Chain drop from large to small chainring....

[Boshk]

Had this happen only 3 times so far and all 3 times its when I start any sort of uphill.
Scenario: I'm in medium to high gears on the rear cassette on flat/downhill, as I come up to hilly section, I remain in 50Front, shift down 4-6 times into lower gears. I finished the rear shifting and as I put load into the pedals, the chain slips off the front 50T chainring onto smaller 34T chainring. Each time, I've been lucky and I can press onto left thumb shifter and it engages the small 34 chainring.

Newly purchased Campy Chorus mechanical groupset
50/34 front
12-29 rear
Chorus chain...
only have 1000km on it.

any ideas?
forums say....worn out chain, worn out front chainrings.....but unless the LBS gave me 'dodgy 2nd hand' components, I can't quite see how it can be 'worn out'

I'll try video and replicate it on my trainer later.....

(also still can't get my front derailleur perfect. Keep reading on how perfect campy front derailleur shifting is.....my large to small chainring shift is flawless.....but small to large, sometimes its absolutely perfect(click click...engaged) but 30% of the time it just grinds and slips back down and can't get onto large chainring, it never slips over onto crankarm/pedals)

[Calnago]

My guess is your front derailleur is not even close to perfectly set up. Did the bike shop do it? Is the inline adjuster installed? Sounds like the high limit screw may not have been backed out when setting it up, making it impossible to get proper tension precisely where it needs to be. Lock down the high limit screw as the final step. Until then, just be careful you don't throw the chain to the outside as your moving from small to big during setup. When you're in the big ring, can you cleanly (no derailleur rub) engage all the cogs (11 thru 29)? You shouldn't have to "trim" and in fact there is no trim when in the big ring. When you shift from large ring to small ring, does it drop after one click? if so, it's definitely not set up right. That first click (when going from big to small) is no mans land when going from big to small... you need to push right through it for two clicks at which point the chain drops to the small ring and the derailleur hits a stop that prevents it from going all the way over, and thus helps prevent dropping a chain on the inside. As you move to the larger cogs, you will get a little rub on the derailleur from around the 4th or 3rd largest cog. This is normal and you then need to go the last thumb click for noise free operation on the largest cogs. Leave it in the biggest cog for the time being and do this little test. Move the left lever one click (assuming it is starting at the innermost position). You should hear a bit of noise as the chain will now be rubbing slightly on the inside of the front derailleur cage. Give the left lever one more click, you'll hear even more noise and there should be a fair amount of rub (this is really the position you would be in if you were completely cross chained small/small). Now, with the chain still on the largest cog at the back, and the front derailleur two lever clicks in (out of three down), give the lever one more click. You don't have to force it, just a positive lever click. The chain should make it's way onto the big ring if everything is adjusted right. The chain will be completely crossed (big/big) but there should be no noise from chain rub on the derailleur. You may hear a bit of noise as the teeth engage the big ring since they're coming in at a very acute angle.

I'm going to stop there. All that little test is intended to do is to see if it's even close to properly adjusted. If not, start over. I can adjust this bang on in no time without the inline adjuster. But I would never leave the inline adjuster out if I was building someone else's bike. It really sounds like a setup issue to me. You need to get it to someone who knows what they are doing.

I'm assuming a couple of things ... 1) That your chain is not too short. 2) Your chainstays are not super short (doubt it). 3) Your front derailleur cage is perfectly parallel to the chainrings (very important) and there is about 2.5mm gap between the largest teeth and the bottom edge of the outer plate of the cage.
If you're taking it to a mechanic who thinks it's the same process to set up as pre 2015 groups, then you need to find a new mechanic or tell him to call you when he's learned how to set up the 2015 stuff properly. It's time. We're in 2018 and no mechanic should be in the dark about this at this point. But unfortunately it seems, many still are.

[alcatraz]

Take several pics of your FD from different angles. Put the chain in the middle of the cassette and get some pics with it on the big+small chain.

/a

[Boshk]

My guess is your front derailleur is not even close to perfectly set up. Did the bike shop do it? Is the inline adjuster installed? Sounds like the high limit screw may not have been backed out when setting it up, making it impossible to get proper tension precisely where it needs to be. Lock down the high limit screw as the final step. Until then, just be careful you don't throw the chain to the outside as your moving from small to big during setup. When you're in the big ring, can you cleanly (no derailleur rub) engage all the cogs (11 thru 29)? You shouldn't have to "trim" and in fact there is no trim when in the big ring. When you shift from large ring to small ring, does it drop after one click? if so, it's definitely not set up right. That first click (when going from big to small) is no mans land when going from big to small... you need to push right through it for two clicks at which point the chain drops to the small ring and the derailleur hits a stop that prevents it from going all the way over, and thus helps prevent dropping a chain on the inside. As you move to the larger cogs, you will get a little rub on the derailleur from around the 4th or 3rd largest cog. This is normal and you then need to go the last thumb click for noise free operation on the largest cogs. Leave it in the biggest cog for the time being and do this little test. Move the left lever one click (assuming it is starting at the innermost position). You should hear a bit of noise as the chain will now be rubbing slightly on the inside of the front derailleur cage. Give the left lever one more click, you'll hear even more noise and there should be a fair amount of rub (this is really the position you would be in if you were completely cross chained small/small). Now, with the chain still on the largest cog at the back, and the front derailleur two lever clicks in (out of three down), give the lever one more click. You don't have to force it, just a positive lever click. The chain should make it's way onto the big ring if everything is adjusted right. The chain will be completely crossed (big/big) but there should be no noise from chain rub on the derailleur. You may hear a bit of noise as the teeth engage the big ring since they're coming in at a very acute angle.

I'm going to stop there. All that little test is intended to do is to see if it's even close to properly adjusted. If not, start over. I can adjust this bang on in no time without the inline adjuster. But I would never leave the inline adjuster out if I was building someone else's bike. It really sounds like a setup issue to me. You need to get it to someone who knows what they are doing.

I'm assuming a couple of things ... 1) That your chain is not too short. 2) Your chainstays are not super short (doubt it). 3) Your front derailleur cage is perfectly parallel to the chainrings (very important) and there is about 2.5mm gap between the largest teeth and the bottom edge of the outer plate of the cage.
If you're taking it to a mechanic who thinks it's the same process to set up as pre 2015 groups, then you need to find a new mechanic or tell him to call you when he's learned how to set up the 2015 stuff properly. It's time. We're in 2018 and no mechanic should be in the dark about this at this point. But unfortunately it seems, many still are.

Thanks Calnago, I'll try it all when I get back and to answer your question:

-Yes they did set it up
-Inline adjuster install but I think they switched out the campy one for a generic one......
The rest I can only answer when I get back home.

I initially wanted to install the groupset myself but ended up letting the shop do it. Must admit, they aren't the best, campy official mechanics are rare in Hong Kong, if any at all.

I did redo the front and rear derailleur myself when it started to be noisy, did a previous thread a while ago on the FD but still couldn't get it perfect.
Its only the last 3 rides where the chain dropped off the front chainrings, which is why I'm asking again.

Take several pics of your FD from different angles. Put the chain in the middle of the cassette and get some pics with it on the big+small chain.

/a

Hi Alcatraz, I'll post in a couple of days with the photos you want, hopefully I can get it sorted once and for all.

[Boshk]

When you shift from large ring to small ring, does it drop after one click? .......
.. Leave it in the biggest cog for the time being and do this little test. Move the left lever one click (assuming it is starting at the innermost position). You should hear a bit of noise as the chain will now be rubbing slightly on the inside of the front derailleur cage. Give the left lever one more click, you'll hear even more noise and there should be a fair amount of rub (this is really the position you would be in if you were completely cross chained small/small). Now, with the chain still on the largest cog at the back, and the front derailleur two lever clicks in (out of three down), give the lever one more click. You don't have to force it, just a positive lever click. The chain should make it's way onto the big ring if everything is adjusted right. The chain will be completely crossed (big/big) but there should be no noise from chain rub on the derailleur. You may hear a bit of noise as the teeth engage the big ring since they're coming in at a very acute angle.

I'm assuming a couple of things ... 1) That your chain is not too short.

Well update with photos and videos...

Large ring to small ring..........YES....it takes 1 click...
That test of largest rear cog on small chainring......1st click=rub, 2nd click=noisy, 3rd click=chain gets stuck between small and large chainring.......IF I 3rd click and push all the way through beyond 3rd...chain goes into large chainring.

Will redo it now and go for a ride.

"Chain is not too short" I'm wondering if it is. It does make noise as I rotate the crank, not noticeable while riding but I'm at home with no other external noise and it seems noisy. metal chain rolling onto metal chainring has to be noisy right?

https://imgur.com/B8ZJLnk
https://imgur.com/lg9aNnl
https://imgur.com/jSKBrMR
https://imgur.com/Q49Exto
https://imgur.com/TCQSuQG

and here is a video of it....
https://youtu.be/jfC15I44O-I

[alcatraz]

This could just be a big mistake but doesnt the chainset look a bit too far out from the frame? Or is it angled somehow? Are there spacers on the drive side? Maybe the right chainstay is simply very thin and I need an eye exam.

With a straight chain I think a normal chainline should have it come towards the middle of the cassette. Maybe you can verify and tell us. What cogs are you in at the back when the chain is coming off the rings going in a perfect straight line? Small/big will produce different gears obviously.

PS. I'm an amateur mechanic. Curious to learn...

/a

[silvalis]

the crank looks fine and seated properly.

[Lightweenie]

I am also relatively new to Campagnolo, but to me it sounds like increasing the cable tension by 1-2 turns of the inline adjuster should fix this...

[Boshk]

I am also relatively new to Campagnolo, but to me it sounds like increasing the cable tension by 1-2 turns of the inline adjuster should fix this...

Just did that and went for a ride, it shifts better, no more single click from large to small ring. The small to large is 90% there.
I didn't realise the cable tension could go so quick with only 900km on it.
I'll do a more through test tomorrow on it.

[dj97223]

To advise if the chain is too short, we'd have to see a pic from the side in the large cog and large chainring.

If you are still having problems, I'd suggest you start over and use the set-up video on the Campagnolo site as a guide.

[Calnago]

Ok... good... it's a setup issue for sure. And you're almost there.

Before I go on, I'm just going to insert a quote from my C60 Build thread where I outlined setting up the front derailleur so that it's dead parallel to the chainrings....

With any of the new groups these days, getting the front derailleur perfectly aligned and set is one of the most critical steps to a properly functioning drive train. Campagnolo has a special tool that helps with alignment of the front derailleur to the chain rings. I don't use it. SRAM has a guideline etched into the cage. And Shimano recommends aligning the cage to the chainrings using the same method I like to use... by taking a larger (Extra Long 8mm Allen Wrench) and with the flat edge against the teeth of the largest sprocket, it should just barely graze the edge of the outer cage plate as you rotate it along it's length. I think this is even better than using the Campy tool, since you can actually feel it grazing ever so slightly for it's entire length and thus know it's perfectly aligned. To set the front derailleur to the position where it is far enough outboard to feel the "grazing" but held firmly in one spot, I start by tightening down the front derailleur, and then before attaching any cables etc, pull out the cage and screw in the LOWER limit set screw so that it holds it firmly there, just for while I'm adjusting the alignment. Once the alignment is complete, then I unscrew the lower limit set screw so that it can settle back to it's most inboard position. Also, I like to set the cage so that it is about 2.5mm above the tallest teeth on the chain ring. I measure this by taking a 2.5mm allen key and passing it between the teeth and the cage when holding the cage directly above the teeth. When I can barely pass a 2.5mm allen key through there, but not a 3mm, I know I'm there. I set the height first, to get it positioned vertically on the derailleur tab, then loosen it off just enough to be able to swivel it a bit as I adjust the alignment. Also, note the position of the crank when doing this... the tallest teeth on the chainring are when the arm is in the 3 o'clock position, so those are the teeth you want to be referencing when setting the height...

Ok... so, in your case, as @Lightweenie said... there was not enough tension on the cable. This can be a very fine adjustment, and hence having the inline adjuster installed makes this job infinitely easier. Also, the Campy inline adjuster is the best one I've seen and works really well. A lot of others are simply garbage. If you purchased a set of Campy cables, the inline adjuster is included. Use it. Oh, and when setting that tension, make sure the outer limit screw on the front derailleur is backed off, otherwise if it isn't, it can be impossible to get the right tension on the cable as it will be butting up against that screw. Once everything is dialed in, THEN, and only then... carefully tighten the outer limit screw (when the chain is on Big ring/small cog) so that it is just close enough to the chain to prevent an overthrow. One other tip is to use just a teensy bit of purple Loctite (low strength 222) on the threads of the limit screws. Don't glob it on, but a tiny bit will keep that screw from vibrating around. Campy used to put a dab of blue threadlocker on these screws from the factory but haven't done that in quite a while. It's just good practice and will keep things perfect for a long time to come.


Re: Chain length. First of all, do not check the chain by putting it on Big/Big. If it is way too short, you risk ripping off your derailleur, but I'm sure it's not that short. In any case, check chainlength when it is on the small ring up front and the smallest cog at the back....
You can use a 10mm Allen key as a good guideline...


Campy specs that distance as (if I remember correctly) 10-15mm. I think it used to be 8-15. Anyway, it's a guide and will vary a bit depending on the particulars of your own frame geometry, chainstay length etc.. If that distance is getting closer to 20mm (the greater that distance, the tighter your chain is), I would try the next longer length instead... making that distance possibly smaller than the 10-15mm spec by a bit. As long as your chain isn't touching the metal part of the cage just above, you're good. And using this method ensures that you will be able to use the entire range of cassettes that the derailleur is spec'd for... 11/23 right on up to 12/29 (the one you're using). As an aside, Campagnolo's method is different than the Shimano's chain length setting method. Advice: Use the method advised for the group you're using, especially if you're using Shimano's newest Shadow derailleurs.

Good luck, you'll get there. What bike and what size are you working with here?

Cal

[silvalis]

the Campy inline adjuster is the best one I've seen and works really well. A lot of others are simply garbage. If you purchased a set of Campy cables, the inline adjuster is included.

Which cable set does the inline adjuster come with? I've bought a few ultra shift brake + shift kits and they didn't contain an inline adjuster.

[Calnago]

Actually, now that you bring that up... I think you're right. Perhaps they come with the complete set of ergo levers, which includes the cables and inline adjuster in one package. I'll have to check on that... good point. Maybe you just get the inline adjuster when you buy a set of 2015+ levers, yes I think that's how it works now that you mention it. So, if you have the levers, you should have the adjuster. If you don't have the 2015 or newer levers and front derailleur, you do not need this inline adjuster at all.

[Boshk]

Ok... good... it's a setup issue for sure. And you're almost there.

..
Good luck, you'll get there. What bike and what size are you working with here?

Cal

Thanks Cal

I actually followed your allen key against chainring vs FD when I first found the problems after I picked up my bike.

I'll double check everything again.
edit: 9mm between top of chain to derailleur.

Bike is a Bianchi Oltre XR3 size 50. Chorus groupset.

[Boshk]

To advise if the chain is too short, we'd have to see a pic from the side in the large cog and large chainring.

If you are still having problems, I'd suggest you start over and use the set-up video on the Campagnolo site as a guide.

Hi, I started/join a thread a couple of months ago regarding the chain length, followed quite a few videos and posted a few photos. I'll double check in a couple of days and maybe post some.
I better make sure before I start breaking pins. I did buy a new Record chain in case, current one is Chorus chain.