chain dropping WITHOUT shifting?

[cleanwheels]

Please help me comrades. My gearing is 53/39 and 11-23.

During my recent rides, the chain has been dropping off the 39 when I stand on the pedals, always during the worst possible moment on steep grades.

I adjusted the inside limit of the FD, and thought things were better. Last few rides, no chain drop.

Today, the chain popped of the 39 every time I stood on the pedals under a heavy load, which is normally on a steep hill, using my 23 in the back.

Finally, on a very steep hill, the chain popped off the 23 in the back, and became wedged between the cassette and the wheel. ouch.

Please note, this is NOT during shifting.

WTH am I doing wrong? Please advise, thanks!

[eddief]

could be time for a replacement.

[FlashUNC]

B-screw adjusted for chain wrap? Front chainring worn?

[Lewis Moon]

Misalignment? Cracked chainstay? everything mentioned above?

[oldpotatoe]

Please help me comrades. My gearing is 53/39 and 11-23.

During my recent rides, the chain has been dropping off the 39 when I stand on the pedals, always during the worst possible moment on steep grades.

I adjusted the inside limit of the FD, and thought things were better. Last few rides, no chain drop.

Today, the chain popped of the 39 every time I stood on the pedals under a heavy load, which is normally on a steep hill, using my 23 in the back.

Finally, on a very steep hill, the chain popped off the 23 in the back, and became wedged between the cassette and the wheel. ouch.

Please note, this is NOT during shifting.

WTH am I doing wrong? Please advise, thanks!

I'd say the small ring is worn out and off the 23 is limit screw, imho

[zmudshark]

Check your frame closely, especially at the BB.

[CiclistiCliff]

Bent chainring? Loose bolts?

[Charles M]

B-screw adjusted for chain wrap? Front chainring worn?

and or, the entire drivetrain is worn... Including the chain and the cassette.


I used to be able to do this on super overly-flexible Litespeed Ghisallo. I can change gears on another Ti bike I have... even with newer drive materials.

checking the frame integrity is needed too.

[cleanwheels]

Check your frame closely, especially at the BB.


Thanks guys.

What am I looking for in particular when inspecting the frame?

[cleanwheels]

B-screw adjusted for chain wrap?

sorry for my ignorance--what does this mean? What is the b-screw?


Front chainring worn?

definite possibilty--2003 campy centaur


thanks!

[cleanwheels]

could be time for a replacement.

the chain,

or

the whole bike?:D:D

[cleanwheels]

I'd say the small ring is worn out and off the 23 is limit screw, imho

thanks, I will check it out

[oldpotatoe]

thanks, I will check it out

The 'b' limit is the screw that either tightens a spring in the top pivot or lower pivot(Campagnolo) that rotates the top pulley away from the cogset. Not your problem tho.

[cleanwheels]

and or, the entire drivetrain is worn... Including the chain and the cassette.

Definite possibility. 2003 campy centaur throughout; only new stuff is a recent right shifter rebuild and new cables.




checking the frame integrity is needed too.

any particulars to be on the lookout for?

thanks guys

[lhuerta]

OP: no offense, but based on your responses it sounds like u need some professional help. We can all provide a fairly close diagnosis, but lots more info is needed as well as pics. In addition to the suggestions above, you need to check your rear der hanger alignment, limit screws on your rear der as well, chain length and wear, chainring tooth alignment and wear, etc, etc, etc....

[cmbicycles]

2003 drivetrain w/ nothing ever replaced? If yes to both and if there are a decent amount of miles, then its worn out. In that case, new Cassette & chain at minimum, possibly chainrings as well. How is your favorite LBS?

Sent from my LGL41C using Tapatalk

[cleanwheels]

2003 drivetrain w/ nothing ever replaced? If yes to both and if there are a decent amount of miles, then its worn out. In that case, new Cassette & chain at minimum, possibly chainrings as well.

Bought new in 2003--rode about 8k miles on it that year, then took a decade off.

Started up again this year, 2k miles. So drivetrain is around 10k miles in at this point. I know there are many variables, but what is a rough mileage expectancy for these drivetrain components?

LBS is good, they're helping me put chorus on my new bike. Looks like I might need to invest in new drivetrain for my current bike too.

thanks amigos

[Kirk Pacenti]

I've had this happen once. Turns out it was a cracked frame. (Merlin Cielo)

Cheers,
KP

[cleanwheels]

I've had this happen once. Turns out it was a cracked frame. (Merlin Cielo)

Cheers,
KP

sorry to be a dumbass newb, guys, but the repeated warnings about the frame as possible cause: is the thought that the cracked frame or bottom bracket is allowing so much flex that it's popping off the chain when under load?

thanks!

[CampyorBust]

There is some play somewhere. I would make sure the BB, cranks, cassette, chain ring bolts and rear wheel are not loose. Then check to see how worn you drivetrain is.

[dave thompson]

sorry to be a dumbass newb, guys, but the repeated warnings about the frame as possible cause: is the thought that the cracked frame or bottom bracket is allowing so much flex that it's popping off the chain when under load?

thanks!

Yes. If the frame is cracked somewhere, the flex that the crack allows could cause significant problems with shifting including chain fall. If your bike were mine, I would strip the frame of its drivetrain and carefully inspect the whole area around where the bottom bracket/down tube/seat tube/chain stays come together along with the intersection of the chain stays, seat stays and dropouts.

[cmbicycles]

Chains will get 1.5-4k miles depending on a variety of maintenance and conditions factors. After that the worn chain accelerates wear on the cassette and chainrings. With 10k miles, i don't think your drivetrain owes you anything. Sounds like thats the probable cause of your issue, probably not a broken frame. Still, its worthwhile cleaning the frame well and checking all the tubes/welds/etc while the drivetrain is being replaced.

Sent from my LGL41C using Tapatalk

[CMiller]

With the responses suggesting it could be a cracked frame, I would take it to a reputable local shop to have a look. I wouldn't trust most of the shops in my area on a bike I really loved, best to find someone who has been wrenching for a while. I'm certain some forum members could give you local suggestions.

With the miles given, it deserves a new chain and cassette, but while the chain is off, why not clean it up and take a close look to be safe?

Good luck!

[cleanwheels]

Thanks for all the advice, fellas. Checked the frame everywhere, all seems intact. However, chain is old and a little stretched, and many of the 39-ring teeth were very worn down. LBS agrees.
New chainrings, chain, and cassette on the way.
Gracias!

[oldpotatoe]

Thanks for all the advice, fellas. Checked the frame everywhere, all seems intact. However, chain is old and a little stretched, and many of the 39-ring teeth were very worn down. LBS agrees.
New chainrings, chain, and cassette on the way.
Gracias!

Bike shop no have?