experienced mechanic w/ problem

[Nolllies]

Ok, just throwing this one out there to see if anybody has a solution that doesn't end in "return it, it's broken." I just bought a Dura-Ace 10 speed rear derailleur for use with my ultegra ten speed setup. I have just finished installing the rear derailleur, and no matter how I adjust the limits and the barrels, I can't get the thing to shift into the smallest cog.
This is the 10 speed version of a dura-ace rear derailleur, I have had the limit screw for the high gear all of the way out without any luck shifting into the small cog. In addition, I do transport my bike in the back of my car frequently and, just to be sure, I checked the derailleur hanger earlier today; it was straight. When I place my ultegra rear derailleur back on, it works just fine. Anybody have an idea of what might be wrong with my derailleur?

 

[flapsupcleanup]

If it wont go into the smallest cog, the derailleur is not moving far enough to the right. Simple. Try removing the cable from the d/r to make sure cable tension isnt holding it from the stop. Or try pushing the d/r by hand to make sure it isnt hanging up internally.

 

[gclark8]

Set the "High" limit screw with the shift cable dis-connected.

 

[Nolllies]

If it wont go into the smallest cog, the derailleur is not moving far enough to the right. Simple. Try removing the cable from the d/r to make sure cable tension isnt holding it from the stop. Or try pushing the d/r by hand to make sure it isnt hanging up internally.

I tried setting the high limit screw without the cable connected and when I get halfway in between my highest gear and my 2nd highest gear, the derailleur stops on it's own. If the derailleur is hanging up internally, what tools do I need in order to open it up and find the problem?

 

[kdelong]

You can't open up that section of the derailer without ruining it. It is held together with four blind pins that are epoxyed in the blind end and peened on the open end. The best that you could hope to do is to drill out the pins, but they are stainless steel.

I serously doubt that the derailer is hanging up internally. I'll bet that this is actually a 9-speed derailer that you've got. That's what it sounds like.

 

[Nolllies]

I serously doubt that the derailer is hanging up internally. I'll bet that this is actually a 9-speed derailer that you've got. That's what it sounds like.

it is a 7800. I am certain that it is a 10 speed. It is easy to tell the 9 and 10 speed apart, the pullies on the 10 speeds are solid discs, while the 9 speed has the spoked pullies. The "Dura-Ace" logo on the 9 speed is also significantly larger.

 

[Nolllies]

Do any of you have a simple way of distinguishing a derailleur with disfunctional internals? Is there anything else that I should try before conceeding that this derailleur will not work?

 

[LeDomestique]

Return it....it's broken !

;-)

 

[pistole]

what sort of cogset do you have ? And what sort of hub is it attached to ?
.

 

[bobbyOCR]

double check your spacers on your cassette and also re-mount the derailleur to the frame. run it with chain and no cable attachment and if the problem persists, send pictures to us to show us the problem, or warranty it. Better yet, take out the high limit screw (or both, just in case you accidentally mistook the screws) temporarily and double check. Then take it to a more experienced mechanic. Out of all the road bikes that have gone through me, most have been cassette spacing and improper limit screw adjustment, in mtb, maybe a bent hanger, but never this.

 

[Mampara]

Never mind, you already mentioned what I wanted to say.

 

[kdelong]

After all this, just take it to your LBS and let them worry about it. You'll probably have to pay for it but they'll have the bike in their hands and should have better resources than most of us on this forum.

 

[alfeng]

I have just finished installing the rear derailleur, and no matter how I adjust the limits and the barrels, I can't get the thing to shift into the smallest cog.

I have found that the fastest & easiest way to set the stops on a "new" (to the bike) rear derailleur is WITHOUT EITHER the chain OR cable attached to the rear derailleur ... but, of course, with the rear wheel & specific cassette(-type) in the frame.