Chain keeps falling off little ring

[jsull14]

Hi. I have a 105 triple and lately my chain has been falling off on the inside of the little ring when I downshift on a climb. This puts me in panic mode as I scramble furiously to unclip before I tip over.

I have been turning the screws a bit on the front derailer to try to improve the shifting performance overall on the front rings and I may have messed something up.

Is there something I should be looking for, such as the distance between the chain and the FD? Is there a common reason why a chain falls off?

Thanks for any help.

 

[PeterF]

Hi. I have a 105 triple and lately my chain has been falling off on the inside of the little ring when I downshift on a climb. This puts me in panic mode as I scramble furiously to unclip before I tip over.

I have been turning the screws a bit on the front derailer to try to improve the shifting performance overall on the front rings and I may have messed something up.

Is there something I should be looking for, such as the distance between the chain and the FD? Is there a common reason why a chain falls off?

Thanks for any help.

Most likely you need to adjust the inside limit screw. If you release the front derailler level to the inside and it is throwing the cage to far inward, that might be why the chain is dropping. It's a pretty easy adjustment.

 

[Phill P]

My girlfriends relatively new ultegra doube set keeps doing the same going from the big to smal ring. We've had it serviced, and it got better for a while, but then it did it again the other day. Of course it always happens when approaching a climb so very annoying.

I haven't checked but I'm beating the limit screw it very loose and wiggling itself out allowing the chain to throw to far pushing too hard throwing it off. Very annoying, guess it will need some mild lock tight.

Had the same problem on my campy triple. Only solution is to adjust the limit so you can only just get it down into the small ring. The chain lines on road triples seem to be such that if in the wrong gearing the chain quickly pulls to far inboard and misses the teeth on the granny and drops off.

 

[mikesbytes]

Probably the adjusting screw.

Could also be a bent tooth or a bad chain link

 

[wiredued]

If your granny is really small Sheldon Brown recommends the third eye chain watcher. I bought one when I changed from 30 to 24 teeth. I forget where I got mine but REI sells them.
http://www.rei.com/product/9610812.htm

Here is some derailer adjustment stuff too
http://sheldonbrown.com/derailer-adjustment.html

 

[alfeng]

Hi. I have a 105 triple and lately my chain has been falling off on the inside of the little ring when I downshift on a climb.

By chance, did you recently change your chain?

If so, is your drivetrain an 8-speed 105?

If so, then you may have the wrong width chain (I know a LOT of people don't think it makes a difference, but it truly does; particularly, with a triple) ...

If you are running an 8-speed Shimano triple, then you want a Shimano chain which PROBABLY has a numerical designation that ends with a '0'/zero -- e.g., IG-70 rather than HG-73.

 

[artemidorus]

When I installed a removable chain link to my 7spd chain, it started falling off the granny ring during random downshifts, frequently. I discovered that I had installed the link upside down; turning it over solved the problem. Adjusting the lower limit did not help the problem other than by locking out the granny ring.

 

[vchu7105]

I had simmilar troubles with chain drops and gear shifting when i first purchased my bike. Make sure your mechanic knows what he is doing: shop around and look for an adult mechanic who has had years of experience with bikes. If a kid built your bike or even some bike shop owners, they are not mechanics!

When I installed a removable chain link to my 7spd chain, it started falling off the granny ring during random downshifts, frequently. I discovered that I had installed the link upside down; turning it over solved the problem. Adjusting the lower limit did not help the problem other than by locking out the granny ring.

 

[jsull14]

Thanks for the help. I am getting closer to figuring it out. Sheldon also has good explanations. I am going to buy a lightweight philips screwdriver to carry with me.

My chain and drivetrain are stock that came on the bike. It's a 2006 Specialized Roubaix with 105/Ultegra mix (RD is the only piece of Ultegra)

9 speed with 30/42/52 rings.

By chance, did you recently change your chain?

If so, is your drivetrain an 8-speed 105?

If so, then you may have the wrong width chain (I know a LOT of people don't think it makes a difference, but it truly does; particularly, with a triple) ...

If you are running an 8-speed Shimano triple, then you want a Shimano chain which PROBABLY has a numerical designation that ends with a '0'/zero -- e.g., IG-70 rather than HG-73.

 

[artmichalek]

How long have you had the bike? New cables take a bit of time to fully stretch out, and too much slack can cause overshifting.

 

[RickF]

Thanks for the help. I am getting closer to figuring it out. Sheldon also has good explanations. I am going to buy a lightweight philips screwdriver to carry with me.

You should not need to carry a Phillips screwdriver to adjust the derailleur during a ride. Once you have the upper and lower limit screws set correctly, there should be no need to make further adjustments, unless you move the derailleur from it's attachment on the seat tube. You might need to adjust the cable tension, which is done by turning the barrel nuts, but the correct limit setings are independant of the tension on the cable.

The lower limit screw determines how far inward the derailleur will travel when there is no tension on the cable. The upper limit screw determines how far outward the derailleur will travel when there is maximum tension on the cable. These should both be set by directly pulling and releasing the cable when the cable tension is slack. Once set properly, the limit screws should not have to be adjusted.

Adjusting the cable tension will determine how far derailleur will travel with each click of the shifter, but no matter how tight or loose the cable is, the derailleur will never travel past the limits that were set with the limit screws. Cables do wear and stretch, so it is necessary to readjust the tension occassionally to maintain smooth shifting.

 

[62vette]

Here is a good do-it-yourself guide to getting your front derailleur set up correctly - http://www.parktool.com/repair/readhowto.asp?id=75