# What is chain suck??



## mtbks (Jun 14, 2011)

I have heard guys talking about "chain suck" on different models of bikes. What exactly is this? Might be a total noob question, but I am lost. Let the bashing begin haha. Thanks guys


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## zebrahum (Jun 29, 2005)

Chainsuck is when your chain wraps up around the crank and jams into the frame. Everyone thinks it's a design flaw in frame design but in all honesty with the exception of maybe 2 bike frames, there is no bike design that causes chainsuck. Chainsuck is caused most frequently by worn out, dirty, or unlubed drivetrains.

You could probably have used the search function to figure this all out though.


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## jeffscott (May 10, 2006)

The chain does not release from the front chain ring....and then jams in between the chain stay (swing arm) and the chain ring.

New chain with factory grease, or a muddy chain are the normal causes.


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## mtbks (Jun 14, 2011)

Thanks guys. Sorry I didn't use the search function first. My bad.


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## Guest (Jul 1, 2011)

Chain suck can also occur when the front derailleur is not positioned properly. Chainsuck can also happen when you go over a large bump, so the chain jumps off and jams itself.


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## alexbiker1 (Jun 29, 2011)

This killed my old wal mart bike


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## STT GUY (May 19, 2009)

mtbks said:


> Thanks guys. Sorry I didn't use the search function first. My bad.


Screw the search function... you're new, ask the question(s). If anyone gets thier undies in a bunch it's thier problem, not yours.

Chain suck can also be the function of a chain and chain rings that just hate each other. It does happen now and then The 08 Kona Hei-Hei 29ers came with a Shimano Chain and Race Face crank and the combo was chain-suck-o-rama. Switched chains to a SRAM and no more chain suck.

Most chain suck can be prevented with a combination of a well maintained chain and proper shifting habits.


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## emsky80 (Jul 2, 2011)

Chain suck can occur on any bike, keep the chain clean and replace before it is too worn


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## STT GUY (May 19, 2009)

emsky80 said:


> Chain suck can occur on any bike, keep the chain clean and *replace before it is too worn*


Which also keeps your from having to replace parts such as chain rings and cassettes. Chains are cheap compared to other drivetrain parts. I replace chains often, about every 90days or less with our amount of riding (80+ miles a week). I am always amazed at smooth a new chain shifts.


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## highdelll (Oct 3, 2008)

"Chain-Suck" is when it breaks and you don't have a tool to fix it on the trail

"this sucks..."


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## Moozh (Jan 20, 2010)

definitely not a symptom of worn out, unlubed or dirty drivetrains. Happens on some new bikes as well..perhaps on drivetrains not yet "broken in" or components that have not found harmony with each other yet...weird way to say it.

I have had chain suck issues on two brand new bikes in the past few years...the problems did not last long, in fact by the end of my first outing I have had no issues at all but the first time I went from middle to granny...chain went between the granny and chain stay and screwed up my pristine paint job...new car smell gone in 20 minutes.....no issues since.

Hmm..come to think of it, it was on bikes with Race Face cranks also....hmm..evolve cranks....hmm.... either way...cranks (chainrings I mean) are good solid citizens now.


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## Varaxis (Mar 16, 2010)

Chain suck looks like this:










This is the underside of the bike. The chain "rode up the backside" of the chainring and jammed between the ring and the bike's chainstays. This interrupts your pedaling and can damage your chain (twist, break, crush, etc.). Not to mention damages your frame.

There are anti chain suck devices that prevent the chain from going up the backside of the ring, by wedging itself between the frame and the teeth of the rings. They deflect the chain back down if it tries to ride up the backside of the rings. You can also find small metallic plates on chainstays to offer some extra protection dmg to a carbon frame in the event of chainsuck.

More info can be found here: https://www.fagan.co.za/Bikes/Csuck/

Link seems fishy, but here's one of the images from it and a quote:



> WHAT IS IT ?
> The chain fails to disengage from the bottom teeth of a front chain-ring ; instead the teeth snag the chain and carry it up and around the rear circumference of the ring, winding it back onto itself, and jamming it between the chain-rings and chain-stay.
> 
> Because it usually occurs unexpectedly during forceful pedalling, the chain can be permanently twisted, teeth can be damaged, and chain-stays of aluminium or carbon-fibre can also be damaged by the chain being wedged hard against them.


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## colorado_freerider (Jun 24, 2011)

*You tell em!*



STT GUY said:


> Screw the search function... you're new, ask the question(s). If anyone gets thier undies in a bunch it's thier problem, not yours.
> 
> Chain suck can also be the function of a chain and chain rings that just hate each other. It does happen now and then The 08 Kona Hei-Hei 29ers came with a Shimano Chain and Race Face crank and the combo was chain-suck-o-rama. Switched chains to a SRAM and no more chain suck.
> 
> Most chain suck can be prevented with a combination of a well maintained chain and proper shifting habits.


Some of these guys act like this is their forum and like they are shelling out good money for each post, sure somebody is but not the members... Also for those with panties that easily bunch up, Maybe Thongs are the way to go!:thumbsup:


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## mtbks (Jun 14, 2011)

Thanks for all the info guys!! I definitely have a better understanding of what chain suck is and what causes it haha. Thanks again!


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## Ericmopar (Aug 23, 2003)

Moozh said:


> definitely not a symptom of worn out, unlubed or dirty drivetrains. Happens on some new bikes as well..perhaps on drivetrains not yet "broken in" or components that have not found harmony with each other yet...weird way to say it.


Definitely is cause by wear, lube and dirt. 
In the case of wear, it's usually a new chain on old worn "hooked" chainrings. 
Dirt can cause it. 
Lubes can cause it. Especially sticky wax based lubes on a new and tight drivetrain.

It is most often caused on new bikes, by mismatched drivetrain componets and / or cheap components that don't hold tight production tolerances. 
Miss matching can include the wrong chain with the wrong gearing. In those cases, the chain will wedge onto the rings and cogs. 
In the cheap category, you can have a brand new ring or rings that aren't machined properly, so that the teeth are not spaced properly for the pins and rollers on the chain. 
Also, the chain itself may be made wrong, so that the pins and rollers are not .5" center to center.


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## Aminnow (Jun 22, 2010)

I have been plagued with chain suck.
I ride a Cannodale Rize1.

Here is the History of fixes:

1. New Front rings and chain....BYW I broke my smallest ring once also. still sucked. 

2. New chain again. still sucked

3. Went to two rings and new chain. and sucked again after a few weeks of riding. 

Here is added info. For two weeks I road a new RZ 140 while my bike was in the shop, and never experienced chain suck on that bike.

I am sending the Chain Suck article to my bike mechanic.


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## bear32 (Jun 5, 2011)

Do they make the notched plates that bolt on the underside to help prevent this anymore? I had one of those on my old Alta SX.


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## Varaxis (Mar 16, 2010)

They still are available. They work ok for hardtails. Some people just tie zip-ties there and put the connector end where the notches would be as a DIY solution.

For full suspension bikes, they might not be ideal, depending on the design. For those, there's the K-edge anti suck device. Seems expensive, but if you run expensive chains, you save money there from them not getting crushed and twisted when they jam and improves your drivetrain performance. A lot less expensive than all the "fixes" Aminnow went through too.


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## Aminnow (Jun 22, 2010)

My mechanic found that my small chain ring already showed wear and had some 'burrs' after two months of riding. ....a probable cause. 
Instead of an alloy small chain ring , I now have a steel small chain ring, for longer wear. 

All is well after the first few rides. Hopefully this will be the fix.


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## usn.mustanger (Jun 26, 2011)

I'm new to mtb'ing, and reading this thread leads me to believe that this phenomenon is inevitable. Kinda worrisome given that I just plunked down 2 large for a shiny new alloy framed bike (Cannondale Flash 29er 1). So what are the approximate odds of this happening to me, and what can I do to prevent it? 

Sent from my HTC Incredible


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## Varaxis (Mar 16, 2010)

^

Keep your drivetrain clean and chain lubed. When it happens, just back pedal to release it. Lube your chain after every 3-8 hours of riding in clean and dry conditions (depending what lube you use and conditions; usually 4-5 hours, or 2 long rides, for me); immediately after the ride if it gets wet from water crossings, puddles, mud, drizzles, etc. I sometimes carry a bottle of lube on me if I know it's gonna be wet (also helps when some plp don't lube their stuff at home).

It will usually chain suck when you're climbing a hill, especially if you are shifting into easier gears and are giving a good spurt of energy into cranking. Just apologize to anyone who might be behind ya, back pedal to release it, get off the bike, put it in your easiest gear, and then get back on and crank a bit more delicately to start, then go all out and shift in harder gears if you like.


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