the middle to the smallest chainring. The bottom run of the chain may not immediately disengage from the middle ring, and can get carried upward until it wedges betwixt the chainwheels and the right chainstay. _
_This jams the crankset. Since you probably wouldn't have been shifting to the granny if you weren't already climbing, the sudden lock-up of the drive train deprives you of what little momentum you had, and you are very likely to stall and fall. _
_Chain suck is commonly caused by bent chainring teeth, dirty chains, or, occasionally, burrs on the teeth of new chainwheels. __Jonathan Levy has an extensive *Web site about Chain Suck*_


</DD>


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## Dr_John (Oct 11, 2005)

> The very fact that they're seen on so many pro's bikes should lay to rest that 'properly adjusted' or 'with skillful shifting' nonsense. Yes, it's true that it will minimize the effect, but chain drops will occasionally happen.


Thank you. :thumbsup: I've dropped a chain exactly once, and to outside, in my recent cycling life. I mentioned in a thread here that it really obviously scratched up my Ultegra SL; the topic of the thread was the 'durability' of the Ultegra SL finish. Of course I got the 'learn to adjust your front derailleur, idiot' comments. Apparently the Astana mechanics can't adjust front derailleurs either, and you'd think Lance would know how to shift (photo by RBR member K-Zero)


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## russotto (Oct 3, 2005)

Wow, nice picture. I'd have expected a stream of profanity coming out of his mouth sufficient to fog the image...

One thing about the Dog Fang I learned the hard way. It only works when it's in the right place. If you naively trust your LBS to put it in the right place and they put it way below that, then not only does the chain jump off anyway, but it gets caught between the Fang and chainring so it's really hard to get back on.


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## Mel Erickson (Feb 3, 2004)

They're both right. If you are simply shifting between the big and middle rings it's highly unlikely the chain will fall off the middle, miss the small ring and fall on the BB. However, If you're shifting from the middle to the small ring then chain suck can happen as often as it happens on a double and quite possibly more often. It certainly happens enough on the triple on my tandem that I have a catcher installed. Tandems are even more susceptible to chain suck than singles with a triple but chain suck is probably more likely on a triple than a double when shifting from the middle to small rings.


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## Oxtox (Aug 16, 2006)

My Ultegra 10 setup shifts flawlessly for months and then, with no discernible change in my technique, it tosses the chain...

so, I just ordered a Jump Stop from Nick...he's just down the road in Boerne..who knew?

http://www.gvtc.com/~ngear/whatis.html

decent looking piece, totally affordable ($12) and he doesn't even ask for upfront payment...


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## Argentius (Aug 26, 2004)

*Nice insurance*

You'll drop the chain sometimes. It happens.

Chain stoppers work nicely.


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## tom_h (May 6, 2008)

The N-gear Jump Stop seems one of the better designed & engineered of the devices, and I have one on my MTB.

It is a little bulkier than a "dog fang" and may not easily fit the more cramped BB region of some road bikes. Eg, it wouldn't fit my aluminum road bike w/ a triple crank.


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## Nick29 (Aug 3, 2008)

In that picture of Armstrong, it looks like the chain has fallen off the big ring, and not between the small ring and seat tube. The times I've dropped my chain, it has ended up between the crank and big ring, but has happened while shifting to the small ring. Is this something that would be helped by a chain stopper (it doesn't seem like it would be), or am I screwing something up? I've been leaning toward the latter, but can't figure out what I'm doing wrong.


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## Mel Erickson (Feb 3, 2004)

I like the allen wrench design the best. Theoretically it should fit any bike. The type that have a band clamp around the seat tube have trouble with anything but a round tube. Plus, like tom h said, even some round tube bikes have a space problemo in the seat tube/bb area.


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## Guest (Feb 18, 2009)

Mel Erickson said:


> I like the allen wrench design the best. Theoretically it should fit any bike. The type that have a band clamp around the seat tube have trouble with anything but a round tube. Plus, like tom h said, even some round tube bikes have a space problemo in the seat tube/bb area.



That kind is also good for cx bikes as on some frames the "pulley" is in about the same place the dog fang would be so there is no way to modify it to fit.


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## bluemarinoni (Mar 15, 2007)

Dropping a chain to the outside cannot be helped by a chain-stop-drop device. The few times I've dropped to the outside I've attributed to overly aggressive shifting behavior. My f.d. is trimmed, as far as I can tell, perfectly. (If I set outer adjust screw any further in, it results in chain rub in largest gear) I suspect Lance's f.d. was trimmed even better than mine. It happens. I don't race, and simply remind myself to be conscious of my shifting behavior, and don't drop chains to the outside. 

With skill, you can quickly pick the chain back up onto the big ring by pedaling just so, and hardly miss a beat, a skill I picked up when I was younger and rode mtb's.


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## tom_h (May 6, 2008)

*New: K-Edge chain catcher*

I may have found a chain stop device I like, and it's nearly "on the shelf" (May 2009) ... no price yet.

story:
http://velonews.com/article/90511/born-for-beijing-the-k-edge-chain-catcher-goes-into

manufacturer:
http://www.aceco.com/kedge.html


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## DS1239622 (Mar 21, 2007)

Very cool. Looks like you need a braze-on style front derailleur though. Doh!


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## DrSmile (Jul 22, 2006)

I just installed a dogfang on my 08 Tarmac SL. It fits just fine.


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## tom_h (May 6, 2008)

DS1239622 said:


> Very cool. Looks like you need a braze-on style front derailleur though. Doh!





DrSmile said:


> I just installed a dogfang on my 08 Tarmac SL. It fits just fine.


Well, that's been my issue all along ... the curved, bulbous BB region on my 09 SWorks Tarmac won't accomodate any hose-clamp-style device, it has to be attached to the "braze on" clamp.

Kind of suprised how a regular 'dog fang' could be made to work on an 08 Tarmac SL -- don't they have the same oversized, curved BB region , as the 2009 models?


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## Dr_John (Oct 11, 2005)

> Kind of suprised how a regular 'dog fang' could be made to work on an 08 Tarmac SL -- don't they have the same oversized, curved BB region , as the 2009 models?


No. It's pretty conventional, and I don't see why a normal dog fang wouldn't work:


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## tom_h (May 6, 2008)

*Frame design changed ...*

Apparently the frame design has changed,since then ... a dog-fang device would definitely _not_ work for me (I tried it!) . Your 08 Tarmac has a clamp-on derailler, so I'd expect a clamp-on dog-fang device would also have no problem.​ 
Below is a pic of the BB region of my _2009 S-Works Tarmac SL2_ frame.

The seat tube is actually more squarish than round, plus it has a tapered cross-section that gets monotonically narrower toward the top. 

Because I have a compact 50-34 crank, the dog-fang would have to positioned even _lower_ than with a 53-39 crank ... there's nothing round to clamp on.
.


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## DrSmile (Jul 22, 2006)

I guess there are advantages then to the 08


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## g-Bike (Jan 25, 2006)

Looks like they are coming out May 1, I will have one for my Tarmac SL Pro for the seat tube area where a deda would fit is way too large and square. This little puppy is going to be nice to have.


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## LO^OK (Feb 1, 2008)

tom_h said:


> Apparently the frame design has changed,since then ... a dog-fang device would definitely _not_ work for me (I tried it!) . Your 08 Tarmac has a clamp-on derailler, so I'd expect a clamp-on dog-fang device would also have no problem.​
> Below is a pic of the BB region of my _2009 S-Works Tarmac SL2_ frame.
> 
> The seat tube is actually more squarish than round, plus it has a tapered cross-section that gets monotonically narrower toward the top.
> ...


Whoever worked on Valverde's Opera cut the dog-fang and used a zip tie to reattach it. Hope this helps. Another image in the link:

http://www.cyclingnews.com/photos/2005/tour05/tech/?id=valverde_opera/IMG_0451


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## Stogaguy (Feb 11, 2006)

*+1*

I agree completely with your comments regarding "proper adjustment" and "skillful shifting" often not being the cause of a dropped chain. Personally, I feel that rider skill has very little to do with it. IMHO, the true culprit is the "slap shot" all-at-once action of modern indexed shifters. I will readily admit that modern shifters are, in most respects, a big improvement over old friction designs. However, other than picking your timing, you can do very little to control FD downshifts. As a result, I feel that some sort of "chain keeper" should be included on most modern setups. It is just good cheep insurance.


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## Dr_John (Oct 11, 2005)

> Whoever worked on Valverde's Opera cut the dog-fang and used a zip tie to reattach it. Hope this helps.


The Third Eye dog fang is a design along the same lines:

http://www.excelsports.com/new.asp?...n+Watcher&vendorCode=THIRDEYE&major=8&minor=5



> I agree completely with your comments regarding "proper adjustment" and "skillful shifting" often not being the cause of a dropped chain. Personally, I feel that rider skill has very little to do with it. IMHO, the true culprit is the "slap shot" all-at-once action of modern indexed shifters. I will readily admit that modern shifters are, in most respects, a big improvement over old friction designs. However, other than picking your timing, you can do very little to control FD downshifts. As a result, I feel that some sort of "chain keeper" should be included on most modern setups. It is just good cheep insurance.


And just to add, I've thrown chains on railroad crossings while not even shifting.


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## ssing20 (Aug 1, 2007)

tom_h said:


> I may have found a chain stop device I like, and it's nearly "on the shelf" (May 2009) ... no price yet.
> 
> story:
> http://velonews.com/article/90511/born-for-beijing-the-k-edge-chain-catcher-goes-into
> ...


The K-Edge Chain Catcher is now for sale to the public. Unfortunately, it costs $45 bucks!
http://www.acecosportgroup.com/content/products/


Personally, I made my own one by following the directions on RoadBikeRider.com
Cost: $4 for the instructions and about $3 in materials. Here's a pic of it.
The K-Edge is the 2nd pic below in blue.


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## albert owen (Jul 7, 2008)

I have stuck small, clear drawer stops (the little rubbery things that stop drawers banging when closed) to the frame around the bottom bracker area. On the odd occasion when the chain overshoots the little ring, no harm is done. They are all but invisible and do the job for £0.50p


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## minstrie (Jun 13, 2005)

albert owen said:


> I have stuck small, clear drawer stops (the little rubbery things that stop drawers banging when closed) to the frame around the bottom bracker area. On the odd occasion when the chain overshoots the little ring, no harm is done. They are all but invisible and do the job for £0.50p


Now that's a good idea!

Thanks,

Minstrie


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## rook (Apr 5, 2009)

*I still don't think most people need it, unless you are riding cobbles or something*



Stogaguy said:


> I agree completely with your comments regarding "proper adjustment" and "skillful shifting" often not being the cause of a dropped chain. Personally, I feel that rider skill has very little to do with it. IMHO, the true culprit is the "slap shot" all-at-once action of modern indexed shifters. I will readily admit that modern shifters are, in most respects, a big improvement over old friction designs. However, other than picking your timing, you can do very little to control FD downshifts. As a result, I feel that some sort of "chain keeper" should be included on most modern setups. It is just good cheep insurance.




good insight. I kinda agree and disagree to a certain extent. You are totally right on about modern front shifting being a "slap shot" as you described. The quick shifting is really nice when you need it. However, while the modern indexed shifting is vastly better than the old friction design, I actually prefer the friction shifting for the front derailler.

IMO, indexing of the front shifting is not significantly better than the old friction front shifting. There are only two rings up front anyway, so you don't experience the super ease and speed gains you do like with rear cogs. I hate the loss fine-tuning ability of the front shifting mechanisms of my old friction front shifters because of today's indexed front shifting.

This is why so many people are buying these ugly chain dropper things anyway. A properly adjusted friction front derailler would never, ever, ever need one of these anti-chansucky devices. I mean, you still don't need it much with a properly adjusted modern indexed front shifter, but I can see why people get them. These modern front shifters drop chains alot more than the old front friction shifters ever did.


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