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Busted chained mangled my derailleur!

Old 01-22-21, 06:13 PM
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twowheelies
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Busted chained mangled my derailleur!

So can/should I replace my shimano dura ace RD 6600 9-speed with something else? Or stick with the original and find the best one I can on Ebay?

(I dont think mine can be realigned - bent way out of shape.)

Thanks all.
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Old 01-22-21, 06:28 PM
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Originally Posted by twowheelies View Post
So can/should I replace my shimano dura ace RD 6600 9-speed with something else? Or stick with the original and find the best one I can on Ebay?

(I dont think mine can be realigned - bent way out of shape.)

Thanks all.
9 speed Dura Ace is 7700. 6600 is 10 speed Ultegra. No matter, you can use any Shimano 9 speed or 10 speed (road) with the exception of current Tiagra/4700. 7800 Dura Ace is the pick of the litter if you can find a nice one. Replace your chain as well.
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Old 01-22-21, 07:27 PM
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Thanks - yes I meant 7700...! so the 7800 will work with the 7700 shifters?
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Old 01-22-21, 07:29 PM
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yes
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Old 01-22-21, 07:30 PM
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Originally Posted by shelbyfv View Post
9 speed Dura Ace is 7700. 6600 is 10 speed Ultegra. No matter, you can use any Shimano 9 speed or 10 speed (road) with the exception of current Tiagra/4700. 7800 Dura Ace is the pick of the litter if you can find a nice one. Replace your chain as well.

And yeah, good call on replacing the chain...! 😆

seriously tho, should I stick with shimano on the chain? Or is there something more durable? There is this one short but very steep climb under the george washington bridge I ride quite often, which is where I broke it today...
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Old 01-22-21, 07:39 PM
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IMO, 9 speed chains from Shimano, SRAM or KMC should be equally durable. It's pretty unusual for a chain to break while just riding along, even with a big load. Usually the chain has been previously compromised by chainsuck or some other mishap. Also chains can break if improperly connected. For your 9 speed and higher they should only be connected with a quick link or Shimano pin. Don't try the old method of pushing an existing pin back in.
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Old 01-22-21, 07:50 PM
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Chains rarely brake from pure tension. Just about every (of the hundreds of busted chains I've seen) "failure" is due to some preexisting issue. maybe only preexisting for a few pedal strokes but not because the chain spontaneously came apart. Perhaps the most common reason is a shift some time before that wasn't done well and the too high twisting forces (that is why modern chains have peened over ends of the pins) managed to wedge a side plate partially or fully off the pin end. Then with only one end of the pin holding things together it only takes a high effort to bend the remaining side plate over and let the male end of the chain slip off the pin. Sometimes if the chain was installed with a connecting pin and if both ends of that pin weren't properly seated in the side plates the same prying off can happen. I have seen bent over teeth (again usually from jam shifting) damage chains but this is usually preceded by a lot of chain meshing complaints that are hard to ignore.

If you replace the chain check the cog teeth wear, a worn out cog will cause a new chain skip when under power.

You do shift with no pedal pressure all the time, don't you Andy
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Old 01-22-21, 08:06 PM
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Originally Posted by Andrew R Stewart View Post
Chains rarely brake from pure tension. Just about every (of the hundreds of busted chains I've seen) "failure" is due to some preexisting issue. maybe only preexisting for a few pedal strokes but not because the chain spontaneously came apart. Perhaps the most common reason is a shift some time before that wasn't done well and the too high twisting forces (that is why modern chains have peened over ends of the pins) managed to wedge a side plate partially or fully off the pin end. Then with only one end of the pin holding things together it only takes a high effort to bend the remaining side plate over and let the male end of the chain slip off the pin. Sometimes if the chain was installed with a connecting pin and if both ends of that pin weren't properly seated in the side plates the same prying off can happen. I have seen bent over teeth (again usually from jam shifting) damage chains but this is usually preceded by a lot of chain meshing complaints that are hard to ignore.

If you replace the chain check the cog teeth wear, a worn out cog will cause a new chain skip when under power.

You do shift with no pedal pressure all the time, don't you Andy

actually i was already all the way down in 1st and almost to the top of the hill when the chain came off. I didn't realize it was broken until later then it caught in the derailleur!
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Old 01-22-21, 08:10 PM
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Originally Posted by shelbyfv View Post
IMO, 9 speed chains from Shimano, SRAM or KMC should be equally durable. It's pretty unusual for a chain to break while just riding along, even with a big load. Usually the chain has been previously compromised by chainsuck or some other mishap. Also chains can break if improperly connected. For your 9 speed and higher they should only be connected with a quick link or Shimano pin. Don't try the old method of pushing an existing pin back in.

its s new chain, but since it didn't with a connector pin (the kind you break part off of once installed) or quick link, i did pull a pin halfway out, then push it back in. could that hav been the cause...!?
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Old 01-22-21, 08:15 PM
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Bingo!!! Modern chains with peened pin ends will punch the side plate hole larger when the pin is, un purpose or not, removed. Then if that same pin is pushed back in the larger hole won't grip the side plate as well as it should. This reason is likely in the top 5 of chain breaking reasons. Andy
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Old 01-22-21, 08:20 PM
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Originally Posted by Andrew R Stewart View Post
Bingo!!! Modern chains with peened pin ends will punch the side plate hole larger when the pin is, un purpose or not, removed. Then if that same pin is pushed back in the larger hole won't grip the side plate as well as it should. This reason is likely in the top 5 of chain breaking reasons. Andy

ah ok - a slightly expensive lesson! but thank you for the info, much appreciated.

so if the next chain doesn't come with a pin or quick link, do i need to get that separately?
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Old 01-22-21, 08:25 PM
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Go back to the shop where you bought it from and explain the situation and that you want to check that the replacement chain you buy from them has the pin or link in the package. Shimano often has the pin in a separate plastic "sleeve" and can get lost in the instructions. Others times the extra bits can become lost in the handling of the chain's box.

When I sell a chain I sometimes ask if the buyer has installed a bike chain before and will offer advise if the reply I get seems a bit "vague". Andy
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Old 01-22-21, 08:34 PM
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Ok good call - i bought the;last one on amazon. Next time i'll go to my lbs.

hey thanks for all the help!

Joe
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Old 01-22-21, 09:28 PM
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Originally Posted by twowheelies View Post
its s new chain, but since it didn't with a connector pin (the kind you break part off of once installed) or quick link, i did pull a pin halfway out, then push it back in. could that hav been the cause...!?
It was on my last broken chain.
I was going on vacation and needed to swap in a "mountain" cassette. Without thinking, I spliced in a few links to lengthen the chain.
It worked fine for me, but when I loaned the bike to a friend (a much stronger rider) while I worked on his, he parted the chain and turned the RDER into a pretzel.
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Old 01-22-21, 10:12 PM
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Originally Posted by Andrew R Stewart View Post
Chains rarely brake from pure tension. ...
Really Andy, you know better! Chains only brake on fix gears! (And only gently on mine since I use brakes.)

Outside that, great post.

Ben
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Old 01-22-21, 11:47 PM
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Originally Posted by 79pmooney View Post
Really Andy, you know better! Chains only brake on fix gears! (And only gently on mine since I use brakes.)

Outside that, great post.

Ben

Ben- You got me. Thanks, Andy
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Old 01-23-21, 10:12 PM
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Originally Posted by twowheelies View Post
ah ok - a slightly expensive lesson! but thank you for the info, much appreciated.

so if the next chain doesn't come with a pin or quick link, do i need to get that separately?
I use SRAM and KMC chains and they come with the masterlink or quick link. I have a preference for SRAM if 9 spd and below, and KMC if 10 spd and above. Both brands are solid, and I prefer over a replacement pin that Shimano uses.

Too bad about the expensive lesson. Fortunately, you didn't get hurt when the chain let loose..

As we say, "experience is the teacher that gives the final exam first".
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