Chain sticks on chainring

[ib1]

Hi,

My front mech has broken because the chain kept riding up the chain ring and jamming in the front derailleur .So I thought I'd ask here if anyone has had this problem and if so did they find a solution .
To be more specific ,what happens occasionally , is as I'm peddling the chain that usually disengages from the chain ring stick's onto the chainring, almost doubling up until it meets the front derailleur .It's happened on several occasions and bends the front derailleur.It has now snapped and needs replacing .

At first I thought it may be down to too much muck and oil on the chain and or chain ring ,though it happens even when relatively clean .Or Maybe a damaged tooth on the chain ring, though I can't find one that looks damaged . Any Ideas so as to save the new derailleur I've just ordered ?

Oh yes my ride is a Broadman cx team cyclocross

Chainset: FSA Gossamer compact BB30

 

[Globalti]

Check the chain for a stiff link.

 

[ib1]

Check the chain for a stiff link.

Ok will do thanks . If I find a stiff one will I have to replace it or is their a method to loosen it?

 

[Hawk]

Ok will do thanks . If I find a stiff one will I have to replace it or is their a method to loosen it?

View: http://www.youtube.com/watch?v=QU79CQsz-Ps


To emphasise what he said, make sure the pin at the stiff link isn't sticking out one side of your chain.

Other stuff to check: chain wear, cassette wear, chainring wear. Try googling all of those if unsure. The chain wear can be measured with a ruler and the other two checks just visual inspections.

Is your chain clear of your derailleur when you're in gear? If not, you might need to do some gear adjustment.

Alternatively, are you "crossing" your chain too much? If you are using, say, the big chainring on the front (rightmost) and the big chainring on the back (leftmost) then pedalling will create a force that wants to slide your chain off your chainring in a way it wasn't designed to do.

Are the bolts holding the chainrings tight? http://www.pezcyclingnews.com/photos/tech/Tiso/tisofsa.jpg - the red bits on that set up are the bolts. If you have a triple chainring (three at the front) you'll also have some on the frame-side of the chainrings that hold the lowest chainring to the pedal assembly

Finally, have you replaced the chainring yourself etc? It's possible that one's on the wrong way, thus making the gap between your front chainrings bigger than it should be.

 

[Garz]

If memory serves theres two reasons why this happened on my boardman comp.

1. Poor setup
2. Not holding the shifter long enough to engage the change

I fixed 1. after I set the bike up myself (from receiving it from the shop). Like you it did however bend the front mech enough to warrant a tinker session. It took a long time for that to happen again, I probed a cycle mechanic whom lives a few doors down and he referred to 2. So basically dont just tap the shifter lazily expecting a crisp change, you can hear it complete a good shift when you get used to analysing it. This was on a shimano 105 FD.

 

[ColinJ]

It sounds like chain-suck to me.

 

[ib1]

Yup chain suck it is

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.

Thanks for the help guys .I'm investigating & will post back when I find out what is causing this mechanical deviation from the operational norm .

Update:

Chain links ok.
Chain-ring teeth ok

 

[e-rider]

chainsuck - get a new chainring

 

[woohoo]

I agree with the likely causes suggested but ..... I had something similar happen on a new MTB and checked the usual stuff like chain for stiff links and so on. Everything seemed fine so I tried increasing the tension at the rear derailleur by adjusting the "B" screw and the problem disappeared, never to return.

 

[Hawk]

I agree with the likely causes suggested but ..... I had something similar happen on a new MTB and checked the usual stuff like chain for stiff links and so on. Everything seemed fine so I tried increasing the tension at the rear derailleur by adjusting the "B" screw and the problem disappeared, never to return.

This helped me too! Also, shortening your chain might help - verify it's the right length (google)

 

[tyred]

Carefully check the chainring in question for a bent tooth or burs. Ideally you would replace but sometimes you can correct the damage, especially if it's a steel ring.