FD won't shift to largest chainring - help!
 

Hi everyone.

This morning I rode to work and on my way back found that I couldn't shift to the largest chainring. I have a Shimano Ultegra triple FD, rings 52-42-30. I heard a sound that sounded like metal rubbing on metal.

I took a look and found that the FD couldn't get over the largest chainring, causing the outer chainring to rub against the front derailer. I don't know how this could have happened - I haven't had any accident to bump it out of place, and I just got this bike built up for me a couple of weeks ago, so the parts haven't had too much wear and tear from me.

I don't know how this happened (that the front derailer somehow is too low to shift to the largest chainring), or how to fix it. Can this be fixed simply? If I can take some pictures I will.

1) Loosen the clamp bolt for the FD and raise it up so that the cage sits about 1-3mm above the big ring.

2) Tighten that clamp back down; It sounds like it slipped when you shifted. No big deal :)

The person who put the bike together for you just didn't tighten it enough. If the frame was just waxed, that can really contribute to the problem. I've used a rubber "shim" made from a piece of innertube as a ghetto fix before.

All right. I finally got it to shift to the big ring, but it makes a lot of noise when it's there; granted this is just from adjusting on a stand, I don't know if that will fix itself when I ride.

Ummm ... did you try Kevin's suggestion ??

Homebrew, what are you referring to with your signature?

Yes, I did exactly what he said to do. The big ring still makes more noise (it makes noise, period) than the other two. The FD now shifts sort of reluctantly to the outer ring, it seems like I have to really push the shifter into position to get it to go there, and it doesn't shift there very quickly.

Hmm ok. Is the cage parallel with the ring? When you look down on the FD cage, it should be in the same "line" as the big ring; not twisted or what not.

If it was shifting correctly before this morning, it has to be something simple. I doubt your limit screw would turn itself.

Please post a picture with the FD in the position that's causing the problem...It's hard to diagnose over teh internets.

Okay, I'll see what I can do.

Hopefully this helps, sort of, maybe. I only have a camera on my cell phone at the moment.
http://img255.imageshack.us/img255/8459/fd1lw7.th.jpg

Geez, that's a nice clear picture! But from what I can make out, the cage looks to be rubbing at the rear inside. Is that correct? If so adjust the dérailleur clamp so that it is more parallel to the rings, and about a penny's thickness above the large ring. These aren't biopace rings, are they?

Maybe start from scratch?

http://www.parktool.com/repair/byregion.asp?catid=53

Looking from the top down, the derailleur needs to be rotated clockwise very slightly.

I concur (obscure Seinfeld reference)

No, they aren't Biopace.

also the factory manual is available for download here:

http://techdocs.shimano.com/media/te...9830616213.pdf

between the two of those you should have all the information you need

Aha! It has been solved. Thanks to the people at the campus bike shop, it all works now. Turns out that although the outer side of the FD cage looked perfect (about 1 mm above the big ring), the inner side of the cage was rubbing against the middle chainring. The FD was raised about 2 mm and it ran perfectly after that.

As it turns out, I just looked at the specs on the factory manual and lo and behold, the minimum difference between outer and middle chainrings is 13t. D'oh! I'm running 52-42-30, a difference of 10t. Oh well. It now looks too high, but isn't. It's only a couple millimeters anyway.

Thanks for all the help, though!

Glad you got it figured out. Few things are as annoying as a FD that doesn't shift properly.