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What is chainsuck?
What are the causes of chainsuck?
Can I get chainsuck on a new bike?
How can I prevent chainsuck before riding?
What if I get chainsuck during a ride?

What is chainsuck?

Chainsuck is when the chain does not release from the bottom of the chainring. the chainring lifts the chain up to meet the incoming part of the chain. Because it can't carry on around the chainring and that there is a chainstay there, the chain gets jammed between the chainring and the chainstay with the following bad results:

• your forward motion is arrested instantly and you bash your knees or worse on the stem/bar
• the chain grinds nasty gashes out of the chainstays on your expensive bike
• the chain will either break or be permanently twisted or damaged.
• you may break some chain ring teeth, or bend the chain ring itself.

What are the causes of chainsuck?

Chainsuck is usually caused by a worn chain and/or chainring. When the chain wears, each link gets looser and the chain stretches in length.

The uneven tension on the chainring caused by a worn chain will start to wear away one side of each tooth on the chainring making it 'hooked' or 'shark-toothed'.

These hooks then begin to hold onto the chain as you rotate the cranks instead of releasing the chain to continue on it's journey to the rear mech.

Can I get chainsuck on a new bike?

Paradoxically, you can also get chainsuck on a new bike. That's right, in spite of what you have just read, this can happen even when the drivetrain is brand new.

In my experience, chainsuck on a new bike is caused by inclement/severe riding conditions. If you live and ride in the UK you will be okay for 10 out of 12 months. However, there will always be a period during the year when the trails are really wet and boggy. The slop and grime that gets on to your drivetrain during this period will cause chainsuck on the newest of bikes.

However it can also be caused by the sharp edges of new, ‘cheap’ stamped rings grabbing onto the chain (e.g. Shimano). More expensive CNC’d rings like Middleburn, TA and Pace will not give you problems like this. On new bikes, the chain is also a little greasy and until this wears off it could be a problem.

How can I prevent chainsuck before riding?

Pre-ride, ensure your drivetrain is regularly maintained. Make sure you aren't a victim of dirty or worn chainrings or an un-lubricated or worn chain.

Lube your chains properly – ideally one drop of quality lube per roller, only on the INSIDE of the chain. Finish Line ‘Cross Country’ with the green cap is ideal. There is no point lubing the outside (or ‘top’) of the chain, as this hardly touches any load bearing surfaces and will only pick up muck.

In practice, lubing involves rotating the pedals reasonably fast with the gears mid-block, and dribbling some lube onto the inside of the chain for a few revolutions. Don’t squeeze the bottle hard though – that will be far too much oil.

Budgeters can use standard 3-in-1, but will need to re-apply it more often. Re-lube after every bike wash and NOT with GT85!

For a new bike, if you look at a stamped ring, you will find one side has an edge that has a slight radius on it (the side the press hit down on) and the other side (normally the back) has a sharp corner where the pressed metal parted company with the un-pressed metal. Gently filing this sharp edge down on all the teeth profiles with a small half-round file may provide some relief from chain suck.

What if I get chainsuck during a ride?

During the ride there are a couple of things you can do. These are only useful in an emergency - prevention is better than the cure:

• Avoid riding through seriously boggy trails. Either take a firmer route or get off and push
• clean the crap off the chain and chainrings as much as possible. Use a rag if you have one handy or clumps of grass in an emergency.
• Spin in a lower gear than usual so that you are not putting so much tension into the chain. Listen out for the sound of chainsuck occurring. As soon as you hear or feel it occurring, back pedal and the chain should release allowing you to continue.
• Avoid using the granny ring. I find it mainly occurs in the granny ring but other riders report it occurs when shifting to and from granny ring. One factor being the small ‘radius of wrap’ (or ‘sharp angle’ that the chain has to make to wrap around the chain ring).
  Stick to the middle ring wherever possible.
• I have heard of riders removing and reversing either the chain and or the chainring. This may be worth trying but I haven't done this myself.
• Alternatively, ride a single speed! They won’t suffer chain suck as there is not enough chain to wrap around the chain ring.

a brand new quality CNC'd chainring - little chance of chainsuck (but not impossible)

a worn chainset - the granny ring is looking a little hooked and is starting to chainsuck in muddy conditions

a classic hooked chainring - this illustrates the 'shark's teeth' effect

a worn chain - evidenced by the loss of the rollers from one of the links (just above the word 'here' on the picture)

a damaged chainstay entirely due to chainsuck - open the larger picture and look at the gouges taken out of the aluminium chainstays just below the front mech

UK slop and grime - if you are suffering chainsuck during a ride, don't aggravate it and avoid these sort of trails

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