Chainsuck – what causes it?

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  • Chainsuck – what causes it?
  • Gooner
    Member

    i had a pace rc305 built up in feb 2008 with all XT stuff
    i have had chainsuck problems (of a varying degree) ever since
    i had the drive system changed in september but the problem is getting worse
    last night it was impossible to bike up anything steep due to chainsuck
    this was happening in the middle and granny rings
    it wont change up into the largest fron ring at all
    it is the bike i use most and the conditions are wet and muddy/gritty so what is the answer?

    jordie
    Member

    Check the rings for wear thats the first cause.

    Mackem
    Member

    The theory is that you are using a new chain on a worn chainring or vice-versa and you need to change everything. BUT, now a lot of people say that a frame has nothing to do with it but I had a PACE RC303 which chainsucked horribly no matter how new and clean everything was. So much so, i got rid of it. With hindsight i’d try sticking a spacer on the drive side bottom bracket to move everything out a wee bit, that might help, or at least help your frame.

    Premier Icon neil853
    Subscriber

    try and make sure your drivetrain is as clean as possible, a shitty drivetrain sometimes causes it.

    spesh
    Member

    If you are MTBing in the UK, shitty drivetrains sort of come as part of the package, well most of the year anyway ?

    Premier Icon scaredypants
    Subscriber

    frames don’t cause chainsuck but can be susceptible to chainsuck damage (if stay is close to rings)

    imbalance between wear on chain & rings, plus muck seem to be the main factors

    essay here, or on Sheldon’s site I suppose

    Premier Icon nickc
    Subscriber

    Officially it’s the chainring not releasing the chain at the bottom, it’s caused byy the chain getting caught on the hook formed on the teeth, so it winds back on itself, and then suddenly releases, jamming up. Some frames can cause the jamming to be worse (constant diameter stays, or big flat plates etc) but it’s not the initial cause.

    The only solution is to change the ring and chain (you may as a consequence have to change your cassette too)

    Make sure your chain’s not too long, it can also make a bad situation worse.

    Good article here

    Mackem
    Member

    I’m aware the “fact” that frames dont case chainsuck but i’ve never had a problem before or since the RC303. It just must be very sensitive.

    clydebuilt
    Member

    I have a geared inbred that suffered from chainsuck no matter what I did so I carried out brants trick with the hammer, indenting the chainstay at the appropriate spot, and hey presto, no more chainsuck. this using same chain/sprockets/lube ect, so who says frame not a significant factor…

    Premier Icon scaredypants
    Subscriber

    so who says frame not a significant factor…

    dinging the seatstay in didn’t change anything about chainsuck happening, it just stopped your frame from getting involved when the chain got “sucked”

    Bruce
    Member

    Frames might not cause chain suck but some appear to be more prone to it than others. I had a Ti Bontrager which as soon as a little wear appeared on the middle ring chain sucked with monotonous regularity. When the frame cracked and the same parts were swaped to a Litespeed the chainsuck went away except when the chainrings were very worn.

    Premier Icon igm
    Subscriber

    I am assuming the chain line is correct as that could just be adding a little extra friction into the mix – not much but check it if you haven’t, especially as it would go into big ring. My Five chain sucked for a bit but new chainrings sorted it. The titanium granny and middle are still going strong 2 years later.

    yian
    Member

    I’ve got a Stiffee (oh ur madam) with R/face atlas chain set, running granny middle and a bash ring which had this problem big time. Anyway, cured it by altering the chain line with the bottom bracket spacers. Can’t remember without going for a look, but if you have two spacers on the drive side, take one out and put it on the other side. Or if there is only one on the drive side, take the one from the non drive side and put it on the drive side.

    Worked for me which was good, as the chain had sawed half way through the chainstay.

    coffeeking
    Member

    Claiming frames don’t cause chainsuck but some are more likely to suffer from it is nonsensical. If the frame has nothing to do with chainsuck then one cannot be more susceptible than another. Assuming an all-new drivetrain, if the bike still suffers chainsuck what else can it be? I’m not claiming to know the answer, but I know that I’ve had mine suck despite all-new components. I also know that my weedier and more laterally flexible frames are more likely to suffer it so I suspect it may be something to do with an increased likelyhood of the chain being twisted and/or flexed sideways along its length, making it more likely to bind to the teeth and get sucked up in the first place. Naturally this is like changing your chainline, so chainline may also have an effect.

    My big old flexible full sus used to suffer it badly even with new components, but taking those components and putting them on my hardtail I’ve never experienced suckage yet. Though my recent solution to mucky trails and gear problems was to scrap them all 🙂

    Premier Icon nickc
    Subscriber

    some bikes suffer more because not all frames are designed the same. As the chain sucks (gets stuck at the bottom of the chainring, and won’t drop off) the chain can’t be either jammed because of the frame design, i.e. there’s lots of space and the stays are out of the way, or it gets stuck.

    coffeeking
    Member

    nickc, thats the after effects of chainsuck, some frames just dont suffer the suck in the first place. Its easy as pie to tell when you’re suffering chainsuck even when the chain doesnt get anywhere near your frame (I only have one frame where it actually contacts the frame when suck occurs).

    Premier Icon igm
    Subscriber

    Coffeking – chainline?

    Premier Icon Ogg
    Subscriber

    A mates bike suffered chain suck and most of the problem was down to a slightly bent mech hanger and knackered jockey wheels (lots of mud and a wide rear tyre dumping said mud on chain didn’t help…)

    coffeeking
    Member

    igm – I always try to keep the same chainline between frames, I have so many BB’s (square taper) its beginning to get stupid (I have a box with about 15 in!). So naturally I’ve always tried to negate the chainline issue, but when you stomp on the pedals if your frame twists (as mine does, so much so that my rear wheel catches in the worst suck-affected frame, but doesnt in the full sus despite having the same clearance) then your effective chainline will be to pot anyway. Thats why I think frame stiffness plays a large part.

    PJay
    Member

    Odd as it might sound I actually found a change of lube helped my chainsuck significantly. For a while I tried Finishline Pro-Road which was supposedly good for mountain bikes too and meant to sit somewhere between a dry and wet lube, it was unbelievably mucky and I was getting chainsuck (my 853 Inbred has very tight big ring/chainstay clearance and the chain was riding up the middle ring and then getting ripped up between the big ring and chainstay). Going back to my old lube made a huge difference! I’ve also switched the aluminium granny and inner rings on my XT chainset to Deore steel rings which also seems to make a difference.

    I don’t know whether a frame design can be more susciptible to chainsuck than another, but some are certainly more susceptible to damage once it occurs.

    coffeeking
    Member

    Here’s a fairly interesting link

    As usual you can pull holes in their methods, but its seems fairly robust, though I dont see mention of changing from one bike to another, or trying all new drivetrain on two differently compliant frames.

    Premier Icon igm
    Subscriber

    coffeeking – fair point on flexy frames and chainline

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