# Chain falling between chainrings



## AtBothEnds (Sep 8, 2010)

Hi forum,

I'm having some trouble when shifting between my chainrings, sometimes when shifting from the small to large ring or vice versa the chain will fall between the two rings. It's not jamming and locking up my drivetrain but I do end up frantically spinning my cranks until I can shift out or have to stop to fix it with my fingers. Most of the time this happens when I'm shifting down from my large to small ring.

My setup is a stock 2007 Felt Z65. I picked it up new last year from a shop and have maybe only put about 800KM on it. 

Here's some info on the components if this helps at all: 
Component Group:	Shimano Ultegra
Shift Levers:	Shimano Ultegra
Front Derailleur:	Shimano Ultegra
Rear Derailleur:	Shimano Dura-Ace
Crankset:	FSA Team Issue Carbon, 36/50 teeth
Rear Cogs:	10-speed, 11 - 25 teeth
Chain:	Shimano 10 Speed

Everything on the bike (from a quick visual inspection) seems aligned and in good condition.

I've cruised around the internet for info but can't come up with a whole lot. 
Most of the info I've found about this problem relates to a new chain that is too narrow or one of the rings being machined poorly.

It could be just a case of the front derailleur needing adjustment but I haven't found any adjustment specific to this problem and I'm hesitant to mess with the derailleur seeing as this problem doesn't happen all the time. I don't want to make the issue worse than it is or create new problems for myself seeing as I'm fairly inexperienced in the wrenching department.

If anyone could offer any advice it would be appreciated.

Thanks


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## wibly wobly (Apr 23, 2009)

You might have a 9 speed inner ring. The spacing in different for 9 and 10 and it can fall between them depending on what gear you're in. I had this problem when I upgraded my 7700 to 7800 shifters before I changed the inner ring to a 10 speed. Hasn't been a problem since. It should be marked if it's a 10 speed inner.


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## AtBothEnds (Sep 8, 2010)

The only info I can find on the small chainring says "FSA 36T 110mm BCD" on the outside and "wb078/36t/6a/c" on the inside. Do you think I'd have a 9 speed inner ring that comes stock on a 10 speed bike? That seems strange to me.


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## wibly wobly (Apr 23, 2009)

No idea about the marking for FSA rings (just had a look on their site and didn't see anything) but, my Shinamo inners are marked 10 speed. I seem to remember hearing something about FSA rings that are 9/10 speed are a bit crappy but, the 10 speed rings are ok. This is going off something I "think" I heard. I may be totally full of it. I can't say. Someone else will have to chime in. This may not be your problem but, it's the first thing that comes to mind. If the bike is second hand, it may have been changed with the wrong / bad ring. 

I know I had problems going from the big to little ring skating if I was too high up on the rear cassette. It was pretty sketchy at times. I had to be careful when I dumped the chain and never did it standing just in case. Otherwise, you're likely to have a tumble. I think Leonard Zinn has a thing about this effect talking about upgrading 9 speed drivetrain to 10 speed. Can't find it though. He said it's pretty rare.


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## PJ352 (Dec 5, 2007)

You don't say if the bike always shifted this way or if it's a fairly recent occurance, but if its never been back to the LBS for tuning/ adjustments, given the mileage it may be time to do so. Might just be a simple FD/ cable adjustment.

I'm not familiar with FSA's, but FWIW if Shimano inner rings are reversed the result is the shifting you describe, so you might want to check that your ring is oriented properly.


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## Opus51569 (Jul 21, 2009)

Strange considering everything is stock on the bike. I had a similar issue when I swapped a 50t outer ring for a 46t. The chain would drop between the rings when shifting from large to small. The solution I ended up using was to install some 1/64 inch washers on the chainring bolts. This adjusted the spacing between the rings just enough to solve the problem. I don't know if it would work in your case, though.


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## wibly wobly (Apr 23, 2009)

My issues only arrived when I switched my 7700 drivetrain to 10 speed. The rings were 9 speed at the time and they didn't like the narrower 10 speed chain. I put on a 10 speed 39 inner and it went away. I did have intermittent problems like you're describing but, only when I dumped the chain when I was around the middle of the cassette or higher. Like I said, this may not be your problem but, it's the first thing that came to mind.


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## Kuma601 (Jan 22, 2004)

As PJ352 mentioned. Check your FD alignment so that it is placed properly in relation the the big ring and such. Then verify cable tension. Might also check the chain ring nuts to insure they are torqued properly. Certain gear combo's might lend to this erratic shifting so not dumping the chain in that gear is also a possible solution. In past discussions, I've read about poor shifting FSA rings.If you think it is adjusted properly, you might try Shimano rings. 

I have a Shimano 600EX 6spd crankset with a 42T, 6spd inner and 6500 52T 9spd outer ring. Though the 6spd inner ring is offset about 1.5mm wider than current 9-10 spd rings, it drops down nicely. The 6600 equipped bike is using a 40T inner ring from the 6spd days, no problems for me. YMMV...


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## AtBothEnds (Sep 8, 2010)

Hey everyone,

Thanks for the advice. 


Wibly Wobly: I’ll look into the 9/10 speed chainrings. I didn’t know that FSA would have one for both; I just assumed they’d make a dedicated 10 and a dedicated 9. I couldn’t dig up anything on the internet in FSA crankset searches I did before my initial post but I’ll look harder and maybe come up with some answers there.

As far as the skating issue you’ve had, it’s not really the same as mine.  My shifts are either fairly smooth or they drop into the gap between the rings. There can be some skating when shifting from the small to large but usually when I’m cranking too hard.

PJ352: I’ve had the problem from the start but back then I just thought it was a few freak occurrences, now I see that it happens enough that there is an actual issue. I’d take it back to the LBS but I bought the bike in a different city. I’m just hoping this is something I can fix at home, I’ve ignored because I don’t use the small chainring very often as I live in a pretty flat area. 
The ring doesn’t seem to be reversed but I only assume that because the FSA logos on both chainrings face outward.

Opus51569: About installing the washers, wouldn’t that just widen the gap and maybe make my problem worse? In my head I could be picturing something different from what you’ve done.

Kuma601: I’ll go through the FD to see if there’s anything I can fix/adjust. I was hoping somebody could come up with a quick “Oh, this is the issue…” instead of me having to go through the entire FD setup. I’ll pay more attention to the gear combos next time this happens, it’s not something I’ve thought about.
Everything looks in order from a visual inspection but maybe the problem can’t be seen as easily as I’d like. I’d rather not have to buy new chainrings if I don’t have to.


I’ll go through the FD setup and get back to everyone. Thanks for the help.


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## Opus51569 (Jul 21, 2009)

It does seem counterintuitive, but I think in my case the chain would hit the tops of the ring teeth. That extra bit of space changed the alignment and the timing of the shift just enough to allow the chain to engage the ring the way it should.


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## seppo17 (Dec 7, 2008)

Small chain ring on backwards?


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## campybk (Oct 20, 2002)

I have dealt with this on two friend's bikes and both times it was the inner ring installed backwards. I see that you said that you can see the FSA logo facing out on both rings, but maybe the inner ring was labeled on the wrong side at the factory. Remove one of the mounting bolts and see if the inner ring has a recess for the nut. If there is no recess, it is on backwards. Good luck. Disclaimer: I have never touched a FSA set of rings, but imagine they are similar in build to Shimano and Campy. Good luck.


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## AtBothEnds (Sep 8, 2010)

I've been out for one ride and it didn't seem to get much better even though I've spent a bunch of time working on both derailleurs. I just spent a bunch more time tonight and am going for another ride tomorrow, hopefully it'll be OK this time. 

I checked the small chain ring for the recessed spot and found it so that (hopefully) takes care of that as far as being the issue.

If I can't get this figured out I'm probably just going to give up and go to a shop. I'm starting to wonder if the FD has a slight bend/twist that I can't see but is just enough to kick the chain in a funny direction.


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## AndrwSwitch (May 28, 2009)

I had a supposedly nice FSA ring in the middle position on my mountain bike for a little while. I could practically see that thing melting - wear was incredibly fast. If it's a new problem, especially if it developed over time, it could be that - the teeth are getting thinner, so the space between the outer face of the teeth on the inner ring and the inner face of the outer ring is effectively bigger, just enough to fit your chain.

I'm a bit of a Shimano fanboy. If you can swing it, I think just sticking the matching Ultegra crank on your bike would solve the problem - their rings rock, but don't always play well with others' cranks.


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## krugaire (Jul 1, 2011)

Did you change your chainrings??? If you did, you might not have the chainrings on the right position on the cranks. One of the chainrings has a pin, that should be lined up with something to stop the chanin from fall in down in there. Post #3


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## AtBothEnds (Sep 8, 2010)

AndrwSwitch: The thought has crossed my mind that the chain rings need to be replaced and there is some wear but not enough (at least I assume) to warrant getting a new crankset. I don't think the problem has become worse over time, when it was first happening I thought of it as a few freak occurrences but looking back I notice that it's a little more frequent than that.

Krugaire: I haven't changed out any parts or taken anything apart and put it back together. There is a pin on the large chain ring that is lined up with the drive side crank but that is to prevent the chain from falling between the crank and the chain ring, the other side of the large chain ring and the small chain ring have no pins.


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## dgeesaman (Jun 9, 2010)

seppo17 said:


> Small chain ring on backwards?


^^ This will cause the problem. Not sure about FSA, but on Shimano the chainring bolts have a recessed head and the inner chainring will have matching recesses on only one side. Very easy to get backwards if you're not paying attention.


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## farva (Jun 24, 2005)

I had the same problem with my FSA gossamer cranks. They chain fell into "no mans land" when dropping from big to little ring. Nothing to do with 9 vs 10 speed. Turns out the big & little ring need to be a matched set. Check for 50/34 or 50/36 markings on the big ring. The combo should match. When I called FSA about it they sent me a new small ring. Works OK now


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## AtBothEnds (Sep 8, 2010)

farva said:


> I had the same problem with my FSA gossamer cranks. They chain fell into "no mans land" when dropping from big to little ring. Nothing to do with 9 vs 10 speed. Turns out the big & little ring need to be a matched set. Check for 50/34 or 50/36 markings on the big ring. The combo should match. When I called FSA about it they sent me a new small ring. Works OK now


I have "50/36" on the big ring and "36T" on the small ring, both are also stamped "110mm BCD." By this I assume they are matched. Man, a lightbulb went off in my head after I read your post and was thinking I finally found the problem. Thanks for your help anyway.


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## farva (Jun 24, 2005)

Well that sounds right then. Is the little index mark on the small ring aligned with the crank arm? Long shot but worth checking. When I called FSA about it they sent me a new set of chainrings, somewhat eluding to some "defective" ones out there. Maybe yours are in that batch? I'd call them & see what they say. Good luck


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## wibly wobly (Apr 23, 2009)

If it's not an issue with chain width then it has to be something to do with the rings. If it's a part mismatch, then maybe that could be it. I'd like to find out what the end result of this is whatever it is.


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## AtBothEnds (Sep 8, 2010)

wibly wobly said:


> If it's not an issue with chain width then it has to be something to do with the rings. If it's a part mismatch, then maybe that could be it. I'd like to find out what the end result of this is whatever it is.


I'll keep everyone updated, I'm going to chat with FSA soon and maybe they can point me in the right direction. If that doesn't go anywhere I'll likely take it to a shop to see what they think.


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## AtBothEnds (Sep 8, 2010)

I talked to FSA today and they told me that the 50/36 combo has been an issue. All the parts I have are correct but the guy told me that they realized after having that combo out for a while that 36 was too many teeth for the inside. Derailleurs were sometimes having problems getting the chain on that size of ring so they went to 34 teeth with later editions. Though I didn't ask him directly about FSA sending me a new ring as a replacement because they know of the problem he did tell me that I had to go find a 34T. I should have pressed him a little on that seeing as it's a known issue but, at the same time, this is a 4 year old bike.


Edit: Dumb question but can I put any company's 34T on the crankset or do I need to stay with FSA? Even if I'm able to put another company's chain ring on the crankset is it a good idea or will mixing the parts (two chain rings from two different companies) potentially lead to further shifting problems? I'm even a little tempted to switch out both chain rings for 105 or Ultegra but keep the FSA cranks.


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