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Front Derailleur Installation(17 posts)

Front Derailleur InstallationSamDC
Dec 10, 2002 7:58 AM
So last night I attempted to install the last major component on my new bike: the infamous front derailleur (I discovered why it's infamous).

I didn't think it would be too hard. Clamp it onto the seat tube, make sure the outer plate is parallel to the big chain ring and 1-2 mm above it. Pretty much just followed the instructions that came with it (it's an Ultegra double with Dura Ace shifters).

Man, I tried everything I could think of after following the instructions didn't work. For example...

Tried to take out as much slack as I could humanly possible. Wouldn't shift to the bigger chain ring because there was too much tension.

Left a little extra slack so that it would shift upshift. Result was too much chain rub on the outer plate.

Tried getting the inner cage setup first and then tensioning up the cable at the barrel adjuster. Kind of worked but still a lot of chain rub on the outer plate.

Is there something fundamental that I'm missing? I don't want to damage the shifters or derailleur, so I may have to resort to letting the mechanics at the LBS resolve this.

Thank you, thank you, thank you for any help.
Try thisBipedZed
Dec 10, 2002 8:10 AM
Assuming the derailleur is positioned correctly which it sounds like it is then

1. Adjust low gear limit (inner cage) with the cable UNATTACHED. This is most likely your problem. If you do this adjustment with the cable attached the cable itself will determine the throw, not the derailleur. Chain should be on small chainring and largest cog.

2. Attach the cable pulling it taut by hand. Don't use pliers to pull the cable as you are attaching as it will pull it too tight and effect range.

3. Shift to small cog and large ring and adjust high gear limit (outer plate).

Hope this helps.
Tried thatSamDC
Dec 10, 2002 8:21 AM
Thank you for your suggestion, Zed.

That's basically what the Shimano instructions had outlined. If I recall correctly, I had too much chain rub on the outer plate, leading me to believe that there was not enough tension in the cable to move the plate out more (is that correct?).

I corrected the tension with the barrel adjuster (a quater turn at a time until the rub was eliminated), but then it couldn't shift to the smaller ring because there was too much tension in the cable.

Oh well, keep on truckin'...
dumb questionlonefrontranger
Dec 10, 2002 8:41 AM
Did you try letting a tweak out of the upper limit screw? If your barrel adjuster won't make the throw, it means your limits are off.

Sorry if you already tried this.

You might check to see that the cage plate itself isn't slightly off (bent or wacked somehow). Front mech can be paralyzingly frustrating, 'cause it's such a darned simple device. Unfortunately it needs to be adjusted in 3 planes of movement (up/down, in/out and laterally/rotationally), so it's more complex than it first appears.

Good luck. Sometimes it's merely best to have a beer and a bit of a think before going back to a job like this.
ditto re: tweaking upper limit screw_rt_
Dec 10, 2002 10:04 AM
if the cable tension is correct to get the chain to shift but you are getting chain rub on the outer plate of the der. then it sounds like the issue is an outer limit screw adjustment.

if you don't have a copy of Zinn & the art of Road bike maintenance, pick one up at your local Barnes & Noble. he does a great step-by-step on setting up front der adjustment.

rt
Tried that tooSamDC
Dec 10, 2002 10:31 AM
Hi rt, thank you for your reply.

I've let the upper limit all the way out so that it's not contacting the cam in the derailleur at all. I think it's a cable tension issue. I also have the Zinn book, but (gasp)found the Shimano instructions somewhat more precise and continuous.
hmmm, well then..._rt_
Dec 10, 2002 12:01 PM
i guess i'm all out of suggestions! ;-)

good luck.

rt
re: Front Derailleur Installationmotta
Dec 10, 2002 8:10 AM
go to www.cyclingnews.com/tech and they have a bike repair and maintenance section. It has a really good description of adjusting the front mech. With pics!
Solution: Buy Campy. :)No_sprint
Dec 10, 2002 8:39 AM
Sorry, couldn't resist!
..beat me to it, and micro-adjust the FD from the shifter. nmSpunout
Dec 10, 2002 9:22 AM
re: Front Derailleur Installationrdbkr
Dec 10, 2002 8:40 AM
Only thing I can think of is that perhaps it could be a compatibility issue between the Dura-Ace shifters and the Ultegra FD. Shimano has been known to pull stuff like that. Someone out there should know for sure.
definitely notweiwentg
Dec 10, 2002 8:56 AM
I used that setup. no issues at all.
re: The front shifter has trim positions......Rusty Coggs
Dec 10, 2002 10:09 AM
Noone seems to have mentioned this angle.Shimano instructions for derailer installation are as good as they get if followed.Never a problem with lots of different combinations.Having shifer instructions helps.
Tried to try this... :)SamDC
Dec 10, 2002 10:40 AM
Thank you for your reply, Rusty.

I tried to trim the front derailleur to eliminate the rub, but it seems that when I tension the cable the trim settings seem to disappear. Weird huh? I think I might be pushing to hard on the levers, thus by-passing the index positions. Gonna try this again tonight.

Another thing I remember is that sometimes when I push on the lever, I am able to shift the chain from the smaller to larger ring. The derailleur will move out, but the shifter doesn't seem to want to 'catch' and thus drops back down to the smaller ring. Is this a cable tension issue or something else? Anwyay thanks for you help.
re: Front Derailleur InstallationTheKid
Dec 10, 2002 11:01 AM
I bought a used bike and had the same problem. After playing with the cable tension and limit screws, I took it to a friend who is an amateur mechanic. He tweaked/bent the derailleur to make it wider. It worked fine after that. He said the mechanic at the LBS did the same thing to his bike. There was a discussion about the same thing about nine months ago on this same subject and I do not remember anyone being able to solve the problem.

It does not make sense that there is not enough movement in the shifter to avoid this, but I was not able to fix it any other way.
re: Front Derailleur Installationfunknuggets
Dec 10, 2002 2:56 PM
I think your cable is too stretchy.
re: Front Derailleur InstallationNug
Dec 10, 2002 8:25 PM
Park tools website has a whole section on this, helped me alot. Sometimes a different description of the same job helps, hopefully?