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Do I have Chain Suck? Threw the chain twice today,(8 posts)

Do I have Chain Suck? Threw the chain twice today,Spunout
Oct 12, 2002 12:21 PM
On my Campy Chorus 10 running 53/39 X 13/29. I threw the chain twice, once shifting up, and once shifting down. Both times, the chain ended up around the BB. I can put it back on by hand, in the pack at 60km/h on the descent ;-)

I don't want to do this all of the time, I think my adjustmets are all OK, nothing is over-throwing the chainwheel. The shifts were while coasting/turning the cranks, bumpy road was shaking things all over.

Is there a quick fix? Or, should I install one of those anti chain-suck mechanisms? You know, the black plastic ramp that mounts under your Front mech, and keeps the chain off the the BB. I don't even know what that thing is called, so can't Google it.

Help, comments, insults are always appreciated. I wasn't jumping any monuments as my chain fell off, honest.

re: Do I have Chain Suck? Threw the chain twice today,Juanmoretime
Oct 12, 2002 12:41 PM
No the problem is not chain suck. It sounds like the limit screws on your front derailluer are not adjusted correctly. Chain suck is when the chain sticks to teeth on the small chain ring and rides up the ring and the cahin jams between the ring and the stay chewing up your chain stay. One other area to check if you have to long a chain, riding on rough roads could cause it to jump off the ring. I would check the front derailuer first. on the small ring big cog on the back. Adujust the limit screw until the chain starts rubbing the chain, then back it off until it stops. That should fix your problem.
Do you have Chain Suck? No.Markus_B
Oct 12, 2002 12:51 PM
If the chain is pulled between chainstay and the little chain ring - that's called a chain suck. Never heard of a chainsuck in conjunction with a double road crankset.

I have that chain guides you described on all of my bikes (seems that I like them). One of these will prevent your chain being thrown on the BB housing.

To prevent the chain being thrown to the ouside, I would propose checking the der. adjustments once more (not only the screws but also the way the clamp is mounted).
Another possibilty..........gogene
Oct 12, 2002 1:59 PM that you are running in the small ring and small cogs. In that condition the chain can be pretty slack and/or if your chain is too long the chain can be bounce off the rings under bumpy conditions.
Thanks, what is the name of that do-hingy?Spunout
Oct 12, 2002 3:03 PM
Thinking about this, my limit screws are fine, I know how to set this up. My derailleur doesn't throw it off.

The Campy 10 rear cluster is WIIIIDE, and when I do front shifts around the top of the rear cogs (7-9), the chain line would 'suggest' that the chain will naturally move inside the small ring. Very fine system. Add a few bumps, and it is gone.
third eye chain watcher...C-40
Oct 13, 2002 4:48 AM
There are several brands of devices that will keep the chain off the BB. Excell Sports just started selling a new model that doesn't use a hose clamp like the third eye model. Check out their catalog.

I assume that you are using a campy BB to assure a proper chain line, and also have not set the chain too long or too short. I've been riding the campy 10 system for 3 seasons and never dropped a chain. It's not something that is common to 10 speed drivetrains.

Here's the proper way to adjust chain length:

Two simple tests will determine if the chain is the correct length. First, it must not hang loose in the little ring, little cog combination. Wrap the chain around the small chainring and through the derailleur in the normal manner. When the ends of the chain are brought together, some movement of the lower derailleur pulley should occur, indicating tension is being applied. Two more links (another inch) may need to be removed, beyond the point of absolute minimum tension, to keep the chain from rubbing on itself as it passes under the upper derailleur pulley. Once this is done, the chain is set to the maximum useable length. Removing additional links will do nothing but reduce the derailleur's capacity. It won't help keep the chain from skipping or jumping.

Second, the chain must be long enough to avoid overextending the rear derailleur when shifted to the big ring and biggest cog combination. If the chain is set to the maximum length as described, it should always pass this test, unless your setup exceeds the derailleur's stated capacity.

If you want to see how much lower pulley movement will occur, without removing the extra two links, shift up four teeth (11 to 15 or 12 to 16). This has the same effect as removing two links.
Oct 14, 2002 2:09 PM
Chain suck is when the chain doesn't come off the chainring and gets pulled up and into the chain stay and jams. Throwing the chain is something else entirely. It's due to worn components (not likely in your case), and bad chainline (again, not likely) or poor adjustment and setup. We're talking fine tuning of the limit screws on the order of 1/8th of a turn - no foolin'. You first need to check for *any* source of play in your drive train or shifting (i.e. a worn pivot in your front der.). If all of this sounds like too much tweaker-work then find a good tweaker and bribe them with good beer for best results.

BTW - that thing is called Chain Watcher or something like that and it's a ladies aide.
Thanks, will tweak. Funny that I've thrown both shiftingSpunout
Oct 15, 2002 4:09 AM
up and shifting down. I know, I should watch my rear cog position first (not in 8 or 9 position).

Looking at October's Cycle Sport Magazine, they offer a close-up of Lampre's Fondriest bikes. If that isn't a third eye I see there, maybe it is an on-board EPO delivery system ;-)

Lampre runs Record 10, maybe they have an issue here too.