Had my 2010 Stumpjumper fsr frame (alu) replaced with the carbon one under warranty and have had quite a lot of chainsuck issues with it from the start.

I’d swapped out the original chainset on the alu one for my XT one and it was running fine. It’s a fair age, but to me the ‘rings don’t look too worn. I had no issues with chainsuck on the alu frame with this chainset.
The frame was swapped for the carbon one and at the D2D in very muddy conditions I had stupid amounts of chainsuck that has made a real mess of the chainstay.
I put it down to the awful conditions and haven’t really had the issue since (only once going up that steep concrete slope at Cwm Carn)…..

I replaced the chain a few weeks ago as the old one was shot. Shifting with the new chain is fine.
I went to Chicksands last week and up the steep bits of the XC loop I was getting really bad chainsuck again.

It only seems to happen in the granny ring and you can hear it when it’s going to happen.
I have bought a new 22t chainring to fit this evening, but should there be anything else I look for??

The frame has push-fit bearings and as far as I can tell I can’t alter the chainline (with spacers, like HTII), as a result. I wonder whether the XT chainset is compatible with this style BB assembly?? I assume it is.

If I still get it with the new ‘ring then it’ll be back to the shop to probe their collective mind.
I intend to botch together some kind of inner tube/zip tie guard this evening as the chainstay is looking like it’s been given a right mauling….

in your position i’d be replacing the granny ring before going any further. Mine didn’t look worn at all, but replacing it fixed my chainsuck

edit: can’t read, derp.

was going to suggest one of these;

http://www.bikerumor.com/2010/09/03/tomac-k-edge-release-most-technogically-advanced-anti-chainsuck-device-ever/

but not sure it’ll work with a press fit BB.

I’d do what you’r eproposing – go to dealer and see what they say – maybe have a look at some other bieks the same and see if the set up is any different?

retro83 – that’s what I thought. Sounds encouraging too, so I hope that solves the problem!! Fitting it tonight, trying it out on Sat.

wwaswas – yeah, I remember seeing that chainsuck jobbie but couldn’t find it again. And yeah – I think the press fit BB is going to be a pain, as most chainsuck devices I’ve seen replace a spacer on the BB.

Problem with comparing with other bikes – I haven’t seen another carbon one of these anywhere and the alu ones just have HTII BBs instead of push fit.
If the new chainring doesn’t solve it, then I’ll be back to the dealer & see what they propose. It’s a real pain when you’re struggling up a steep climb & all of a sudden there’s a graunch followed by locked cranks….

if you’ve fitted a new chain and chainring I’d seriously consider a new cassette as well.

New granny ring and you’ll be fine.

Is the rear mech in good order and fitted correctly ? If not then it may no be putting enough tension on the chain and this may be the cause of the chain suck. Chain length may also be worth checking.

wwaswas – Member
if you’ve fitted a new chain and chainring I’d seriously consider a new cassette as well.

Why’s that? Shifting seems fine. Can the condition of the cassette affect chainsuck? I thought a cassette should be good for a couple, if not 3 cassettes? The XT chainset came from my previous bike (to replace the cheapo one that Spesh fitted), so it’s had a lot more wear than has occurred while fitted to this frame.

MarkN – it’s an XTR Shadow and only a yr old, doesn’t appear to be mis-aligned and shifts OK, but I will give it the once over. Tension is fixed by the spring inside the cage, isn’t it? It’s not something I could adjust?

Chain length – would too long or too short cause it to suck? I am guessing too long from your query about tension in the rear mech perhaps not being enough.
I replaced the chain and copied the length of the old one, so it could be an issue.

I think plan of action is:

– fit new inner chainring, protect chainstay & give rear mech the once over. Should be able to do this tonight.
– Ride & assess.
– Check chain length, even if the above cures the problem, just so I ‘know’ it’s correct.

Cool! Getting some great advice! Thanks.

was workign int he assumption that if the chain and chainring were ‘shot’ that the cassette was probably similarly worn.

It’s something I’d consider doing next if the problem isn’t solved.

wwaswas – yeah, will perhaps look into that if new chainring, checking mech and checking chain length don’t solve it.

I am really hoping that it’s just the chainring, as I can’t be doing with all the faffing about.
Having just moved house, in some people’s eyes (the other half) time spent in the garage ‘tinkering’ could be spent doing much more ‘important’ things like putting up curtains, looking at wallpaper swatches, deciding how to lay out the living room etc.

And I’ve got a tubeless front wheel that after staying inflated for 9 months, has suddenly deflated while not even being ridden…..! That needs looking at too….Bah!

Everytime I’ve suffered from chainsuck, replacing the granny ring fixed it.

Looking closely at the teeth on the granny ring i could tell they were worn, but maybe if you dont know what you;re looking for it might look alright to you.

Update for those interested:

I changed the chainring Thursday night, and following two laps of Cwmcarn on Saturday I had not one instance of chainsuck – even with some purposefully hamfisted shifting to try & induce it.

Initially there was occasional chain skipping that seemed to be be coming from the cassette (new chain recently fitted), but this went after about 20 mins.
Not a conclusive test as it was mainly dry & the rain on the second lap didn’t exactly turn it into a sludge-fest, but initial impressions are encouraging…..

I compared the old and new ring and there was barely any difference in the tooth profile….must be a very subtle change that takes it from working OK to not working…..