Help! RD doesn't take up chain slack!

[Bob Ross]

This problem just started appearing with my 7-year-old Ultegra 6700 rear derailler:

The entire RD assembly no longer swings all the way rearward to take up the chain slack when I shift towards smaller cogs.

It seems to be most prevalent when I'm in the small chainring, to the point where I can't use the 5 smallest cogs or the chain goes too slack to shift and often too slack to engage the drivetrain & propel the bike forward reliably.

It's less of an issue when I'm in the big chainring, but still causes skipping and misshifting in those smaller cogs.

Thinking the problem might be dirt/gunk impeding the return spring -- I'm just presuming there is a "return spring" that controls this aspect of an RD's function, hell if I know -- I removed the RD from the bike and gave it a good soaking/cleaning with Simple Green, followed by a liberal dousing with WD-40. That seemed to cure the misbehavior for one or two rides, but now it's happening again.

So...what's going on, and what's the cure?

Looking at an exploded parts view here (http://si.shimano.com/pdfs/ev/EV-RD-6700-A-3309A.pdf) I gather that coily spring that's part of the "B-Axle Assembly" could be the culprit? Is that something my LBS can easily replace? Is that something I can buy at my LBS and replace myself? Is there some other part or sub-assembly that's more likely the culprit? Or is my entire RD shot, in need of replacement?

Thanks.

[Cicli]

Just get a new derailuer. Its fixable but may not be worth it.
10 speed stuff is affordable.

[bikinchris]

Yes, a good mechanic can repair a rear deraillier with a loose B spring and can even turn that tension higher. But the spring #6 on your diagram does most of the work of pulling the chain tension. That spring can also be turned tighter.
Are you sure your chain isn't just too long?

[Ken Robb]

BTW, WD-40 isn't a very good LUBRICANT. That's not its intended use.

[Bob Ross]

BTW, WD-40 isn't a very good LUBRICANT. That's not its intended use.



Yes, I was using it as a water displacer after the soak in Simple Green.

[pbarry]

Maybe disassemble the pivot and spring assembly. Degrease, dry, relube and reassemble. See if that helps. Yes, you can replace the spring yourself. The LBS may even have a new spring or a donor RD they can rob.

[peanutgallery]

Don't be cheap - buy a new one, current one owes you nothing after 7 years. That's a good life

[asiantrick]

I would advice you to buy a new one. Not worth fixing something that's over 7 years old.

[JWDR]

Not worth fixing something that's over 7 years old.

I would say this is the worst advice I've seen on Paceline.

[oldpotatoe]

This problem just started appearing with my 7-year-old Ultegra 6700 rear derailler:

The entire RD assembly no longer swings all the way rearward to take up the chain slack when I shift towards smaller cogs.

It seems to be most prevalent when I'm in the small chainring, to the point where I can't use the 5 smallest cogs or the chain goes too slack to shift and often too slack to engage the drivetrain & propel the bike forward reliably.

It's less of an issue when I'm in the big chainring, but still causes skipping and misshifting in those smaller cogs.

Thinking the problem might be dirt/gunk impeding the return spring -- I'm just presuming there is a "return spring" that controls this aspect of an RD's function, hell if I know -- I removed the RD from the bike and gave it a good soaking/cleaning with Simple Green, followed by a liberal dousing with WD-40. That seemed to cure the misbehavior for one or two rides, but now it's happening again.

So...what's going on, and what's the cure?

Looking at an exploded parts view here (http://si.shimano.com/pdfs/ev/EV-RD-6700-A-3309A.pdf) I gather that coily spring that's part of the "B-Axle Assembly" could be the culprit? Is that something my LBS can easily replace? Is that something I can buy at my LBS and replace myself? Is there some other part or sub-assembly that's more likely the culprit? Or is my entire RD shot, in need of replacement?

Thanks.

If it's just gunk, take it apart, clean, lube..maybe move the end of the spring to a 'tighter' hole. The suggestions to just replace the thing..geeez, what's happened to good old wrenching on stuff like this...:eek: Take it apart, clean, lube...not hard.

[weisan]

If it's just gunk, take it apart, clean, lube..maybe move the end of the spring to a 'tighter' hole. The suggestions to just replace the thing..geeez, what's happened to good old wrenching on stuff like this...:eek:

throw-away culture.

[Pierre]

This is likely your issue.

https://www.youtube.com/watch?v=bgiNuJNynMc

Love this guy - very pragmatic solutions for bike part fixes.

[charliedid]

This is likely your issue.

https://www.youtube.com/watch?v=bgiNuJNynMc

Love this guy - very pragmatic solutions for bike part fixes.

He sure loves solvent but seems allergic to grease. Might have been his problem all along since his last overhaul :-)

[Fatty]

Don't be cheap - buy a new one, current one owes you nothing after 7 years. That's a good life

7 years old is just getting broken in. Give another blast with the WD and blow that out with compressed air if you have access to it , then a good shot of oil should free it up.

[FlashUNC]

throw-away culture.

I have a hard time blaming the advice when Shimano makes it impossible to rebuild and service, for example, their shifters.

And yeah, if the RD has had seven years of hard living and is clapped out, might be time for a new one.

[Look585]

This problem just started appearing with my 7-year-old Ultegra 6700 rear derailler:

The entire RD assembly no longer swings all the way rearward to take up the chain slack when I shift towards smaller cogs.

<snip>

I have a 6700 RD I'll send you, gratis. A very nice forum-pal sent it to me for free (thanks Augi) to harvest the long cage to graft onto a 6770 Di2 for more chain wrap. I bolted the short Di2 cage back to the analogue mech and am happy to pass it on.

FYI, the disassembly, clean, lube, reassembly of the B-axle is a 15 minute job requiring nothing beyond basic tools (3mm, 5mm, Philips).

[peanutgallery]

Have at that 6700 rear mech spring. Stand by the advice to just repalace

http://www.pezcyclingnews.com/features/equipment-nostalgia-fact-or-fiction/#.WUf-NWgrK00

[hokoman]

I have a 6700 RD I'll send you, gratis. A very nice forum-pal sent it to me for free (thanks Augi) to harvest the long cage to graft onto a 6770 Di2 for more chain wrap. I bolted the short Di2 cage back to the analogue mech and am happy to pass it on.

FYI, the disassembly, clean, lube, reassembly of the B-axle is a 15 minute job requiring nothing beyond basic tools (3mm, 5mm, Philips).

I had no idea what you were going to do with it... very cool!

[Bob Ross]

I have a 6700 RD I'll send you, gratis. A very nice forum-pal sent it to me for free (thanks Augi) to harvest the long cage to graft onto a 6770 Di2 for more chain wrap. I bolted the short Di2 cage back to the analogue mech and am happy to pass it on.

Whoa, thanks! PM sent

[pbarry]

Have at that 6700 rear mech spring. Stand by the advice to just repalace

http://www.pezcyclingnews.com/features/equipment-nostalgia-fact-or-fiction/#.WUf-NWgrK00

That's a good read. Maybe a little over the top, but in the realm of reality. Equipment choices were very few back then, but we made do. It definitely required more commitment to ride.