Chain dropping problem.

Cee-Jay-Cee

Out for a spin today and twice while on the big ring the chain came off at the front of the ring (nearest the front wheel) however remained on the top of the ring. I wasn't shifting it at the time and didn't hit any bump in the road which would throw the chain so I'm wondering if a stiff link on the chain would cause such a problem?

The first time it happened I had to stop and physically put the chain back on the big ring. The second time it happened I back pedalled slightly which realigned the chain on the big ring

Orion

How many km on it? Could be stretched and need a new chain.

wirelessdude01

Could also be that a link is about to break. Had this during the week.

Cee-Jay-Cee

There is approx 3k on the chain which is Ultegra/6800. I would have hoped to get more than 3k from it!

I done 90km today and was on the big ring for 90% of it.

The drivetrain was quiet and I asked my mate to cycle behind and try and see if there was anything unusual looking about the chain but he said it looked fine with no buckles or kinks while turning.

I'll take the chain and cassette off and clean both thoroughly and re-lube them and check each link and take it from there. Will Also check it for stretching.

Wishbone Ash

Is the big ring worn? (Shark fin teeth?)

Cee-Jay-Cee

Wishbone Ash wrote: »

Is the big ring worn? (Shark fin teeth?)

No they're still like new with little or no signs of wear.

cython

Couple of ideas you could try to see is there a dodgy link:

1. With the bike in a stand, or even just propped up, turn the cranks backwards, and see is there any part of hte chain that when passing through the mech causes it to "kick" or jerk - that could indicate a stiff or otherwise troublesome link

2. (and this one might seem a bit out there, but it flagged an issue for me before!) If you have the chance to clean down your drivetrain, then do the same as above after cleaning it, but run the chain through a cloth or rag, with light pressure on the sides of the chain. If the cloth snags somewhere, it may also highlight a problem. I had a case on the OH's winter bike whereby one of the outer link plates link had popped off the end of a pin, and she had been complaining about the shifting (on the rear, mind you), but it was when the loose plate kept pulling the cloth out of my hand that I saw exactly why.

In any case, both of the above have a chance at highlighting potential "deformities" in the chain, so may be worth trying.

Cee-Jay-Cee

Checked for wear a while ago and it's worn, the checker doesn't fall fully into the link but about half way compared to the new chain on my winter bike so new chain needed shortly which is very disappointing. I would have expected more than 3k kms from an Ultegra chain!

Currently Dura Ace 9000 chains are cheaper than 6800 chains on CRC. Are they worth it over Ultegra? I'd rather pay extra and get longer from a chain.

smacl

Just a guess, but it could be that if you spend a lot of time in the big ring you're putting more power down than if you were spinning faster in a lower gear which in turn translates into shorted chain life.

koutoubia

I honestly wouldn't expect more then 3000km out of a chain. If you do you are only starting to 'mate ' the chain with the cassette.
You may have trouble with the new chain and old cassette.
I run 3 chains in rotation. Swap at 1000km from chain 1 to chain 2 then chain 2 to 3 after another 1000km then back to chain 1. Chains are cheaper then cassette's!

Oh and get KMC 11sp chains. Really good chains.

Cee-Jay-Cee

The chain is only worn 50%, if I change it now it'll probably prolong the life of the cassette which is the same age/mileage as the chain?

I was considering a kmc chain as I've always had kmc chains on my winter bike albeit the cheapest ones available. Which 11spd kmc is recommended?

koutoubia

Aarrgh I only threw out the packaging of the last chain yesterday. I think it's the one on CRC for about 30-35 euros. Never had an issue with them .
WRT to your other chain maybe hold onto it as an emergency chain.

Cee-Jay-Cee

CRC and wiggle both out of the X11 SL Chain so ordered one from Bike24. I'll clean and lube my own up to do in the meantime.

That was the first and last Shimano chain I'll own. I'll stick with kmc from now on. I got over 7000km from the last kmc chain on my winter bike which was only cleaned half as regularly and was used predominantly in wet crappy weather.

Cee-Jay-Cee

I removed the chain and cassette last night and cleaned both of them in white spirits and re-lubed them. Also cleaned jockey wheels and chain rings and front and rear derailleurs. Re-fitted everything and re-indexed the gears (they were out slightly for some reason) Anyway I can induce the chain drop while cross chaining on the big ring (front and rear) and back pedalling slightly.

I do have a habit of cross chaining especially when dropping to the small ring is more a hinderance as the hill/incline is only minor and can be easily managed in the big/big combo and I get no chain chatter when doing so, so sometimes I end up doing it without realising. I guess that too is a reason for the chain stretching within 3k kms. I'm not sure that if the chain dropping while back pedalling ever happened before though but its possible the chain reacts that way now that its slightly stretched.

Cee-Jay-Cee

Thought I'd update this. I fitted a new KMC EX chain and still have the same problem, ie when in the big/big combo and back peddling, the chain comes off the big ring. I marked the chain ring and went through the gears and back to big big combo and it comes off in the exact same positions at the little flat peg things around the outside of the big chain ring. Are they the chain pick up Points?

I know I shouldn't be cross chaining but that's not really the point, the chain shouldn't come off like it does. I have a sneaking suspicion it's absent rear derailleur However wouldn't that cause other problems shifting as there are none and it shifts perfectly through all gears.

Going to drop it into LBS on Monday and see if they can figure it out unless someone has any idea of something I could try in the mean time.

Eamonnator

Could it be, that your front mech needs to be adjusted slightly, not up or down, but rather rotated a bit.

koutoubia

So its coming off the big-big combo when pedalling forward and pedalling backward!
I think your chain line isnt able to cope with the big - big scenario but if you want to use this combo adjust your fd so when you are in that combo the inner plate of the fd is clearing the chain by the smallest amount or even just brushing it so it will keep the chain on. You have a avery slightly worn or damaged tooth that is letting the chain 'go' when its in that position.


I have the very same problem but its on the 39-11 (small-small).
Because the chainline is so extreme it jumps onto the 53.

Cee-Jay-Cee

koutoubia wrote: »

So its coming off the big-big combo when pedalling forward and pedalling backward!
I think your chain line isnt able to cope with the big - big scenario but if you want to use this combo adjust your fd so when you are in that combo the inner plate of the fd is clearing the chain by the smallest amount or even just brushing it so it will keep the chain on. You have a avery slightly worn or damaged tooth that is letting the chain 'go' when its in that position.


I have the very same problem but its on the 39-11 (small-small).
Because the chainline is so extreme it jumps onto the 53.

No it's fine when pedalling normal (forward) it only happens if you back pedal. I discovered it when in the big/big and was freewheeling and was rotating the pedals backwards To go around a bend.

I don't think it's the front mech as the chain starts to come off at 6 o clock position and not the top.

cdaly_

Don't cross-chain. Drop to the small ring earlier instead.

07Lapierre

OP. In my opinion there is nothing wrong with your bike! All chains will drop onto a smaller sprocket as you describe. It only happens when on the big ring/big sprocket?? A bike drivetrain is not designed to work if you pedal backwards.

If you back pedal on a new bike, it may not happen, but that's because the chain and cassette are new...do 100k on the bike and it will.

Just don't pedal backwards..problem solved.

Cee-Jay-Cee

cdaly_ wrote: »

Don't cross-chain. Drop to the small ring earlier instead.

That's all and well however the chain should not drop off the big ring and onto the BB no matter what gear combo I'm in. It's happening now while on the second biggest sprocket on the rear too.

I was out for a spin yesterday and staying out of the big/big gears purposely but did use the second biggest cog and while stopped at a junction I pedalled back half a revolution to line up the pedal in order take off and the chain fell off the big chain ring. That should not happen.

martyc5674

Been following this thread...
My first port of call would be the rear derailleur, it is what guides the chain onto the cassette(top jockey wheel)...and collects it from the bottom of the front chainring(bottom jockey wheel)

The bottom jockey wheel should have a little play/float in it to allow it to "twist" towards the front chainring.

You mentioned your rear derailleur needed indexing??...Any chance it took a slight knock?(and is now not able to point from big ring to big ring without straining the chain?)

Also worth checking the springs in your rear derailleur are tensioning the chain correctly/adequately.

Also I would check that your chain is long enough so that the bottom chain line is not too "taught" when selecting the big/big combo(you should be able to double over the chain on itself when in this combo...see sheldon for a better description if your not familiar with it...basically you add an extra inner and outer link to minimum required chain length).
The reason i suggest this is that too taught a bottom chain line will interfere with the bottom jockey wheels ability to twist towards the front chainring)

Marty.

Cee-Jay-Cee

I dropped the bike into LBS for them to have a look at it and see if anything amiss. I did point out that I felt it was an issue/problem with the RD.

In regard to chain length, the new chain has the same number of links as the old one so I don't think there's a problem there. If the LBS cant sort the problem I might add in an extra link and see if it makes any difference to it but hopefully they'll sort it and I wont have any further problems with it.

Cee-Jay-Cee

FINAL UPDATE:

As mentioned above, I bought a new KMC chain and split it and removed links to leave it the same length as the Ultegra chain i removed and the problem still existed and was in fact worse as the chain was dropping off the big ring in the 28T and 25T sprockets. Got pissed off and left it into LBS to sort which they duly did. The problem: The chain was 2 links too short!!! The previous chain was fitted by another LBS when I had the groupset fitted and so I assumed it was the correct length and in fairness it worked flawlessly for 18 months! Anyway as the kmc pins can't be re-used I told them to go ahead and fit a new chain. So new 6800 chain fitted and gears changing flawlessly again in all gear combo's and the best part was it only cost me €35 which is cheaper than Wiggle (by €1 and €5 cheaper than CRC!!)!

On a side note...Ultegra 6800 chains are quieter than KMC.